Scope of Application

Cold Work Tool SteelThe steel's hardenability, hardness after quenching and tempering, wear resistance, and strength are all higher than Cr12. It is used to manufacture various cold stamping dies and tools with larger cross-sections, complex shapes, and heavy working conditions, such as punching dies, trimming dies, rolling dies, deep drawing dies for steel plates, circular saws, standard tools and gauges, thread rolling dies, etc.

Electric FurnaceVacuum RefiningProduction, ForgingBlooming,Eutectic CarbidesUniform,High Hardenability, high wear resistance, high toughness, small volume deformation during quenching; therefore, its market usage is very large.

① Reduce the content of Cr,Mo, V elements, directlyReduce costs, but also severely affectPerformance, such as using Cr8, Cr12 to replace Cr12MoV;

② Change itsProduction Method, usingIntermediate Frequency Furnaceto replace electric furnace refining, resulting in excessive impurities in composition, using continuous casting method instead of spheroidizing annealing, reducingRolling Ratio, and many other methods to reduce costs, ultimately leading to materials not meeting expected effects during customer use,Mold Lifeis reduced, which can directly lead to cracking and scrapping.

Mechanical Properties:

Hardness: Annealed, 255～207HB (14-25HRC),IndentationDiameter 3.8～4.2mm; Quenching, ≥60HRC

Cr12MoV Applications

Cr12MoV Tool SteelHardenability, hardness, strength, and toughness after quenching and tempering are higher than CR12, workpieces with a diameter of 300~400mm can be fully hardened, with small quenching deformation, butHigh Temperature Plasticityis relatively poor. Cr12MoV is mostly used for manufacturing large cross-section, complex shape,Heavy Workloadcombined molds and tools. Such as punching dies, trimming dies, rolling dies, steel plates, etc.

Heat Treatment Specifications

Heat Treatment Specifications: 1. Quenching, 950～1000℃ oil cooling; 2. Quenching at 1020℃, tempering at 200℃ for 2 hours.

Metallographic Structure: FineGranular Pearlite+Carbides.

Delivery Condition: Steel is delivered inAnnealed Condition.

Cold ExtrusionMoldBlankingSoftening Specifications

UsingIron Chipsfor protective heating, temperature 760~780°C, time 10h, furnace cooling, hardness 196HBW, can smoothly achieve cold extrusion forming.

OrdinaryIsothermal spheroidizing annealingSpecification

850 ~870℃×3~4h, cool in the furnace to 740~760℃×4~5h isothermal, out of the furnaceAir cooling Hardness ≤241HBW,Eutectic CarbidesGrade ≤3

Optimal isothermal temperature 740~760°C, time ≥4 ~5h

Spheroidizing annealing specification

(860±1ü)°C×2~4h, cool in the furnace at a rate of 30°C/h, (740±10)°C x4-6h, slow cooling in the furnace to 500 ~600°C, out of the furnace for air cooling. Hardness 207 ~255HBW.

Deep cryogenic treatment

Crl2MoV steel undergoes deep cryogenic treatment, deep cryogenic treatment can make quenchingMartensitePrecipitate highly dispersed ultrafine carbides, followed by 200℃Low-temperature temperingAfterwards, these ultrafine carbides can transform into carbides. Martensite that has not undergone deep cryogenic treatment only precipitates a small amount of carbides in certain localized areas after low-temperature tempering. Crl2MoV adopts low-temperatureChemical heat treatmentMethod, based on maintaining high hardness and high wear resistance of Crl2MoV steel,Ion nitriding,Gas nitriding and carbon co-diffusion,Salt bathThe commonly used low-temperature chemical heat treatment diffusion layers have adhesive resistance. The three types of low-temperature chemical heat treatment diffusion layers all have significant impact resistance and adhesion, among which the salt bath thiocyanate co-diffusion is the best. Crl2MoV steelStainless steelThe service life of the gas nitriding and carbon co-diffusion treated stretching mold reaches over 30,000 pieces, which is more than 10 times the life of similar molds treated with conventional quenching,Tempering treatment.

Hardening treatment

To increase the mold life to over 800,000 mold cycles, pre-hardened steel can be subjected to quenching and low-temperature tempering hardening methods. During quenching, preheat at 500-600℃ for 2-4 hours, then hold at 850-880℃ for a certain time (at least 2 hours), cool in oil to 50-100℃ and air cool. The hardness after quenching can reach 50-52HRC, and to prevent cracking, low-temperature tempering at 200℃ should be carried out immediately. After tempering, the hardness can be maintained above 48HRC.Salt bath vanadium diffusionTreatment

Crl2MoV cold work mold steelNeutral salt bath vanadium diffusion treatment process, Crl2MoV steel can obtain carbide diffusion layers through neutral salt bath vanadium diffusion treatment. 1. Carbon vanadium compounds, the diffusion layer structure is uniform, with good

ContinuityAnd density, uniform thickness, dense structure, and very highMicrohardnessAnd high wear resistance,Surface hardness, wear resistance and anti-adhesion properties are significantly improved. 2.VCInAusteniteTheSolubilityIs higher than its solubility inFerrite, as the temperature decreases, VC precipitates from the ferrite, makingAlloy strengtheningAndGrain refinement, the compound layer exhibits high hardness. Cr12MoV belongs to high carbon high chromium ledeburite steel, with a high carbide content, about 20%, and often presents a banded or networked uneven distribution,SegregationSevere, and conventional heat treatment is often difficult to change the segregation of carbides, which severely affects the mechanical properties of the steel and the service life of the mold. The shape and size of the carbides also have a significant impact on the properties of the steel, especially large angular carbides have a significant cutting effect on the steel matrix, often becomingFatigue fractureSource, therefore, it is necessary to forge the raw material rolled steel, fully crush the eutectic carbides, making them small and evenly distributed,Fiber structureSurrounding the cavity or distributed in a non-directional manner, thereby improving the transverse mechanical properties of the steel.During forging,Steel ingot纤维组织围绕型腔或无定向分布, 从而改善钢材的横向力学性能。

锻造时对钢坯Perform multiple forging and drawing from different directions, and use the "two light and one heavy" method for forging, that is, lightly strike the blank during the initial forging to prevent fracture, and heavy strikes can be applied at intermediate temperatures of 980 to 1,020 °C to ensure the fragmentation of carbides.

Cr12MoV steel is not forged, and a solid solution double refinement treatment is used, that is, two-stage preheating at around 500 °C and 800 °C, followed by 1,100 to 1,150 °C.Solid solution treatment, quenching in hot oil orIsothermal quenching, 750 °CHigh-temperature temperingFatigue fractureMachiningAfter heating oil cooling at 960 °C, final heat treatment is performed, which can also refine carbides and round off edges, and refine grains.

Tempering specifications

Recommended tempering specifications for Cr12MoV steel

Cr12MoV quenching plan

Note: 1. Plan II and III are used for workpieces that require very highMechanical Propertiesand small deformation, such as threaded rollers,Wire drawing plates, complex shapes subjected toImpact loadmolds, etc.;

2. Plans IV and V are used for workpieces that requireRed hardnessand wear resistance, but with poor mechanical properties and large dimensional deformation, such as hotpunches working below 450 °Cetc.;

3. This steel is very sensitive to decarburization, and the preheating and heating used must be sufficiently deoxidized before use; if heated in a normalSalt bathenvironment, the workpiece can be placed inside a boxElectric Furnacefilled with

Carburizing agentorpig ironpowder (at this time, the workpiece may have slight carbon increase, and hardness can be increased by HRC 1~2).Table 2-3-1 Proportion of microstructure in quenching state

Quenching plan

Quenching specifications

Ordinary quenching and tempering specifications:

Quenching temperature1000~1050℃, quenching oil or gas, hardness ≥ 60HRC; tempering temperature 160~180℃, tempering time 2h, or tempering temperature 325~375℃, tempering times 3 times.

Typical examples

1. This steel can be used to make materials with a thickness >3mmPunchingMolds with complex shapesPunch, die, insert. It is recommended to have a hardness of 58~62HRC when making punches, and a hardness of 60~64HRC when making dies.

2. Used to make punches and dies that require high wear resistance in punching molds. It is recommended to have a hardness of 60~62HRC when making punches.HRCWhen making dies, it is recommended to have a hardness of 62~64HRC.

3. Used to makeDeep drawing moldsthat require resistance to pulling, recommended hardness is 62~64HRC.

4. Used to makeBending moldsthat require wear resistance and complex shapes for punches, dies, and inserts. It is recommended to have a hardness of 60~64HRC when making punches, and a hardness of 60~64HRC when making dies.

5. Used to make aluminum partsCold Extrusionpunches and dies. It is recommended to have a hardness of 60~62HRC when making punches, and a hardness of 62-64HRC when making dies.

Inspection methods for Cr12MoV:

① Detection of the elemental content of its coreComposition testing;

② Wear resistancePerformance testing,CarbidesLevel measurement, national standard requirement for hardness less than HRC60 after quenching;