MIM 420 is a hardenable, martensitic stainless steel widely used in the MIM industry for applications where high hardness and wear resistance are required along with some corrosion resistance. These characteristics mean that the alloy is often used in the automotive sector and for the production of parts for firearms and power tool components as well as surgical instruments. Its popularity has been achieved in spite of the difficulties faced in controlling sintering in a relatively narrow process window.
Chemical specification
The chemical composition of MIM 420 after sintering is as follows. (Measured in % of weight).
| C % | Cr % | Ni % | M0 % | Nb % | Mn % | Si % | Fe % |
| 0.35 – 0.5 | 12 – 14 | ≤0.60 | ≤0.60 | 1-2 | ≤ 1 | ≤ 1 | Balance |
Typical properties
Properties can vary and can of course be adjusted to your application needs. It is however important to remember, that the properties are intercorrelated – demands on certain properties will offset values for other properties. If you e.g. have a need for higher hardness then it will influence elongation to a lower value. You have to be willing to forego other properties, if you have high demands in one area.
The challenge is to know what kind of properties are needed. Especially if it is the first times working with MIM. Many drawings are not designed with MIM in mind, but rather regular machining.
The best solution to this issue is to use our many years of design and production experience. Please consult our experts early in the process for further discussions and information regarding material selection and not least design possibilities. For some guidance however, here are the typical properties of finished sintered parts:
| Sintered | Heat treated | |
| Density [% of theoretical] | ≥7.55 g/cm³ | |
| Yield strength Rpo.2 [MPa] | ≥600 | |
| UTS Rm [MPa] | ≥750 | |
| Elongation [%] | ≥ 1 | |
| Hardness [HRC] | 35-40 HRC | 45-55 HRC |
Typical Microstructure