The Jiang Ren of Cr12MoV steeliness mould changes processing

Summary: High temperature of classics of Cr12MoV steeliness mould moves qualitative, isotherm to quench after waiting for main working procedure, get leaving martensite of body of shellfish family name, temper and the compound organization of a few leftover austenite, can obtain what fine eager to do well in everything spends He Ren sex to match, its obdurability is apparent the heat treatment method of prep above convention. Apply at two kinds of patterns that my company uses, its durability rises apparently. Keyword: High temperature moves qualitative, isotherm to quench, compound organization, obdurability is had after heat treatment of classics of introductive Cr12MoV steel wearability and tall hardness, intensity, good temper by dipping in water show performance and be applied extensively at cold make a pattern. The mould rolling silk that we abstain (1) seeing a picture and abnormity punch (use material of two kinds of moulds all is 2) seeing a picture Cr12MoV steel. After be being handled with method of groovy heat treatment, mould rolling silk ages in use process ministry collapse ages and discard as useless, every pairs of mould machines a spare parts on average to make an appointment with 1560. Abnormity punch is machining a spare parts 500 when, occurrence brittleness of pointed horn place drops a phenomenon, after although be repaired via a few,be being ground, average treatment spare parts is 3000 or so only. This affected every months of production amount of hundred thousands of spare parts and plan badly undoubtedly. Accordingly, solve and raising durability of two kinds of moulds is the task of a research that is placed before us. Of 1 mould enlist in army condition and invalidation analysis 1.

1 enlist in army the condition rolls filar mould is to rolling cold conditions of the treatment on filar machine tool of 35 steel spare parts outside whorl, precision of spare parts whorl amounts to 6 class, when the whorl outside machining a spare parts because extruding deflection is bigger, ask this mould is had taller fight be out of shape ability, wearability and tenacity. Abnormity punch is on 100T punching machine the duralumin spare parts of extruding anneal condition shapes, deflection of spare parts plasticity is bigger, and the spare parts shapes hind the machining of the foreword after undertaking no longer, consistency of size of place of requirement mould work is good, should have sex of He Ren of higher compression intensity, wearability. 1.

2 invalidation form and analyse us to undertake to the one by one of two kinds of moulds that already discarded as useless hardness detects, all be 60 ～ 62HRC, accord with blueprint requirement, organization of examination of metallographic of classics of sampling stripping and slicing is temper martensite + a few remain austenite + carbide, carbide slants analyse level is 3.

5 ～ 4.

5 class differ. Outside when when because produce grinding crackle,two kinds of moulds divide a few moulds rolling silk, be being used, expand along former crackle again and discarding as useless, the common characteristic of form of invalidation of the others mould all ages for brittleness collapse or drop piece, the working place extruding that because intensity and hardness are not worth generation,did not discover is out of shape or wear away. Fall hardness of two kinds of moulds to 58 ～ 60HRC when, brittleness collapse ages or drop a phenomenon to do not have improvement, can see from this: Big, tenacity is not worth brittleness of mould work place is to cause the main reason with mould small durability, assuring what mould fine eager to do well in everything spends He Ren sex to match is the main measure that raises mould durability. The 2 ways that raise mould obdurability 2.

1 improvement carbide slants analyse, reduce steel of carbide grain Cr12MoV to belong to steel of mould of alloy of tall carbon tall chromium, the organization is in-house in all brilliant carbide much, grain is big, slant analyse is serious, the existence of these carbide, except cause a mould easily to quench craze is mixed outside be out of shape, still increased a mould to use the brittleness in the process, reduced tenacity. Accordingly we use groovy method to undertake for many times to this steel mound is thick and unplug long, carbide of will big lump is attacked broken, improved constituent interior carbide to slant analyse, forging to the crackle that the process appears expands and discard as useless to prevent the blemish such as the crackle that exists as a result of raw material surface to bring about, the method that machining uses before forginging purify of semifinished product surface 2 ～ 3mm, undertake the ball changes anneal in time after forging, <250HBS of the hardness after anneal, the ball changes level to be 2 ～ 3 class. 2.

2 increase high temperature to because Cr12MoV steel organizes in-house carbide to hand in edge configuration to submit pointed horn form,move simple working procedure, cause the stress concentration that pointed horn is in extremely easily, increased to quench crackle of craze, grinding and the liability that brittleness produces in use process. When moving qualitative craft parameter with convention, because quench,heat temperature is low, unalterable the pointed part pattern with deliquescent carbide, its action and meaning are not very big. Mix to mould grinding crackle to reduce carbide grain and pointed part pattern further the influence of brittleness, according to the characteristic of character of Cr12MoV steel material and heat treatment craft, after mould rough machining, the high temperature that raises semi-manufactured goods moves simple working procedure, be about to quench heat 2 curing temperature that temperature raises this material, high temperature temper has after quenching (3) seeing a picture. Rise quench heat temperature can make heating inferiorly formerly the lesser carbide that cannot dissolve below temperature dissolves further, although a few bigger carbide cannot dissolve but also can heat in higher temperature when, because pointed horn is in high concentration carbon,be in to the plane that is close to carbon of place low density with its (or the position with curvature large radius) diffuse aggravate, produce pointed horn to handle the small dissolve appearance of carbide, make pointed part part produces passivation, curvature radius increases. This kind is opposite of small lump carbide dissolve and chunk shape carbide is pointed the change of horny pattern, alleviate and reduced carbide amount to be mixed more when pattern of the part that show a needle easy the adverse effect that causes stress concentration, and already a large number of carbide of dissolve are in process of high temperature temper with petty graininess carbide even ground separate out, the brittleness that reduced a mould not only, increased tenacity, issued strength of body of shellfish family name to lay a foundation to when subsequently isotherm quenchs, rise again. Accordingly, cr12MoV steel increases attune of semi-manufactured goods high temperature to pledge working procedure is to raise mould obdurability and one of important step that reduce grinding crackle. 2.

3 use Yawenjia hot, isotherm quenchs Cr12MoV steel is in 1020 ～ 1040 ℃ heat quench after heat preservation, can obtain quench martensite measures most, hardness to reach highest value. According to mould invalidation form, make sure for utmost ground the mould is below the premise that has enough strength and hardness, rise further and dig material tenacity latent capacity, used reduce heat temperature, extend heat preservation time, undertake isotherm quenchs leaving put oneself in another's position of shellfish family name, it is next under Ms line temperature temper two technique (4) seeing a picture. Outside because the grown rate of austenite grain is divided,be being concerned with heat preservation time, mainer depend on austenite changes heat temperature. Use Yawenjia heat extends heat preservation time, its purpose is to get even and petty austenite grain as far as possible, ask when it is certain to make alloy carbide is in inside most dissolve at austenite in the center, because organize the transmissibility of change, the grain that compound organization gets when quenching all heats than convention many temperature is small, raised the tenacity of material. Using the end that isotherm quenchs is to obtain a certain quantity of family name issueing shellfish to body is organized and cool subsequently leftover austenite continues to transform so that organize to martensite in the process. Because Cr12MoV steel contains carbon the volume is high, the organization of body of family name issueing shellfish that gets tall carbon is divided outside having good strength, martensite of temper of apparent prep above organizes its fracture toughness, after and body of instantly shellfish family name is mixed martensite is combined by certain proportion, the move since the system of family name issueing shellfish that begins to form breaks up the action of austenite grain, make the martensite that forms subsequently is refined again, dropped brittleness transition temperature consequently, be helpful for intensity rise. Because this uses Yawenjia,heat and isotherm quench the matching that makes the mould obtained good strength and tenacity. 2.

4 increase the process of effectiveness for a given period of time that eliminates stress to roll filar mould tooth model after heat treatment essence of life grinds treatment to shape, abnormity punch undertakes line cut treatment shape after semi-manufactured goods heat treatment. In rolling filar mould to be machined in grinding, because grinding overheat causes grinding stress,produce grinding crackle or the brittleness in increasing use process easily. Online cut machines abnormity punch in the process, because the surface cools quickly after instantaneous high temperature melts when, arose to quench newly again organization, stress of its surface layer is caused easily brittleness arises in use process or crackle arises in had deposited Cheng, especially performance of position of mould pointed horn is highlighted particularly. The stress that forms to eliminate the mould after machinery or report are machined and the effect that produce brittleness in use process, after mould grinding or line cut are machined, raised low temperature (180 ℃ of 160 ℃ ～ ) heat, 12 ～ the elimination of 16 hours of heat preservation stress ageing treatment. High temperature of classics of mould of steeliness of Cr12MoV of 3 application result moves the compound organization that pledge and gets, in make sure mould work place is fought be out of shape on the foundation of ability and wearability, raised tenacity significantly, those who got obdurability is organic cooperate, increase after eliminating process of stress effectiveness for a given period of time, farther need produces the effect of brittleness in use process besides the mould. This method applies in production, the experiment rolls silk 10 pairs the mould machines a spare parts every pairs on average 12300, abnormity punch machines a spare parts every on average 24000, durability raised 8 times above than former method respectively, satisfied the requirement that produces amount and plan, already brought into this method solidify the heat treatment procedure of two kinds of moulds. 4 epilogue 1) , by theoretical analysis and test result, the mould rolling silk of Cr12MoV steeliness and attune of high temperature of abnormity punch classics quench with isotherm character gotten compound organization, the temper martensite that its obdurability gets after heat treatment of convention of apparent prep above. 2) , when increasing high temperature to tone can alleviate character and reduce Cr12MoV steel carbide to show pointed part pattern easy the adverse effect that causes stress concentration. The 3) , stress that after increasing the benefit of working procedure of effectiveness for a given period of time that eliminates stress to be machined at eliminating grinding or report, forms, reduced a mould to use the brittleness of the process further. CNC Milling