24 July 2021 Mould Steel Bar
Cr4W2MoV Mould Steel Bar
Cr4W2MoV steel is a kind of cold work die mould steel with relatively stable performance. The service life of its die is greatly improved compared with Cr12 and Cr12MoV steel. The main characteristics of Cr4W2MoV steel are that the eutectic carbide particles are fine, uniformly distributed, have high hardenability and hardenability, and have good wear resistance and dimensional stability. The steel has a narrow hot working temperature range and high deformation resistance. It has been proved by actual use that Cr4W2MoV steel is a cold work die steel with good performance, which can be used to manufacture various die, cold heading die, blanking die, cold extrusion die and wire-back plate and other tooling dies.
The higher chromium in Cr4w2Mov steel is to make the steel have higher hardenability, and a part of the chromium can also generate chromium compounds, which is beneficial to improve the wear resistance of the steel. W, Mo, and V are all conducive to improving thermal stability and secondary hardening. Their respective contents are determined in consideration of the following factors: adding too much w will increase the unevenness of carbides, and replacing W with Mo The distribution of carbides can be improved. Adding 1% vanadium can generate a part of Vc that has not been dissolved during quenching heating to improve wear resistance. However, adding too much vanadium will deteriorate the grinding performance of steel. The regulation of carbon content is to take into account that a sufficient amount of carbides can be generated to obtain high wear resistance, but not too much to deteriorate the properties of the steel (annealing hardness, toughness, etc.). Slightly increasing the silicon in the steel is to improve the tempering stability.
Cr4W2MoV steel is a kind of substitute steel developed for the shortcomings of Cr12 series steel. It has good wear resistance and secondary hardening ability. The eutectic carbide particles of the steel are fine, uniformly distributed, and have high hardenability and hardenability, as well as good wear resistance and dimensional stability. However, the hot working temperature range of steel is narrow, and the deformation resistance is greater. In order to obtain a hardness of ≤255HBW, the isothermal duration of the steel should not be less than 6-8h. Hardening depth: φ150mm×150mm, can be quenched internally and externally, with a hardness of 60HRC, and air quenching depth: 40~50mm. The performance of this steel is relatively stable, and the service life of its mold is greatly improved compared with Cr12 and Cr12MoV steel.
Cr4W2MoV steel has a narrow forging temperature range and is prone to overheating, overburning and forging cracks. It can be forged according to the method of Cr12 series steel. After the φ98mm quenched sample is air-cooled at 980°C, the core hardness reaches 58-60HRC, and the surface hardness reaches 63-67HRC. The toughness is best when quenched at 1020°C and tempered at 400°C; after tempering at 500~520°C for 1 to 3 times, it has better secondary hardenability, decreased toughness, and peak flexural strength , Compressive yield strength is about 10% higher than Cr12MoV steel. The quenching deformation trend of this steel is similar to that of Cr12 series steel, and it has better flexibility.
Chemical Composition:
| C(％) | Si(％) | Mn(％) | P(％) | S(％) | Cr(％) | Ni(％) | Mo(％) | V(%) | W(%) | Cu(%) |
|---|---|---|---|---|---|---|---|---|---|---|
| 1.12～1.25 | 0.40～0.70 | ≤0.40 | ≤0.030 | ≤0.030 | 3.50～4.00 | ≤0.20 | 0.80～1.20 | 0.80～1.10 | 1.90～2.60 | ≤0.30 |
Mechanical Propoerties:
| Yield Strength Rp0.2(MPa) | Tensile Strength Rm(MPa) | Impact Energy AKV(J) | Elongation at Fracture A(%) | Reduction in Cross Section on Fracture Z(%) | Impact toughness value αkv (J/cm2) | Hardness(Brinell) |
|---|---|---|---|---|---|---|
| ≥ 902(85) | ≥ 941(100) | ≥ 24 | ≥ 41 | ≥ 23 | ≥ 88 | ≤ 431 |
Heat treatment:
The mechanical properties of Cr4W2MoV steel when using the best heat treatment specifications are higher or close to those of Cr12MoV steel. The production practice has proved that the heat treatment process of this steel grade is simple, the deformation is very small, and it can be controlled by multiple tempering. The wear resistance exceeds Cr12MoV steel, and it is known as "high wear resistance cold work die steel".
The Cr4W2MoV steel grade has a narrow forging temperature range, so the temperature must be controlled during forging. If the initial forging temperature is too high, forging cracks of the shaft will occur. Practice has shown that when the forging temperature is lower than 850°C, the deformation resistance is very large, the plasticity is reduced, and cracks will appear. But as long as you have a good grasp of the key points of forging and the temperature, there is no difficulty in forging. If the forging method of Cr12 steel is mastered, the forging of Cr4W2MoV steel will not be a problem.