3 examples of common alloys used in Metal Injection Moulding
31 Jan. 2017
AISI 316L is an austenitic stainless steel commonly used in corrosive environments for a large range of applications. AISI 316 is the second most commonly used austenitic grade after AISI 304, globally, however in MIM the 304L grade is not readily available, so AISI 316L is used in all applications where AISI 304L would otherwise be used.
The 316L subgrades vary greatly and different properties can be achieved, e.g. some grades are better for polishing, some for geometrical stability. The selection of grade for the final product is based on the requirements of the part.
AISI 17-4 PH is a martensitic precipitation-hardening stainless steel that provides a good combination of mechanical and corrosion resistance. It is commonly used in MIM, since the mechanical properties make it possible to design parts which retain good strength. The secondary hardening can to some degree be done in the sintering process by adjusting the parameters, given the right properties as sintered.
The material is on par with 304L in terms of corrosion resistance, and can be substituted in many applications where the mechanical properties are required.
AISI M2 is a molybdenum-tungsten high speed steel used in a wide variety of combinations, from cutting tools to high wear applications. M2 is generally hard to machine, making MIM technology ideally suited. It only needs final finishing or may be used as sintered. The hardness of the part can be adjusted in the sintering process, so in many cases the secondary heat treatment can be skipped. Hardness of up to 58 HRC has been achieved as sintered.
In terms of corrosion resistance, it is worse than the equivalent block material, since after sintering the material is virgin and has no oxide layer protecting the part. Handling and transport therefore need to be planned for any parts manufactured using the material.