24 July 2021 Mould Steel Bar
9Mn2V Mould Steel Bar
9Mn2V is an excellent cold work die mould steel. 9Mn2V steel is with better comprehensive mechanical properties than carbon tool steels. It is the only economical steel type in alloy tool steels that does not contain Ni and Cr elements. It has been long in China. Application history, accumulated rich experience in use, it has high hardness and wear resistance. The deformation is small during quenching and the hardenability is good. Because the steel contains a certain amount of vanadium, the grains are refined and the overheating sensitivity of the steel is reduced. At the same time, the carbides are finer and evenly distributed.
Cold work die steel is a low-alloy tool with better comprehensive mechanical properties than carbon tool steel. It has high hardness and wear resistance, good hardenability, and small deformation during quenching. It is suitable for making small cold work molds, especially for making various precision measuring tools (such as templates, block gauges, gauges, etc.) that require small deformation and high wear resistance, as well as precision screw rods, grinding machine spindles, etc.
Chemical Composition:
| C(％) | Si(％) | Mn(％) | P(％) | S(％) | Cr(％) | Ni(％) | V(%) | Cu(%) |
|---|---|---|---|---|---|---|---|---|
| 0.85～0.95 | ≤0.40 | 1.70～2.00 | ≤0.030 | ≤0.030 | ≤0.25 | ≤0.20 | 0.10～0.25 | ≤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) |
|---|---|---|---|---|---|---|
| ≥ 928 | ≥ 962 | ≥ 43 | ≥ 12 | ≥ 55 | ≥ 44 | ≤ 343 |
Physical Properties:
| Temperature (°C) | Modulus of elasticity (GPa) | Mean coefficient of thermal expansion 10-6/(°C) between 20(°C) and | Thermal conductivity (W/m·°C) | Specific thermal capacity (J/kg·°C) | Specific electrical resistivity (Ω mm²/m) | Density (kg/dm³) | Poisson’s coefficient, ν |
|---|---|---|---|---|---|---|---|
| 12 | - | - | 0.41 | - | |||
| 281 | 168 | - | 32.3 | 333 | - | ||
| 693 | - | 21 | 21.2 | 422 | 211 |
Application:
9Mn2V steel is suitable for the manufacture of various precision measuring tools and templates. It is also used for die and cold press dies, engraving dies, blanking dies, etc. with relatively small dimensions that are generally required, and it can also be used as structural parts such as screw rods for machine tools. Cold work die steel, the hardenability of steel, the hardness of quenching and tempering, wear resistance and strength are all higher than that of Cr12. Used to manufacture various cold punching dies and tools with large cross-sections, complex shapes and heavy working conditions, such as punching dies, trimming dies, hemming dies, deep drawing dies for steel plates, circular saws, standard tools and gauges, Thread rolling die, etc.
Cryogenic treatment:
9mn2v steel undergoes cryogenic treatment, which can precipitate highly dispersed ultra-fine carbides from the quenched martensite, which can be transformed into carbides after subsequent low-temperature tempering at 200°C. The martensite that has not been cryogenically treated, after being fired at low temperatures, only a small amount of carbides are precipitated in some local areas. 9mn2v adopts low-temperature chemical heat treatment method, while maintaining the high hardness and high wear resistance of 9mn2v steel, ion nitriding, gas nitrocarburizing, and salt bath thiocyanurizing common low-temperature chemical heat treatment infiltration layer adhesion resistance. The three kinds of low temperature chemical heat treatment infiltration layers all have obvious impact resistance and adhesion, and the salt bath thiocyanate co-infiltration is the best. The service life of 9mn2v steel stainless steel utensil drawing die after gas nitrocarburizing treatment is more than 30,000 pieces, which is more than 10 times longer than that of similar die with conventional quenching and tempering treatment.
Hardened:
In order to increase the mold life to more than 800,000 mold times, the hardening method of quenching and low temperature tempering can be implemented on the pre-hardened steel. When quenching, preheat at 500-600℃ for 2-4 hours, and then keep it at 850-880℃ for a certain period of time (at least 2 hours), then put it in oil and cool to 50-100℃ and air cooling. The hardness can reach 50 after quenching. -52HRC, in order to prevent cracking, 200℃ low temperature tempering treatment should be carried out immediately. After tempering, the hardness can be maintained above 48HRC
Equivalent Grade:
| ISO | ASTM | UNS | EN | ISO | JIS | KS | EN | DIN |
|---|---|---|---|---|---|---|---|---|
| 90MnV2 | O2 | T31502 | 90MnV8 | 105WCr1 | SKS31 | STS31 | 107WCr5 | 105WCr6 |