The Effect of Heat Treatment on the Microstructure and Properties of MIM 17-4PH Stainless Steel

 

Date：[2024/8/16]
 

Heat treatment has a significant impact on the microstructure and properties of MIM (Metal Injection Molding) 17-4PH stainless steel. The following is a detailed analysis of this impact:

1. Organizational influence
Sintered structure:

The microstructure of MIM 17-4PH stainless steel after sintering is mainly composed of Flat noodles martensite and massive ferrite.
Solution treatment:

After solution treatment at 1040 ℃, the matrix structure of the material will change, mainly due to the formation of quenched martensite. During the solid solution treatment process, the austenite phase decomposes unidirectionally, resulting in finer and more uniform precipitate phases, which helps improve the machinability and ductility of the material.
Timeliness processing:

During the aging process, some quenched martensite will transform into tempered martensite, and tempered martensite will gradually connect into large flakes from dispersed strips. Carbides will also aggregate and grow. At the same time, the second phase particles precipitate and disperse in the matrix, including age hardening phases such as ε - Cu, NbC, M23C6, etc. They enhance the hardness and strength of the material through precipitation strengthening.
2. Performance impact
Hardness:

The hardness of MIM 17-4PH stainless steel after sintering is relatively low, only 24HRC. But after solution treatment at 1040 ℃, the hardness increased to 29HRC, and after aging treatment at 480 ℃, the hardness can be increased to 38HRC1. This indicates that both solution treatment and aging treatment can effectively improve the hardness of materials.
Corrosion resistance:

After sintering, MIM 17-4PH stainless steel showed corrosion spots in the salt spray test after 12 hours, but after solution treatment at 1040 ℃, no corrosion spots appeared after 24 hours of salt spray corrosion, indicating that solution treatment significantly improved the material's corrosion resistance. However, although aging treatment directly after sintering (such as 480 ℃ aging) improved hardness, the salt spray corrosion resistance decreased, and corrosion spots appeared after 8 hours.
strength:

The strength level of 17-4PH stainless steel can be adjusted through changes in heat treatment processes to meet the needs of different applications4. After heat treatment, its compressive strength can reach up to 1100-1300MPa, mainly due to the strengthening of precipitation phases during martensitic transformation and aging treatment.
In summary, heat treatment has a significant impact on the microstructure and properties of MIM 17-4PH stainless steel. Through reasonable solid solution treatment and aging treatment processes, the hardness, corrosion resistance, and strength of materials can be significantly improved, thereby meeting the application needs of different fields.
As a leader in the field of Metal Injection Molding (MIM), Shenzhen Yujiaxin Tech. Co., Ltd. focuses on providing excellent metal component solutions for the medium to high demand market. Relying on advanced MIM technology, we are able to accurately process metal components with complex structures, high precision, and stable performance, which are widely used in high-end fields such as communication, medical, automotive, aerospace, etc. Yujia Xin adheres to the spirit of craftsmanship, continuously optimizes the process flow, and ensures that every product can meet the most stringent quality standards of customers. We are committed to becoming a trusted partner for our customers, jointly promoting industrial upgrading, and creating a new chapter in metal parts processing.