Welding Cracks in P20 vs P20+Ni | Mold Repair & Pre-heating Guide

Suggest adopt low-hydrogen welding rod, current 80–120A, small current multi-layer build-up welding, welding after slow cooling, and conduct 550℃ tempering eliminate stress.

Mold Repair

Cracking & Material

P20 steel material inside loaded 0.38% to 0.45%'s carbon, mixed on 1.5%'s manganese and 1.7%'s chromium, according to industry rule calculating this pile material's carbon equivalent broke through 0.85. P20+Ni extra added 1%'s nickel, carbon equivalent approaches 0.95's red line. Temperature drops through 350 degrees Celsius this martensite phase transformation point time, metal block's volume suddenly expands 4% around.

Mold solid core thickness exceeds 150 millimeters, surface layer and inner core per second pulls open 5 degrees Celsius's temperature difference. Outer shell cools thoroughly becomes hard, internal slow swallow swallow towards inside shrinks, two strands opposite direction's force instantly tears break steel material 600 Megapascals's bear bottom line.

Factory building air inside even if mixed with a little little water vapor, bumps into 5000 degrees Celsius's electric arc spark, instantly by roasted into active's hydrogen atoms. Micro small's hydrogen atoms extremely tricky, desperately towards just solidified's metal gaps deep place drill.

Head one day takes liquid medicine does coloring flaw detection entirely no flaw, takes mold put on 24 to 72 hours, internal's micro small crack opening by hydrogen gas vividly pushed open. Workshop inside occasionally hears one sound crisp's metal break sound, crack long ago followed internal eaten entered 10 millimeters deep.

Block stop air inside's free hydrogen drills empty holes, start hand brings a little ruthless strength:

· Welding rod stuffed into oven adjusted to 350 degrees Celsius stifles 2 hours

· Workshop air humidity dead dead pressed at 60% below

· Opening groove two sides 20 millimeters uses high purity acetone wipes dry smudges clean

· Blown out's argon gas purity cannot be lower than 99.99%

P20+Ni inside added's that 1%'s nickel indeed endures crashing, incidentally takes metal transfers heat's speed vividly dragged slow 15%. Oven sprayed out's heat wave towards P20+Ni big iron block deep place drills's progress, compared to normal P20 slow a big section.

Takes 500 kilograms heavy's P20+Ni big mold base stuffed into furnace roasted to 250 degrees Celsius, furnace fire fully opens must endure full 8 hours. Following normal P20 that set 6 hours's old rule manages, mold most center only reluctantly touches 180 degrees Celsius's warm swallow water state.

Center zone differs 70 degrees Celsius's cold hot account not calculated clear goes strikes fire, sesame big's iron water pool instantly soars to 1500 degrees Celsius above. Beside big piece not hot thorough's raw cold iron block, like tightening hoop curse same dead dead stuck holds that little iron water's natural expansion.

Collect fire after's natural temperature dropping stage, iron water from 800 degrees Celsius drops to 500 degrees Celsius this section time (industry inside calls t8/5) became grab life's gate pass. Temperature dropping time runs not wins 12 seconds, soft a little's austenite comes not in time changes body, all frozen became hard bang bang, crisp raw raw's martensite.

Think ways figure methods takes temperature dropping time pulled long, hand foot kung fu all in details inside:

· Takes 8 to 10 millimeters thick's aluminum silicate insulation cotton takes four surroundings wraps into big zongzi

· One layer one layer towards up piles iron water, temperature drops breaks 200 degrees Celsius absolutely stops hand

· Every layer welded on's iron skin thickness stuck dead in 1.5 to 2.0 millimeters

· Find big size block wind board takes through hall wind pressed to per second 2 meters inside

Worker master picks up per minute vibrates 3000 times's pneumatic hammer, taking advantage of iron skin from dark red fades into gray white's 20 seconds empty gap, facing hot hand's surface a bout crazy knocking.

Round head tungsten steel hammer smashes out up hundreds connected into pieces's concave pits, surface by knocked out 0.5 millimeters deep's fish scale lines. Originally towards inside dead life shrinks's pulling force, by external force forcibly hammered became towards outside paved open's anti-pressure strength road, self-bringing's internal consumption force at least offloads drop 40% to 60%.

Shaking ears's knocking beating does finish, mold stomach inside left has 150 degrees Celsius's bottom heat, hurriedly let crane hoists enters big size oven goes walks one circle deep processing. Furnace inside's fire condition presses per hour 40 degrees Celsius's turtle speed towards up climbs, touches to 550 degrees Celsius dead dead fixes hold, dry consumes 4 to 6 hours.

Inside those prick people provoke disaster's hard thorns, by high temperature slowly simmered to submit submit settle settle, scatter scatter fall fall. Most easy breaks opening's place, hardness quietly no sound no breath slides to HRC 35 's safe steady zone, with beside good iron's hardness difference by forcibly pinched merged to HRC 2 inside.

Welding Repair Craft

Argon arc welding gun front end probes out that root 2.4 millimeters thick's thoriated tungsten electrode, leaving steel board surface dead dead stuck holds 2 millimeters's suspended empty distance. Finger buckles down switch, 15 liters/minute's pure argon gas sprays out, takes surrounding air discharged to one clean two net.

Adjust machine panel on's current knob stuck in 80 amperes to 120 amperes's narrow gap inside. Fire slightly big a little, iron water pool instantly digs out exceeds 3 millimeters's deep pit, underneath's good steel all by stirred into a pot porridge.

Iron water pool's width controlled at 3 millimeters sticking out head, welding wire follows edge a little little towards inside sent. Pinched in hand inside's ER-P20 special purpose welding wire picked is 1.6 millimeters diameter's fine wire, rather a little little paves, also absolutely not uses 2.4 millimeters's thick wire goes hard fills area.

Every fills enters one drop iron water, wrist brings out extremely small amplitude's Z character shape swinging, swinging range not exceeds 4 millimeters. Heat amount by evenly spread thin on surface, most bottom down one layer towards base material's melt through depth dead dead bites holds 1.5 millimeters's surface skin, absolutely not towards deep place extra walks one point.

Repairs finish one pass long strip, puts down welding gun takes temperature measuring gun sticking beside one sweep. Originally 200 degrees Celsius's iron board by roasted to 280 degrees Celsius above. Master throws down tools goes beside smokes root cigarette, hard waits temperature drops back 250 degrees Celsius's red line just dares continues receives work.

Underneath's parameters table is workshop inside endured out's hard rules:

Table inside's numbers only manages machine, human hand underneath's kung fu still must look fills pit's order:

· First takes 1.2 millimeters fine wire at U shape groove most bottom down's turning corner walks one circle, fills flat two sides not reaching 2 millimeters's dead corners

· Transition layer changes uses 1.6 millimeters welding wire pressing previous one pass's three parts of one covers towards up, crossing overlapping place cannot leave one thread gap

· Stacks to third layer must stop hand, sprays on red white two colors's penetration flaw detection agent dead stares looking 5 minutes

· Covering face layer compared original surface high out 1.5 millimeters then can, leaves for machine tool goes mills flat

Flaw detection agent at edge corner reveals out one stripe even if only has 0.5 millimeters's red line, front's work all must push down anew comes. Picks up angle grinder changes onto 60 grit's louver blade, facing red line towards down deep digs 2 millimeters, straight until red mark disappears to no shadow no trace.

Bumps into mold deep cavity inside not reaching 10 millimeters wide's narrow groove, conventional welding gun's porcelain mouth stuffed not goes in. Tears down standard configured's 10 number porcelain mouth, changes onto custom made's 6 number added long type transparent glass cover, field of vision by forcibly expanded 40%.

Tungsten rod stretches out length from normal's 5 millimeters pulled long to 8 millimeters, relying on pulse current maintains that stripe slender's electric arc. Pulse frequency adjusted to per second jumps moves 2 times, electric arc one strong one weak alternates, iron water one bright one dark follows crystalizes.

Strong current 110 amperes melts open iron water, weak current maintains at 30 amperes not lets fire extinguishes. High temperature melt pool had half time goes gasps rests drops temperature, heat amount input by cut drop 30%, narrow groove two sides's thin walls just will not on the spot burns through.

Bumps into P20+Ni material on by hard object smashed out diameter 5 millimeters, deep reaches 8 millimeters's deep pit loophole. Pit bottom first paves one layer 1 millimeter thick's pure nickel bottoming welding wire, relies pure nickel extremely good's ductility goes grabs firm bottom material.

Nickel wire bottoms finishes bottom, top surface continues uses P20 same material welding wire one layer layer towards up covers. Not same components's iron water at junction place mutually bites merges, relying on 1500 degrees Celsius's high temperature mutually penetrates enters inside approximately 0.05 millimeters's depth.

Repairs waterway beside's cracking more lets people pinches handful sweat. Cooling waterway leaves welding seam remains not reaching 8 millimeters's flesh thickness. Uses 130 amperes's big fire continuously burns 5 minutes, steel board back side's waterway inner wall on the spot will by roasted out one layer black black's oxidation skin.

Waterway wall rises skin, mold's cooling efficiency immediately hits a eighty percent discount. Operating worker changes uses segmented backwards retreating welding's method, first from left side towards right welds 20 millimeters, breaks open electric arc rests a while, runs goes right side towards left repairs 20 millimeters.

Repairs mold sharp's cutting edge position, current suppressed at extremely low's 60 amperes. Hand on's walk gun speed lifted to per minute 15 centimeters, spark sweeps past, iron water just hangs on 0.8 millimeters thin thin one layer just withdraws fire.

Repairs knife edge speaks of sees good just collects, extra leaves one second clock, sharp's edge will at 3000 degrees Celsius's electric arc under burns collapses. Leaves down one layer bringing radian's micro convex margin, hands over by CNC processing center with per minute 8000 revolutions's milling cutter slowly scrapes flat.

Workshop corner piles dozens dozens scrapped welding material heads. Opens seal uses not finishes's ER-P20 welding wire, at humidity 65%'s air inside exposed exceeds 4 hours, immediately by thrown enters waste material bucket, absolutely not brings enters tomorrow's work account.

Standard Operation Steps

Gun mouth clamps a root 8 millimeters thick's copper plated carbon rod, dial panel current knob one handful twists to 350 amperes's scale line on. Fire light bringing high pressure air flow sprays goes out, follows hair silk same's crack all the way towards down deep digs, turns eye at steel board on plows out one stripe 12 millimeters deep's groove.

Fire sparks scatters exhaust, groove two sides leaves down thick thick one layer black gray color's oxidation crust. Changes onto rotation speed 11000 revolutions/minute's heavy type angle grinder, installs on 40 grit's resin grinding wheel piece sticking edges back and forth gnaws. Black skin by one layer layer scraped drop, straight until concave groove bottom part reveals out bringing has metal luster's pure silver white color, two sides groove vividly ground into standard's 75 degrees U shape included angle.

Leaves down even if 0.1 millimeters deep's oxidation black skin goes strikes fire, iron water inside accurately will pop out sesame big's dense air holes.

Merely relying on naked eye looks not enough bottom gas, must take red white two colors's DPT coloring penetrant takes bottom flips one pass. White color's developer sprays full whole U shape groove, waits on full full 15 minutes goes absorbs possible hiding at deep place's red water. White color powder surface on clean clean clear clear reveals not out half point red blood silk, just dares goes tools cabinet inside flips finds K type thermocouple temperature measuring wire.

Temperature measuring probe cannot casually find a flat ground takes adhesive tape one sticks finishes matters. Electric drill installs on 3 millimeters's twist drill bit, at leaving concave groove edge 25 millimeters's position towards down hits a 5 millimeters deep's blind hole. Thermocouple's probe real hits real stuffed enters hole bottom, outside pastes on one layer heat resists 1200 degrees Celsius's high temperature ceramic mud dead dead seals holds, wire head connects on temperature measuring instrument.

Reading table on red color's liquid crystal numbers jumps moves, stuck at 245 degrees Celsius no longer towards up climbs. Feels out white clean cloth pours on purity 99.5%'s industrial acetone, surrounds groove up down 20 millimeters's area uses force wipes washes. Pure acetone volatilizes extremely fast, brings away fingerprints and air inside drops down's tiny point oil film. Starts hand's rules tolerates not gets hits discounts:

· Wears on no powder nitrile gloves goes takes welding wire

· Pure cotton wiping cloth wipes finish groove absolutely not turns head rubs second pass

· Acetone bottle mouth leaves fire source maintains 5 meters above distance

· Wipes finishes airs dry's time pinched at 60 seconds inside

Welding gun presses low, 2.4 millimeters's tungsten electrode faces aligns groove most deep place's dead corner hits out first pass fire arc. First pass bottoming's iron water speaks of thin and penetrates, eats enters base material's depth stuck at 1.5 millimeters's red line on. Melt pool's width dead dead pressed at 4 millimeters inside, wrist brings welding gun with per minute 8 centimeters's uniform speed towards front flatly pushes.

One root 330 millimeters long's welding wire burns finishes one big half, collects arc's instant takes current slowly towards down drops, drags out long long's tail prevents collects out volcano crater. Just paves good's this stripe iron water suffuses eye piercing's red light, temperature less says at 800 degrees Celsius up down.

Beside waiting's apprentice one handful pinches accurate 20 seconds's window period, swings up half jin heavy's round head pneumatic knocking hammer smashes towards up. Tungsten steel makes's hammer head bringing per minute 3500 times's high frequency shakes swings, facing red hot's welding seam one bout fierce hammer.

Knocking's strength must takes convex rises's welding flesh smashes flat three parts of one, hard takes towards inside shrinks's strength squeezes goes out.

Digital temperature measuring instrument on's reading drops to 210 degrees Celsius, hand inside's welding gun must suspends at half empty waits. Hot wind machine framed at beside facing mold fiercely blows on dozens minutes, liquid crystal screen on's numbers difficultly climbs past 240 degrees Celsius, just dares continues paves second layer. This layer layer stack stack's rules all at thickness on compares strength:

· Second layer transition flesh thickness not exceeds 2 millimeters

· Two passes welding seams's overlapping amount covers holds front one pass's three parts of one

· Every stacks two layers takes steel wire brush takes surface's silicate dregs scrapes clean

· Edge bites flesh's place extra stays 0.5 seconds fills full dead corners

Groove fills flat after, extra piles out 1.5 millimeters's margin leaves for back pass working sequence goes mills. Mold body on's remaining temperature still remains 200 degrees Celsius, factory building top on's 5 tons level crane already hung good lifting belt. Crane takes this piece steel pimple steady steady puts enters heating furnace, thick heavy's furnace door boom rumble one sound smashes down, isolates outside 20 degrees Celsius's cold air.

Furnace inside's resistance wire connects on electricity, following per hour 45 degrees Celsius's slow rhythm towards up adds heat. Rises to 520 degrees Celsius dead dead fixes holds, timer dials to 4 hours's scale. Annealing's time one little little consumed exhaust, cuts off power source lets mold at furnace bore inside stifles on 12 hours, following furnace temperature slow swallow swallow drops back room temperature.

Door opens, pulls out mold takes hand-held type Leeb hardness tester goes inspects goods. Probe presses at welding seam exact center "pa" ground hits one down, screen jumps out HRC 34's reading. Probe towards beside moves out 30 millimeters presses at old material on again hits one down, displays HRC 32.

Two sides's hardness difference dead dead bites at 2 degrees inside, CNC milling machine's cutter head cuts towards up just will not slip breaks edge. Master picks up sandpaper takes hit past hardness's spots rubs bright, smears on one layer anti-rust oil, this pass at steel board on moves knife's work just counts delivers matter.

Furnace temperature retreats exhaust's surface suffuses one layer dark cyan color's oxidation film. Workshop outside's trailer reverses enters big door, chain lock buckle pierces through mold two sides M30's lifting ring holes. Crane pulls straight lifting belt, accompanying motor muffled's operation sound, this piece carried past thousands degrees high temperature roasting's P20+Ni steel board by steady steady placed on truck bucket, sent towards next one pass mechanical processing's working station.

Pre-heating Guide

Pre-heating's Necessity

Welding gun nozzle pops out electric arc's that one second, center area temperature crazy soars to 3200 degrees. Tightly leaning against welding seam 15 millimeters opens outside's steel board, often still stays at 25 degrees's room temperature. High reaches 3175 degrees's huge temperature difference, all squeezed in a big thumb wide's gap inside. Steel material's heat conductivity coefficient normally only has 42 W/(m·K), heat amount fundamentally comes not in time scatters open.

Approaching melting area's metal by dead life towards outside pulled tears. Every raises high 100 degrees, one meter long's P20 steel material just wants to expands 1.2 millimeters. Outer circle cold ice ice's metal like iron hoop same dead dead stuck holds expansion area. Inside's pulling tearing force instantly breaks through 900 Megapascals.

P20 exiting factory's yield strength calibration line at 850 Megapascals up down. Pulling force numerical value once crosses over this stripe red line, steel board just will from inside to outside by vividly torn open. Takes a few tons heavy's mold pushes enters industrial constant temperature furnace roasts to 300 degrees, two sides's temperature drop by forcibly wiped flat near ten parts of one.

Violently crashing's cold hot boundary starts becomes flat gentle, internal stretching pulling force drops back safe's 400 Megapascals around.

· Normal temperature 20 degrees: Internal crystal lattice located at sleeping state

· Receives heat 300 degrees: Expansion shape deformation offsets 30% pulling tearing force

· Local part 800 degrees: Austenite happens violent phase transformation

· Electric arc 3200 degrees: Metal physical boundary completely melts

Becomes liquid state's mold steel, every 100 grams one mouth breath swallows down 30 milliliters hydrogen gas one point all not wastes force. Waits temperature drops back normal temperature, metal internal's stomach seriously shrinks water, most only can load down 2 milliliters.

Extra comes out's that 28 milliliters hydrogen gas, by dead dead closed in metal micro small's crystal lattice gaps inside. Hydrogen atoms extremely small, diameter measures out only has 0.1 nanometers, at 20 degrees's environment inside runs compared snail still slow. Hundreds up thousands hydrogen atoms spends on a few weeks time, slowly gathers to together becomes one big lump hydrogen molecules.

Inside's air pressure one road soars up to 100 standard atmospheric pressures. At naked eye fundamentally looks not see's microscopic gaps inside, huge's internal air pressure passes a few weeks just can vividly push out quite a few millimeters long's cracks. Takes environment temperature maintains at 250 degrees above, microscopic world inside hydrogen atoms' running speed one down stroke pulls high 50 times.

High temperature gives hydrogen atoms towards outside running away's huge kinetic energy.

· Melt pool solidifies before: 90% free hydrogen follows air flow runs drop

· Drops temperature to 300 degrees: Residual hydrogen with 0.5mm/s towards outside seeps

· Maintains temperature 120 minutes: Deep layer crystal lattice inside's hydrogen basically clears empty

· Room temperature 20 degrees: Molecule activity stops comes down gas by sealed dead

Looks at cooling speed dial panel, per second dropping temperature 5 degrees is a extremely dangerous boundary. Cold ice ice's steel board sucks heat extremely fast, not handled past's heat affected zone, temperature according per second 15 degrees even 20 degrees' speed towards down drops. Carbon atoms fundamentally comes not in time runs back original's position, rawly stiffly stuck at crystal lattice exact middle.

Originally neat neat tidy tidy's body-centered cubic structure, all by squeezed into twisted's body-centered tetragonal structure. Following together comes's still has 4.3%'s local volume expansion rate. Takes microscope goes looks, heat affected zone densely packed densely packed all is needle point same's martensite. Uses Rockwell hardness tester goes hits points tests, reading from normal's 32 HRC one road soars to 55 HRC.

Bumps into 55 HRC so high's hardness, casually knocks two downs, edge just will drop down a few millimeters's metal broken dregs. Added 1% nickel element's P20+Ni temper not too same. Continuous cooling transformation curve towards right side big amplitude moves a whole whole one time order of magnitude.

Even if dropping temperature speed slow to per second 8 degrees, that layer hard bang bang's martensite same as before not receives control ground crazy grows. Bottom temperature only can forcibly pulls high to 350 degrees above, takes dropping temperature curve hard presses at per second 3 degrees inside. Welding gun towards front walks one centimeter, inputs enters inside's heat amount approximately is 1500 Joules.

Thickness reaches 150 millimeters's large type car bumper mold, scatters up heat comes like one piece huge's ice sculpture.

· Bigger than 15 degrees/second: Grows full high hardness's crisp martensite

· 8 to 10 degrees/second: Martensite and bainite mixes at together

· 3 to 5 degrees/second: Grows out solid's lower layer bainite

· Smaller than 1 degree/second: Crystal grains becomes too big extremely not endures wearing

Bottom layer welds out's metal just solidifies, surface's temperature not reaches two minutes just drops back 150 degrees. Grinding machine per minute 12000 revolutions flies speed rotates, grinding wheel piece cuts rubs out's micrometer level heat amount, enough lets super hard embrittlement layer surface floats out one piece hair silk same's fine lines.

Injection molding machine closes mold smashes down comes just is 800 tons' physical lock mold force. Dozens micrometers's small fault, instantly by amplified into pierces through whole mold cavity's scrapped big cracking marks. 2 tons heavy's mold base placed at work table on, underneath steel board temperature just 22 degrees.

Heat amount follows steel material's texture towards four surroundings flies speed conducts, one second clock draws away almost 400 calories heat energy. Takes roasting gun facing aligns one place fiercely burns 5 minutes, towards down 3 millimeters deep's place, thermometer reads out reluctantly just 50 degrees. Outer surface's hot metal towards outside expands 0.3 millimeters, underneath's cold metal one moves not moves.

Cold hot junction's place, crystal grains wants to bear approximately 250 Megapascals's residual shearing force. Takes whole piece material pushes enters industrial furnace inside continuously roasts on 12 hours, heat wave one little little seeps enters 300 millimeters thick's steel board most center. Outside and most inside's heat amount finally reaches balance, temperature difference by dead dead suppressed at 15 degrees inside.

Parameters Setup Standard

P20 and P20+Ni at workshop inside outer appearance one mold one same, steelmaking furnace inside throws adds's metal material completely not same. Standard P20 steel material contains has 0.38%'s carbon element, paired has trace amounts chromium and molybdenum. Applies carbon equivalent calculating equation, final numerical value stays at 0.72 up down.

Line of sight turns towards P20+Ni, steel factory towards iron water inside dumps 1% to 1.2%'s nickel element. Carbon equivalent testing instrument's pointer soars rises to 0.86 above. Extra outs 0.14 carbon equivalent, whole piece mold steel meets heat extremely sensitive. Electric arc burning scorching working sequence middle, carbon equivalent once crosses over 0.6 warning line, steel board meets cold cracking probability folds times doubles doubles.

Suppresses high carbon equivalent causes's burst cracking tendency, oven setup temperature needs matches material quality. Repairs conventional P20 mold, temperature controller knob stays at 250 degrees to 300 degrees interval then can. Handles contains nickel amount high's P20+Ni, maintains 250 degrees roasting parameters, welding rod just burns finishes one half, heat affected zone will instantly breaks open one stripe 0.5 millimeters wide's cold crack.

P20+Ni's bottom line pre-heating temperature by dead dead nailed at 300 degrees above, upper limit stuck tight at 350 degrees. Forcibly pulls high 50 degrees roasting parameters, crisp hard martensite structure happens softens, transforms into high toughness bainite.

Oven panel setup as 300 degrees, not represents mold pushes enters ten minutes then can executes welding. Industrial electric furnace rises temperature power extremely high, mold steel main body sucks heat speed extremely slow. Rises temperature dial panel numbers according per hour 50 degrees's span slowly climbs rises. One piece room temperature 20 degrees, thickness 200 millimeters's solid core mold base, purely climbs rises to 300 degrees needs consumes 6 hours.

Surface reaches 300 degrees, heat amount needs continues towards iron block deep layer center seeps. Operator pinches watch calculates, steel board thickness every increases 25 millimeters, holds temperature time length forcibly accumulates 1 hour. 200 millimeters thickness's steel block, experiences 6 hours rises temperature and 8 hours holds temperature, at temperature controlled furnace inside full full stays 14 hours just can moves out.

Forcibly shortens roasting work hours, steel board surface layer burns hand, cuts open center part measures temperature not sufficient 100 degrees.

· Welding rod current pushes to 150 amperes, single root welding rod continuously burns 3 minutes

· Fills full 500 millimeters long, 10 millimeters deep's groove opening, consumes time about 150 minutes

· Exposed at 20 degrees air inside, steel board surface every 15 minutes drops temperature about 20 degrees

Welding gun at front direction sprays electric arc, infrared temperature measuring instrument's light point at side face 15 millimeters place dead dead stares holds steel board. Fills flat one stripe 500 millimeters's long crack, welder works consumes time exceeds 3 hours.

Surrounding cold air continuously not breaks draws away mold heat amount, surface infrared measuring temperature reading from 320 degrees one road slides down. Thermometer numbers drops falls to 290 degrees, handles P20+Ni workpiece needs forcibly cuts off electric arc. Mold stuffed back temperature controlled furnace inside, covers on flexible ceramic heating blanket, anew burns to 320 degrees just can continues executes welding.

Fills full last one pass welding seam, strictly forbids splashes sprinkles cooling water, strictly forbids opens turns on industrial strong fan blows. Pulls comes thickness reaches 50 millimeters's aluminum silicate ceramic fiber blanket, takes whole piece steel board wraps becomes dense not penetrates wind's square block. Strictly tightly wrapped's steel block, dropping temperature speed by physically limits at per hour 30 degrees inside.

300 degrees' mold at fiber blanket inside covers tight, needs consumes 10 hours slowly drops back room temperature. Heat amount one thread thread towards outside spills out, metal crystal lattice inside's hydrogen atoms gains extremely long's escape window period squeezes out steel board. Internal stress at micrometer level's slow shrinking inside mutually offsets, hardness tester final measures numerical value steady steady stays at 38 HRC up down.

Pre-heating Process Flow

High temperature electric arc one roasts, 0.1 grams's oil dirt will instantly decomposes out up hundreds milliliters's hydrogen gas. Angle grinder changes onto new grinding wheel, sticking old crack edges towards outside uses force grinds 50 millimeters. Taking high pressure air gun facing fine small gaps fiercely blows 3 minutes, digs drop mixing holding iron rust's fatigue layer.

Reveals out metal original's emitting bright bottom color after, pours a little purity 99.5%'s industrial acetone at dust-free cloth on. Acetone volatilizes speed extremely fast, leaves for workers' effective wiping time merely has approximately 15 seconds. Repeatedly wipes 3 passes above, straight until white color cloth surface on looks not see one thread black color powder dust trace. Groove outside 50 millimeters's zone, must thoroughly reveal out steel material internal silver white color's pure net luster.

· Equipped with 80 grit aluminum oxide sand cloth's heavy type louver blade

· Purity reaches 99.5%'s industrial level volatilizing acetone

· Rotation speed per minute 12000 revolutions' straight handle grinding machine

· Pressure set at 0.6 Megapascals' high pressure removes dust air gun

Length exceeds 1.5 meters' large type car door board mold base, must flatly steadily stuffed enters long wide each 2 meters's industrial trolley furnace inside. Furnace wall on hangs 12 roots big power resistance wires provides huge heat source. Dial panel knob cannot one twist to bottom, per hour rises temperature amplitude dead dead stuck at 60°C's scale line on. Heat amount towards 300 millimeters thick's solid core steel block deep place drills exceptionally slow.

Every 25 millimeters's thickness, just must at 300°C's furnace bore inside extra endure whole whole 60 minutes. Mold center position hits a 5 millimeters deep's physical blind hole, inserts enters one root fine long's thermocouple probe.

Outer surface skin touching burns hand, center point reading possible reluctantly passes 100°C. Fierce fire dry roasts will takes steel material surface layer burns out 100 micrometers's rough crystal layer, deep place still is 20°C's iron pimple.

Wide reaches 150 millimeters's heating belt follows welding seam walks towards, tightly tightly sticks holds ice cold's steel board. Outside again covers on one layer brings aluminum foil reflecting layer's insulation asbestos, ties tight 5 roots stainless steel ties prevents dropping falls. Connects through 380 Volts' three phase electricity, 8 kilowatts's power vividly takes one piece thick iron skin one little little roasts hot.

Reading error lightly easily easily reaches ±50°C, data completely loses reference value. Old welder pocket inside all year round packs a few roots specific temperature's measuring temperature chalk. Outer appearance with little child uses's crayon one mold one same, box on clear clear clear clear printed numbers 250.

At leaves welding point outside 25 millimeters's place scratches pulls one pass rough line. Smeared's chalk marks in two seconds clock inside melts into one puddle transparent water stain. Underneath 5 millimeters deep's iron flesh real real solid solid burned to 250°C's standard line. Environment air temperature 35°C and 15°C alternate changes illusions time, person's skin towards heat radiation's perception deviation high reaches 80°C.

· Rated melting temperature set as 250°C and 300°C's measuring temperature chalk

· Bringing strong force magnetic suction base's K type thermocouple contact type probe

· Error range controlled at ±2°C inside's digital measuring temperature table

· Measuring depth can reach 100 millimeters's physical probe

Fills full one pass 10 centimeters long's deep V shape groove needs consumes near 20 minutes time. Welder wears thick heavy endures high temperature's leather gloves, continuously burns finishes half box approximately 20 roots special use welding rods. Air convection brings away huge amount heat energy, mold edges's steel water temperature quietly drops falls to 180°C.

Multi layer multi pass welding's gap time extremely dangerous. Bottom layer steel board red to emitting bright, surface however by cold wind blows scatters heat amount, interlayer middle will vividly tears open one pass 10 micrometers wide's crack.

Oxygen and acetylene's mixed ratio precisely adjusted to 1.2 compares 1. Blue color flame tip end leaves metal face 50 millimeters not stops draws big circles. Waits until chalk at surface once again scratches out melts opens's water marks, takes temperature hard pulls back 300°C, again connects on just now not welds finishes's joint continues towards down walks finishes remaining's welding seam.

· Thickness reaches 50 millimeters's aluminum silicate ceramic insulation blanket

· Heat conductivity coefficient extremely low's dry multi holes vermiculite powder mineral pile

· Wide belt reaches 15 millimeters' heavy type stainless steel tightening firm big ties

· Monitors per hour dropping temperature amplitude not exceeds 30°C's time sequence table

Repairs welding work completes's that instant, mold whole body temperature still stays at 300°C's high position interval. Pulls past two sheets area 2 square meters's ceramic fiber blanket, takes mold strictly strictly solid solid wraps on whole whole three circles. Takes iron shovel shovels comes two woven bags dry's vermiculite powder, takes metal outside deep buries enters inside 20 centimeters thick. Experiences 10 hours's long long stifles furnace dropping temperature process, one lump raw iron finally flat steady drops falls back 25°C's safe room temperature.