Is P20+Ni Better Than P20 Mold Steel | When to Upgrade Your Material

P20 is only 28–32HRC, suitable for ≤ 300,000 times production.

When mold > 500mm thick or lifespan requirement doubles time should upgrade to P20+Ni.

What Does Nickel Actually Do

Hardenability

A piece long 1500 millimeters, wide 800 millimeters, thickness reaching 600 millimeters P20 steel material is lifted out by giant overhead crane, the whole piece steel material weighs up to 5.6 tons. Surface layer is burned to 850℃, presenting dazzling bright red color.

Overhead crane steel wire rope descends, red-hot huge steel block is rapidly immersed into 200 tons capacity quenching oil tank. Large amount oil liquid instantly violently boils, emitting rolling thick smoke. Steel block outermost layer's temperature in short 3 minutes suddenly drops to 200℃ up and down.

Up to 800℃ heat needs to penetrate 300 millimeters thick solid metal layer, then can little by little transfer to external cooling liquid in.

Passing 12 hours long cooling, worker brings hardness tester to conduct testing. Surface reading stays at 32HRC. Large band saw machine roaringly cuts this piece 5.6 tons steel material from right middle open. Again measure cross-section center, hardness tester's pointer only hits 22HRC.

Change on a piece size completely same 1.2738 steel material, formula inside extra added 0.9% to 1.1% nickel element.

Nickel element early already drilled into iron atoms' micro gaps inside. It quietly delayed carbon atoms' moving footsteps in cooling temperature-dropping stage.

· Cooling speed's requirement from per second 20℃ is relaxed to per second 4℃ within.

· Martensite starting to form's temperature is pulled down by about 15℃.

· Pearlite's appearance time is pushed back delayed for very long.

· Metal internal structure transformation's safe time window extra came out nearly 40 minutes.

Thick reaching 600 millimeters steel block internal cooling still needs ten several hours. Relaxed time window exactly caught this slow cooling beat.

Cut open this piece containing about 1% nickel 1.2738 steel material. Surface hardness is measured 31HRC. Holding hardness tester along cut open face walking inward, every interval 50 millimeters hitting a point.

Reading from 30.5HRC becomes 30HRC. Until deep into 300 millimeters most center position, hardness tester screen jumping out number is 29HRC.

South's an injection molding factory received this batch steel material made large car bumper mold. Workshop inside that injection molding machine is like a behemoth, clamping force up to 3500 tons.

Melted into paste shape polypropylene plastic is pushed forward by screw high speed. Up to 120MPa extremely high pressure puts plastic tightly pressed into mold cavity inside.

Surface hardness 32HRC ordinary P20 mold, below 300 millimeters deep place only has 22HRC soft bottom. Facing 3500 tons repeated squeezing, bottom fundamentally cannot hold.

After hitting finish 150,000 mold times, mold cavity most center's that piece area shriveled downward 0.15 millimeters. This 0.15 millimeters physical depression, makes molded out car bumper surface add a visible weld line, edges hung full of flash.

Stop production one day, 800 pieces car bumpers' production capacity then hit water splash.

Change on that set surface to core hardness only differed 2HRC 1.2738 mold. 3500 tons furious impact force smashes down, is firmly caught by whole piece 5.6 tons, inside outside same hard steel material.

· Two pieces molds closing place's gap tolerance is tightly bitten within 0.02 millimeters.

· Continuously hitting finish 300,000 mold times, cavity's dimension deviation amount did not exceed 0.03 millimeters.

· 120MPa injection pressure under packing stage is extremely stable.

· Every mold's injection cycle is firmly nailed dead at 45 seconds.

Thickness exceeding 800 millimeters even 1000 millimeters super large steel blocks, ordinary carbon manganese steel meeting water meeting oil cooling, hardness only can go down 50 to 80 millimeters. Again drilling into deep place, metal structure all turned into loose weak dough-like structure.

After adding nickel, steel material eating hard's depth flipped quite a few times. Under containing 1.05% nickel formula, material downward deep into 400 millimeters place, yield strength still tops at 850MPa above.

CNC milling machine operator Old Wang towards processing process's feeling is extremely deep. Processing ordinary thick steel plate, drill bit cutting to deep place time machine tool spindle received resistance obviously becomes small. Discharged out iron chips become one section section short broken pieces, edges all are torn pulled open burrs.

Operating machine tool processing this piece nickel-containing thick heavy material, using a handful diameter 50 millimeters U-drill downward hard hitting 400 millimeters deep water channel hole. Machine tool spindle load ammeter's pointer from head to tail absolutely still, stopping at 18 amperes position.

Cut down iron chips along drill bit chip flute surge out, rolling into one strip strip long spring shape. Iron chips' color presents uniform deep blue color.

· Deep hole drill downward piercing's feed speed is set at per minute 50 millimeters.

· Cutting area's temperature is suppressed by cooling liquid at 150℃ within.

· One furnace iron chips discharged finish, hard alloy blade on did not stick a little broken iron.

Processing deep reaching 350 millimeters complex cavity, CNC program running finish a large half, only stopped machine changed one time blade insert.

Forging workshop's 3000 tons hydraulic press is exactly facing containing 1% nickel large steel ingot back and forth hammering. Steel ingot internal fine micro holes under 1100℃ high temperature are thoroughly pressed solid by several thousand tons strength.

Pre-hardening heat treatment process inside, oil quenching cooling is extremely brutal. Large steel blocks are bearing several hundred degrees temperature difference brought huge pulling tearing force.

1000 millimeters thick nickel-containing huge steel ingot carried withstood this kind cold hot pulling tearing. Inspector holding ultrasonic flaw detector along surface drawing grids little by little sweeping past, did not sweep out any exceeding diameter 1.0 millimeters crack alarm sound.

Toughness

Die casting workshop inside 1200 tons injection molding machine every day opens closes several thousand times. Normal temperature cooling water inside mold water channel circulates at per minute 15 liters flow rate. Injection molding nozzle shooting out ABS plastic melt temperature is up to 240℃.

Mold interior has one place deep reaching 180 millimeters, thickness only 1.5 millimeters reinforcing rib bone position. Closing mold instant local part bears several hundred megapascals stress.

Using un-added nickel carbon manganese steel processing aforementioned mold, ledger record is extremely unoptimistic. Running finish 80,000 mold times, operator holding magnifying glass checks, reinforcing rib bottom 90 degree right angle intersection place appears 0.2 millimeters long micro crack.

Crack spreading speed is extremely fast. Hitting to 110,000 mold times, naked eye barely visible fine line extended to 15 millimeters. High pressure injection molding time plastic along gap drills into interior, ejector mechanism is completely stuck dead.

Whole production line pulls switch stops electricity. Hardness and anti-cracking ability in iron steel materials always are opposing attributes. Put steel material burned red quenched to become hard, anti-wear ability rises, metal itself becomes like glass equally brittle.

Testing room has a heavy-duty Charpy impact testing machine. Weighing up to 30 kilograms pendulum high high hangs up, aiming at a piece opened having V-shape notch ordinary P20 steel standard testing block ruthlessly smashes down.

Testing block instantly breaks into two sections, fracture presents rough crystalline particles. Dial pointer stays at 18 joules position, number represents material absorbing impact energy's limit value.

Melting furnace inside added 1% or so nickel element, changed metal grains' growth way. Under 500 times microscope observing, originally coarse large grains are cut divided into dense fine sand-like structure.

Added nickel 1.2738 standard block is put into testing machine pedestal. 30 kilograms pendulum carrying extremely large potential energy smashes hitting notch. Accompanying dull metal tearing sound, testing block breaks open.

Fracture edge appears visible metal stretching deformation trace. Dial pointer sweeps past scale, ultimately stopped at 32 joules. Increasing 1% nickel content, steel material resisting impact cracking ability improved nearly 80%.

Value change feeds back to mold processing ledger, behaving as extremely concrete processing performance:

· White iron layer drops to 0.01mm

· Micro crack sources are extremely few

· Tool chipping edge rate drops 40%

· Tapping drilling holes does not slip thread

· Cutting receiving force fluctuation is extremely small

Processing ten several tons heavy large home appliance shell mold, interior is covered full with ejector pin holes and screw thread holes. Hole position edge happening micro chipping crack, ten thousands yuan CNC processing fee all amount becomes void.

Drilling machine worker for nickel-containing mold taps M16 deep hole thread. Tap cuts into metal interior 30 millimeters deep, torque meter shows cutting receiving force reaching 85 Newton·meters. Iron chips are by chip flute smoothly carried out.

Tough matrix material tightly bites thread tooth bottom. Assembling master uses pneumatic wrench to hit tight long reaching 120 millimeters high strength screw, thread is perfectly intact without damage, tooth opening resisted several hundred kilograms pulling tearing.

Quality inspection personnel recorded different temperatures under impact absorption work values, compiled into comparison table:

Carrying 1.5 millimeters thin wall reinforcing rib mold changed using nickel-containing material again gets on machine. 240℃ high temperature plastic and 15℃ cooling water's repeated cold hot alternation day night non-stop scours.

1200 tons injection molding machine every day 24 hours continuously spinning, counter jumped to 350,000 mold times. Stop machine using penetrant flaw detection liquid spraying at right angle intersection place, after wiping did not appear representing crack red fine line.

Nickel atoms embedded in ferrite matrix's lattice gaps inside, triggered solid solution strengthening reaction. Micro level on added a sheet full of elasticity protective net.

External mechanical force attempts to tear metal, dense micro defense lines through own extremely micro sliding, consume dropped impact brought destructive energy.

Workshop subsequently continuously tracked same batch material's injection molding lifespan data:

· Bears 200MPa peak pressure

· Thin wall insert lifespan exceeds 450,000 times

· 15℃ cold water circulation no cracks

· Ejector mechanism long-acting damage-free

In South winter no heating 5℃ factory building inside cold machine starting injection molding, ordinary mold extremely easily in first mold high pressure shooting in time happens brittle explosion crack.

Nickel-containing mold relies on micro level's toughness reserve, firmly resisted cold machine starting instant's extremely high pressure impact. Product good rate from initial 85% all the way rose to stable 99.2%.

Polishability

Polishing workshop's workbench on is supported a piece long 1.2 meters TV set front shell mold. Master's hand pinching 800 mesh silicon carbide sandpaper, dipping kerosene on steel material surface back and forth fast rubbing.

Ordinary nickel-free carbon manganese steel passing 40 hours manual grinding, surface looking already reflects light. Head top's 60 watts fluorescent lamp tube shining on mold cavity on, light spot edge presents wave-like distortion.

Magnifying glass under can see micro uneven ups and downs. Steel water solidifying time carbon element distributed unevenly, formed several micrometers big hard carbide particles and relatively soft ferrite areas.

Wool wheel carrying polishing paste at per minute 1500 revolutions speed high speed rotates. Relatively soft areas are easily cut scraped away, hard particles protrude out, leaving depth 0.02 millimeters micro pits.

Measuring roughness probe sweeping past, screen shows Ra value is 0.25 micrometers. Making ordinary plastic basin no problem, used to make high gloss black color TV set outer shell, reflection will appear blurry.

Change on a piece containing 1.1% nickel element 1.2738 steel material. Nickel atoms in smelting furnace inside put easily clumping carbon atoms forcibly dispersed open.

Cut open cooled steel block taking sample, put to 1000 times electron microscope under. Field of view inside cannot find diameter exceeding 2 micrometers coarse large carbide gathering clusters.

Hardness tester in 100 millimeters area inside continuously hits down 20 testing points. Highest reading 31.5HRC, lowest reading 31.2HRC, hardness difference is compressed to 0.3HRC within.

Polishing master anew walks one time grinding process. From 400 mesh sandpaper starting step, passing 800 mesh, 1200 mesh, finally change on containing 3 micrometers particles diamond grinding paste.

"Grinding this piece material hand feeling is very smooth, inward cutting resistance is completely same, wool wheel walking past will not have suddenly deep suddenly shallow jumping feeling, producing light speed at least fast one day and a half."

Bottom layer material physical uniformity's improvement, saved large amount polishing rework time. Record sheet on left concrete grinding work hours and consumables data:

· 800 mesh sandpaper removing knife marks work hours reduced 22 hours

· Diamond grinding paste consumption amount lowered 30%

· Ra0.05 micrometers level one time passing rate 94%

· Pockmark rework rate lower than 2%

· Optical mirror polishing cycle shortened to 5 days

Auto parts factory's injection molding machine is preparing to produce transparent polycarbonate (PC) car headlight lampshade. Specific engineering plastic's melting point is extremely high, material barrel heating ring temperature is set at 280℃.

Optical level transparent parts towards mold surface's flatness have harsh physical requirements. Headlight's light beam needs to penetrate plastic cover, light transmittance rate must reach 92% above.

If mold cavity surface hides a depth only 0.01 millimeters pockmark, 280℃ transparent plastic melt will fill full extremely small pits.

Molding exiting mold lampshade surface adds out a micro protrusion. Nighttime turning on headlight, tens of thousands lumens light beam passes through protruding part, light path happens refraction, on road surface hits out scattered glare.

Containing 1.1% nickel mold steel caught highest level SPI A1 level polishing requirement. Master uses 1 micrometer extremely fine grinding paste doing final closing tail, probe measured roughness stops at Ra 0.015 micrometers.

Mobile phone back panel mold's processing operation equally adopts nickel-containing steel material. High magnification camera surrounding decorative ring, width only 2.5 millimeters, surface requires reaching just like water surface equally flat black bright effect.

Trace nickel element steel material surface is little by little peeled away several micrometers surface layer. Naked eye looking past, polished surface can clearly reflect out polishing master's clothes on texture details.

300,000 mold times continuous high pressure production after, 1.2738 mold cavity still keeps initial mirror reflection. Not added nickel ordinary steel material hitting to 80,000 mold times, water channel nearby then will because of condensation water produce weak oxidation fog spots.

Core Comparisons

Hardenability & Cross-Sectional Hardness

Steelmaking factory made out P20 steel blocks often have five six tons heavy, thickness nearly 600 millimeters. Put in 850℃ big furnace inside continuously roasting 20 hours, mechanical arm grabs it up one handful throws into tumbling cooling oil tank inside.

Steel block skin surface 50 millimeters range meeting cold rapidly drops temperature, per minute can drop down 50℃ or so. Using hardness tester on surface knocking one time testing to see, value firmly stops at 32 HRC or so.

Towards steel block most inside looking, outside thick meat blocked heat dissipating. Reaching 300 millimeters right center position, temperature dropping speed dropped to per minute 8℃ below. Ordinary P20 only has 0.35% carbon component, inside completely cools not thoroughly.

Saw open a piece 400 millimeters thick pure P20 steel plate testing cross-section. Skin surface is 31 HRC, downward digging 100 millimeters dropped to 27 HRC, digging to 200 millimeters depth's right center, hardness tester only shows 23 even 22 HRC.

Mold factory processing depth exceeding 150 millimeters pits and holes, bottom's soft material meeting high pressure completely cannot hold:

· Milling cutter downward digging to 200 millimeters, cut out iron chips obviously become sticky become long

· Injection molding machine hitting to 50,000 mold times, bottom face side edge's wearing speed fiercely increases

· Ejector pin hole surroundings very quickly grow out 0.05 millimeters above plastic flash

· Production cycle exceeding 45 seconds deep hole parts often at bottom get stuck dead

· Polishing master in deep pit inside grinding finds sandpaper very easily slips

Steelmaking time towards furnace inside throwing in 1% pure nickel plate, whole piece steel's temper completely changed. Added this little nickel, even if thick steel block right center per minute only drops temperature 5℃, inside iron lump same can freeze solidly.

Taking a piece 500 millimeters thick giant steel block, finishing 850℃ heating and 580℃ baking. Inspector taking instrument testing cross-section, skin surface 31.5 HRC, probe piercing into 250 millimeters deepest place, hardness still has 29.5 HRC.

Workshop one machine 1200 tons strength's big machine is exactly pressing car dashboard. Mold on milled out big pit has 350 millimeters deep. Using P20+Ni dug out pit, most bottom turning corner place hardness real solid has 29 HRC.

Melted state PP plastic mixed with 20% hard glass fiber, using 120MPa extreme big pressure fiercely rushes pit bottom. Machine no day no night ran 8000 hours, disassembled down using three-dimensional measuring one time, deepest place's dimension deviation amount is tightly pressed in 0.015 millimeters within.

Front line working polishing master taking 800 mesh sandpaper manually rubbing deep hole bottom, hand feeling and rubbing surface same strenuous. CNC machine tool operator towards two kinds materials' soft hard drop gap experience most deep:

· Using deep hole drill hitting 100 millimeters hole, pure P20 discharged iron chips very smooth

· Drill bit downward walking to 250 millimeters, P20 iron chips becoming soft tangled up drill bit

· Cutting P20+Ni's whole process, machine tool spindle current jumping is less than 5A

· Taking 20R10 flying cutter head rough processing P20+Ni, blade wear is very uniform

· Drilling M16 screw bottom hole, P20+Ni must put rotation speed suppressed low to 80r/min

Home appliance factory buying 1.5 meters long washing machine inner drum mold, drawing on rigidly stipulates must use 718 steel (P20+Ni). Inner drum inside all are back and forth rubbing core-pulling small parts, deep place sliding place hardness slightly worse a few degrees, running ten thousand times then will eccentric wear 0.02 millimeters.

Digging a 800 by 1200 millimeters TV set back cover mold, back passing water cooling holes often need to hit 600 millimeters deep. In hardness only 24 HRC ordinary P20 center hitting long holes, drill bit extremely easily runs off-center breaks off.

P20+Ni from head to tail hardness is consistent, making slender gun drill hitting to bottom's skewed amount being pressed at 0.1 millimeters within. Every kilogram extra spending a little money, bought back's completely is one big iron block inside outside completely same anti-manufacturing (durable) ability.

Mold factory pulls back 3 tons heavy, 400 millimeters thick big square block steel material, one knife cutting open measuring Rockwell hardness, data again also will not appear cliff-style falling. Facing clamping force 1500 tons large injection molding machine, deep pit bottom all relies on non-discounted 30 HRC hardness holding up tens of tons internal expansion force.

Digging 50 millimeters shallow pit remote control outer shell using pure P20 is enough to deal with. Bumping into downward digging 350 millimeters car bumper, P20+Ni inside outside same hard bottom, for over millions times injection molding production caught dimension precision.

Microstructure & Polishability

Steelmaking factory coming out steel material not only looking surface how hard, cut open a small piece putting to 500 times electron microscope under, inside completely is another piece heaven earth. Ordinary P20 steel water at cooling solidifying time, inside carbon and chromium elements particularly like to clump.

Mold fitter master holding 600 mesh ruby whetstone, along same direction forcefully pushing grinding. Meeting soft hard alternating place, soft iron matrix all is ground concave in, hard carbides all protrude outside.

Master changes on 800 mesh imported Warrior sandpaper continuing back and forth rubbing, steel material interior piling up sulfides and silicates impurities this time all ran out. Taking high gloss flashlight sticking shining, mold surface all is one grain grain needle tip that big sand holes, naked eye looking past one piece piece all are bumpy orange peel lines.

Producing ordinary TV set back cover or making a router plastic outer shell, steel material rougher a little also enough to use. Later stage needing on surface doing VDI 24 level chemical etching, that little micro sand holes completely are covered by 0.05 millimeters deep leather lines. Surface roughness stopping at Ra 0.4 micrometers or so, pure P20 coping rising up very relaxed.

Steelmaking furnace inside mixed in 1% or so electrolytic nickel, steel water crystallizing process happened thorough flip. Trace nickel is like a fine dense comb, putting originally clumping carbides thoroughly broken scattered, grains' volume forcibly was shrunk three times above.

Those particularly easy to provoke trouble non-metal impurities, were uniformly diluted into extremely fine metal grid inside. Whole piece thickness reaching 400 millimeters steel billet, every square millimeter's cross-section material all became very delicate. Polishing master changing on 1200 mesh fine sandpaper, smearing on a layer W9 specification diamond grinding paste.

Wool felt polishing wheel slipping on grinding machine on, at 15000 revolutions/minute speed on cavity surface high speed spinning, P20+Ni surface will not out any material lines. Producing transparent PMMA car tail light cover, drawing indicates mold surface roughness must be pressed to Ra 0.05 micrometers below.

Workshop old master continuously fighting 40 hours, put this piece P20+Ni mirror polished to SPI A2 level, facing light looking just like a side extremely clear mirror. Two kinds materials in workshop actual grinding time, various consumables and parameters have very concrete numerical differences:

Polishing group's group leader at dispatching grinding tasks time, often according to hands on's several actual working conditions to pick drop sent coming steel materials:

· Making transparent acrylic water cup, pure P20 base polishing definitely out material lines, plastic parts waste rate exceeds 30%

· Using W3 diamond paste polishing TV set high gloss black frame, P20+Ni not easily out orange peel defect

· Electrical discharge machining after, P20+Ni surface's white bright layer thickness compares pure P20 thinner 0.02 millimeters

· Using 400 mesh whetstone rough pushing, P20+Ni's hand feeling resistance compares ordinary material bigger 20% or so

· Making MT-11010 rough etching, two pieces steel passing acid washing pool's corrosion speed differ less than 5%

Giving a side 0.5 square meters LCD TV panel mold doing full mirror polishing, purely manual's work hour fee usually exceeds 8000 bucks money. Several masters holding broken cotton cloth dipping grinding liquid back and forth rubbed tens of thousands times. If bottom layer steel material has even 0.05 millimeters impurity gathering, polished surface then will emit fog, several thousand bucks work hour fee all hit water splash.

Large car lamp factory buying injection molding machine specially hitting transparent PC lens, mold purchasing list inside all rigidly wrote clearly using P20+Ni. Melted state PC plastic light transmittance rate up to 90%, mold cavity inside even if leaves a strip 0.01 millimeters wide fine micro scratch mark, light beam hitting past light spots all are scattered.

Meeting up needing to make extremely fine wire drawing texture metal color laptop outer shell, pure P20 coarse large grains will make wire drawing texture edge present 0.05 millimeters wide saw-tooth shape micro chipping missing. Delicate uniform P20+Ni material can make 0.1 millimeters wide chemical etching lines edge keep straight sharp.

Plating layer thickness only 5 micrometers, towards bottom layer steel material's smoothness extremely picky. P20+Ni in completing 1500 mesh base grinding after, plated going up chromium layer adhesion force is extremely strong, continuously hitting full 200,000 mold times also will not happen local peeling off.

Mechanical Stress & Tear Resistance

One machine 1500 tons injection molding machine closing mold time, two pieces huge steel plates pa's one sound bump together. Cavity instantly fills full 230℃ liquid state plastic, packing pressure value instantly soars to 120MPa above.

Ordinary P20 coping 100,000 times below normal tasks still can hold. Meeting up carrying a bunch 0.5 millimeters thick thin sheet bone positions or 90 degree right angle structure complex parts, sharp parts enduring alternating stress far exceeds ordinary material's physical limit.

Laboratory cutting down a root 10x10x55 millimeters pure P20 standard spline doing Charpy impact testing. Heavy pendulum smashing down, dashboard on's impact work often only stops at 15 to 18 joules. Putting in injection molding workshop, weak parts running a 80,000 mold times then start to grow out micro metal cracks.

Crack along 0.02 millimeters gap towards inside extending, ejector pin back and forth bumping several thousand times, mold on again thin again high sharp corner pa's one sound then chipped off a piece notch. Pressed coming out plastic part edge immediately adds out a piece 3 millimeters long ugly burr.

Added 1% nickel P20+Ni steel water solidifying after, internal iron atoms' arrangement becomes very have toughness. Same taking going cutting strips doing pendulum breaking testing, instrument measuring coming out impact absorption work firmly crosses 25 joules scale line, anti-pulling breaking ability real solid rose a big chunk.

Workshop fitter monitor Old Liu often holds magnifying glass checking retired coming down molds: "Not added nickel material running long, turning corner place all is one thread one thread spider web cracks, putting machine pedestal on pressing hundreds of thousands times, sharp corner place slightly receiving a little offset force then drops slag."

Digging car front face air intake grille mold on, densely packed all are 2 millimeters wide, 80 millimeters deep grid bone positions. Melted ABS plastic every day 24 hours at 800 millimeters/second speed towards gaps inside desperately squeezing.

Two kinds steel plates in long time coping violent injection molding tasks time's difference is very concrete:

· Continuously enduring 150MPa injection internal pressure, pure P20 right angle place at 100,000 mold times or so produces plastic deformation

· Running finish 300,000 mold times, P20+Ni's bumping penetrating face gap still can lock dead in 0.015 millimeters within

· Using 5 tons overhead crane hoisting happening bumping, pure P20 edge easily bumps off a small piece triangle iron

· Repairing P20+Ni mold conducting argon arc welding bottoming time, surroundings extremely rarely appear 0.1 millimeters wide after-welding cold cracks

· Making 0.8 millimeters thick mobile phone shell, P20+Ni's fine thin inserts breaking rate compares ordinary material lowered 40%

Putting a set 8 tons heavy iron lump from machine pedestal on disassembling down, pulling to fitter table conducting grinding, welding, anew getting on CNC machine tool running programs. Back and forth one tossing, whole 48 hours workshop production capacity all soaked soup (wasted).

Home appliance factory making washing machine transparent viewing window base, 12 pieces diameter only 3 millimeters slender pushing tubes everyday in mold inside high speed pulling inserting. Ordinary P20 using not reaching two months, tube hole edge is alive alive ground big 0.05 millimeters, hitting coming out products all are scraping hands flash.

All changed into P20+Ni material, extremely strong anti-cracking and anti-fatigue ability tightly guarded fragile fine holes. Machine pedestal one year running finish 400,000 mold times delivering goods, repairing mold master using internal diameter micrometer measured one time, hole diameter enlarging dimension even 0.01 millimeters all not reaching.

Repairing mold room's argon arc welding machine consumables book on wrote very clearly, using 718 steel's several sets large car bumper molds, continuously worked three years, cavity edge repairing welding times adding up one hand all can count finish.

Meeting up electrical discharge machine tool doing discharging processing, electrode copper male in cavity inside explodes out tens of thousands degrees high temperature. P20+Ni bottom inside carrying that little nickel, puts suddenly hot suddenly cold producing internal pulling tearing force completely resolved, discharging surface extremely hard to form 0.005 millimeters deep micro dark cracks.

Large double color injection molding operation inside, mold often needs to in 20 seconds within complete 180 degrees flipping closing. Moving mold and fixed mold on's hundreds locking blocks everyday mutually bumping several thousand times. P20+Ni's high toughness guaranteed hundreds friction faces absolutely will not sudden chipping edge.

When to Upgrade to P20+Ni

Cross-Section Thickness Exceeding 400mm

Steelmaking factory putting a piece thickness 500 millimeters ordinary P20 steel block stuffed into 850 degrees fire furnace burning thoroughly, taking going throwing into 20 degrees oil tank dropping temperature. This lump weighing reaching 3 tons iron lump is too thick, outer surface instantly cooling thoroughly reaching 32 HRC hardness. Heat wants from half meter thick interior to dissipate out extremely difficult, center part's temperature dropping speed per second not reaching 3 degrees.

Carbon atoms in slow temperature dropping inside completely scatter open, a piece steel material cut open after interior is like ordinary raw iron strip equally soft. Holding ultrasonic detecting instrument sticking on cut face walking inward 150 millimeters, screen on's hardness reading all the way drops to 24 HRC. Mold factory received order wanting using this piece material digging out car bumper mold cavity, milling cutter downward crazily digging away 200 millimeters deep iron chips.

Cutter head touching heart part that layer softest metal, originally should hard anti-pressure mold cavity bottom plate fundamentally cannot eat holding high pressure. Heavy injection molding machine pedestal using 120 megapascals pushing force putting 280 degrees boiling hot molten plastic tightly pouring into deep cavity. Every inch soft bottom plate is enduring several hundred kilograms outward expanding tearing force.

· Enduring high pressure injection time bottom plate backward yielding 0.05 millimeters

· Continuously fiercely hitting 3000 mold times appearing permanent collapsing concave pits

· Produced coming out plastic parts dimension outward running off 0.15 millimeters

· Closing mold dividing boundary gap being alive alive squeezed out 0.08 millimeters thick flash

Fushun Special Steel's workshop changed formula, towards 1 ton boiling hot iron water inside pouring in 10 kilograms pure nickel plate, brand number becomes 1.2738. Nickel element like strong glue equally dragged held internal micro structure's softening speed, forcibly put temperature dropping time limit pulled long two times. Again put 500 millimeters thick nickel-containing steel block thrown into oil tank, even if center point temperature dropping slow to per minute 15 degrees, hardness equally can lock holding.

Inspector holding hitting point instrument along profile towards deep place testing, pushing advancing to 250 millimeters deepest place center point, LCD screen on's number stops at 31 HRC. Whole half meter thick solid big iron block, from outside one layer skin to most center, hardness drop gap less than 1.5 HRC. Home appliance factory purchasing 720 millimeters thick material making 65 inches TV back shell, deep digging 250 millimeters after exposed bottom face hard as initial.

Operating machine worker putting feed speed set at per minute 1100 millimeters crazily gnawing nickel-containing steel material, milling machine's spindle motor ammeter often tops at 85 amperes red line on. Sharp blade consumption amount compares normal times extra out 4 boxes, exchanging coming is cavity bottom plate in facing 100 megapascals internal impact time absolutely still.

· Nickel-free steel heart part tapping M12 thread machine tool smooth one passing to bottom

· Nickel-containing steel heart part tapping must halfway retreat chips preventing tap breaking off

· Distance surface 400 millimeters hitting holes taking samples doing anti-pressure stretching testing

· Grain size rating passing microscope magnifying dead guarding 8 level bottom line

15 degrees cold water in mold interior water pipes inside crazily circulating, surface instantly is by 260 degrees boiling hot plastic covered. 8 tons heavy huge mold in cold hot alternation inside hard carrying down 450,000 mold times scouring, deepest place snapping buckle slot position dimension deviation firmly pinched in drawing specified 0.03 millimeters inside.

High Gloss & Complex Etching Texture

Mold room's polishing master pinching 3000 mesh Warrior sandpaper, dipping kerosene on ordinary P20 steel block surface back and forth pushed 8 hours. Strong light flashlight sticking metal surface illuminating, polished face on densely packed all are 0.02 millimeters big needle holes. Ordinary nickel-free steel material in smelting time contains about 0.030% sulfide impurities, they like micro sand gravel hiding in ferrite inside.

Meeting high brightness car tail lights or transparent acrylic outer shell orders, ordinary steel material's bottom cannot support high level mirror effect. Wool wheel carrying 5 micrometers level diamond grinding paste at 15000 rpm rotation speed high speed spinning, high temperature puts surface layer relatively soft matrix planed away.

Fushun Special Steel in smelting 1.2738 steel water time, using 10's negative 3 power Torr vacuum degassing equipment putting impurities outward pumping. Sulfide content is suppressed at 0.005% below, 1% pure nickel element beat scattered carbides' piling up clumping. In 500 times metallographic microscope under, metal interior presents extremely uniform fine needle shape bainite micro structure.

Change on containing nickel 1.2738 steel material, polishing master changing using 8000 mesh diamond paste again pushing 12 hours. Surface roughness meter's probe scraping passing metal, screen on jumping out Ra value stops at 0.05 micrometers. Light hitting on mold surface refractive index reaching 98%, completely conforms SPI standard inside A2 level mirror requirement, demolding's transparent parts do not have any material lines flaws.

· Nickel-free steel material polishing 40 hours after waste rate approaches 15%

· Nickel-containing steel material polishing to Ra 0.05 micrometers only needs 22 hours

· Polished face in 300 degrees high temperature plastic scouring under not losing gloss

· Anti-rust oil wiping after placing 15 days did not appear oxidation black spots

Chemical etching texture workshop facing ordinary P20 steel material will meet more thorny situation. Worker puts adjusted prepared 5% concentration nitric acid solution splashed on mold surface, acid liquid starts corroding metal. Because nickel-free steel interior hardness high low uneven, soft place is by acid liquid bitten down 0.08 millimeters, hard place only bites in 0.03 millimeters.

Making car dashboard's VDI 3400 standard 36 number leather texture, requires surface all is uniform coarse sand grain effect. Taking ordinary steel material bitten out leather texture, using 20 times magnifying glass looking, deep shallow not one pits causing light diffuse reflection thoroughly loses control. Injection molded coming out plastic part surface, east one piece shining, west one piece darkening, like grew white spots.

Acid liquid at 1.2738 steel material surface's corrosion speed maintains at per minute downward biting 0.005 millimeters. Soaking 3 hours fishing out washing, three-dimensional micro instrument scanning bottom leather texture pit holes, depth error is clamped in 0.002 millimeters within.

Large car workshop pulling away interior parts mold conducting batch production. Long reaching 1.5 meters dashboard mold cavity is covered full fine dense lychee texture, 150 tons heavy injection molding machine pressing in 260 degrees modified PP plastic. Demolding after gloss meter sticking on plastic part surface testing, 60 degrees angle under gloss data whole board stable at 3.5 GU.

A set making cost 400,000 home appliance transparent panel mold, early stage saved 3000 bucks money going buying ordinary nickel-free steel material. Injection molding out 5000 pieces transparent parts light transmittance rate only 85%, defective products all are returned smashed anew making granules. Changed into 1.2738 steel material anew opening mold cavity, light transmittance instrument hitting out value firmly stands on 92%.

Polishing room single piece mold reduced 60% rework time consumed, not needing repeatedly supplementing hitting diamond paste. Chemical plant adjusting acid liquid master also no need taking cotton swab going dotting coating 34 HRC hard point areas. 20 liters nitric acid pouring down maintaining 45 minutes reaction time, 1.2738 surface popping out micro white bubbles, washed out texture and drawing strictly seamlessly fitting.

Production Volume Exceeding 500,000 Mold Times

One machine 800 tons Haitian injection molding machine at 15 seconds one cycle continuously spinning rotated two months. Counter jumping to 320,000 mold times time, ordinary P20 mold parting face edge is by high pressure plastic scoured out a strip 0.12 millimeters fine micro depression.

280 degrees molten ABS plastic in screw pushing under, carrying 110 megapascals huge pressure impacting mold cavity. Ordinary nickel-free steel material's yield strength at 850 megapascals or so. Tens of thousands times violent impact under metal still can carry holding, exceeding 300,000 times fatigue critical point, edge metal crystal lattice starts happening cannot recover plastic deformation.

Repairing mold master pulling stopping machine pedestal, putting 5 tons heavy mold disassembled down hoisted into repairing room. Holding argon arc welding machine at collapsed fallen edge supplementing on 0.5 millimeters high welding wire, sending to machine tool on anew milled flat. One going one returning delaying 48 hours, workshop lost 11500 pieces washing machine panels' production capacity, delivery date backward extended two days.

Steelmaking furnace inside formula changed into 1.2738, adding in 1% pure nickel blocks. Nickel atoms dissolving into ferrite matrix inside, putting material yield strength forcibly pulled high to 980 megapascals. Same 32 HRC hardness, nickel-containing steel material facing 110 megapascals high pressure plastic scouring, crystal lattice arrangement tightly bites together.

Workshop equipment maintenance record book on writing: nickel-free material 300,000 mold times must get on machine pedestal welding supplementing corner, nickel-containing material 600,000 mold times only needs whetstone slight grinding removing dirt.

Injection molding machine's mechanical arm one day grabbing 5760 times products, mold inside 20 degrees cooling water and 280 degrees high temperature plastic alternately attacking metal surface. Counting panel on red numbers crazily jumping, all the way soaring crossing 500,000 mold times big pass.

· Parting face biting gap still controlled at 0.02 millimeters below

· Cavity bottom polished face gloss only drops 3%

· Deep reaching 150 millimeters rib position slots did not appear metal fatigue inward shrinking

· Closing mold instant measured anti-pressure yielding amount not fully 0.005 millimeters

Inspector spot checking number 500,012 piece product, caliper measured out dimension tolerance pinched in 0.03 millimeters extreme difference band inside. Machine pedestal does not need stopping machine, operator towards material hopper inside dumping 25 kilograms one bag plastic granules. Planned prepared spare mold was cancelled, factory inside saved 120,000 yuan new opening mold budget.

Mold interior densely distributing 80 roots ejector pins, everyday in guide sleeve inside back and forth rubbing tens of thousands times. Ordinary steel material's hole wall passing 400,000 times rubbing, hole diameter is ground big 0.08 millimeters, ejector pin gap outward leaking seeping plastic liquid. 1.2738 steel material extremely high anti-fatigue wearing ability, lets hole diameter enlarging value stop at 0.015 millimeters.

Order requiring delivering 800,000 pieces products. Using nickel-free material factory manager must at quotation sheet on sharing two sets molds' cost, reserving 3 times big repair's 50,000 yuan maintenance fee. Chose nickel-containing steel material, from first mold trial producing to number 800,000 mold delivering goods, this piece 8 tons heavy big iron lump even injection molding machine's pressing plate all did not go down passing.

Mold cavity four corners' locking mold plates enduring huge closing mold tension. Hundreds of thousands times pulling tearing lets nickel-free steel screw hole positions produce micro level cracking, tension meter showing thread biting force dropped 22%. Nickel-containing steel's toughness absorbed enormous mechanical vibration, 800,000 times opening closing after thread anti-pulling strength still maintains at initial value's 95% above.

Night shift worker every interval 12 hours towards guide pillar on smearing a handful 5 grams butter. Huge iron steel up down opening closing, emitting dull powerful bumping sound, nickel-containing steel material at several hundred tons clamping force under caught all consumptions.