The biphasic stainless steel 10Cr25Ni6Mo2N (also known as 825) and its heat treatment process 1050-1100℃ solid solution treatment, is widely used in the production and process of parts and components with special requirements in the field of aerospace, mechanical engineering and fasteners. It has high strength, good plasticity and corrosion resistance. Through chemical composition control, solid solution heat treatment and appropriate structure design, the properties required by different components and parts can be optimized.
This alloy is mainly used to manufacture aerospace fasteners, engines and other structural parts, but also used to manufacture chemical and petrochemical equipment and components and heat exchange components.
1. Chemical Composition
Table 1 Chemical Composition of 10Cr25Ni6Mo2N
Element Content (wt%)
C 0.07-0.13
Si ≤0.6
Mn ≤2.2
P ≤0.035
S ≤0.03
Cr 23.0-25.0
Ni 5.0-7.0
Mo 2.0-3.0
N 0.4-0.8
2. Heat Treatment
10Cr25Ni6Mo2N stainless steel is a type of precipitation hardening stainless steel. The heat treatment process is conducted in 1050-1100℃ solid solution temperature and air-cooling after treatment. The heat treatment process is mainly used to enhance the strength and plasticity of the steel.
The heating temperature in 1050-1100℃ solid solution temperature must be controlled precisely and the holding time must be appropriate. Overheating and too long holding time will result in the too strong precipitation hardening of the alloy and its performance will decrease.
The air cooling rate needs to be controlled properly, so that the cooling rate of the alloy is slow enough to achieve uniform composition in the organization. Otherwise, the precipitation of hardening agents in the alloy will be uneven, and its strength and plasticity will be compromised.
3. Microstructure
10Cr25Ni6Mo2N stainless steel has a hard martensite matrix, a small amount of fine lath structure, and a small amount of austenite in the matrix. The chromium and nickel content of the alloy is high, the grain is fine and uniform, the content of impurity elements is low, and the mechanical properties of the alloy are excellent.
The martensite after heat treatment has a high transformation temperature, so that the austenite formed in the matrix needs to be used as a heat treatment carrier. The heat treatment process also determines that the martensite can remain in the atmosphere for a long time without aging.
4. Mechanical Properties
Table 2 Mechanical Proprieties of 10Cr25Ni6Mo2N
Property Standard Value
Tensile Strength 880 MPa
Yield Strength ≥640 MPa
Elongation ≥12%
Hardness ≥320HV
The excellent mechanical properties of 10Cr25Ni6Mo2N stainless steel mainly shares to the precise control of chemical composition, solid solution heat treatment process and reasonable design of microstructure. Furthermore, its strength and plasticity are also determined by suitable heat treatment process, which can optimize its performance for specific applications.
5. Conclusion
10Cr25Ni6Mo2N stainless steel is a type of precipitation hardening stainless steel. It has high strength, good plasticity and excellent corrosion resistance. Through precise control of chemical composition and reasonable structure design, 1050-1100℃ solid solution heat treatment and air-cooling can optimize its performance. The alloy is mainly used in fasteners, engine components and other structural parts manufacturing and other industrial fields.
