English
中文简体
Español
Optimizing Stainless Steel Casting Parts to improve their corrosion resistance and mechanical properties involves many aspects such as material selection, casting process optimization, post-processing technology and application scenario analysis. The following are specific optimization measures and technical paths:
Choose the right stainless steel material
Adjust the proportion of main elements
Increase chromium (Cr) content (18%-25%): Enhance the oxidation resistance and corrosion resistance of castings.
Increase nickel (Ni) content (8%-12%): Improve the material’s resistance to stress corrosion cracking and improve toughness.
Add key trace elements
Molybdenum (Mo): Significantly improves resistance to pitting and crevice corrosion, especially suitable for high chloride environments.
Nitrogen (N): Enhances mechanical strength and improves local corrosion resistance.
Titanium (Ti) or niobium (Nb): Prevents intergranular corrosion, especially after welding.
Choose steel type according to application scenario
Austenitic stainless steel (such as 304, 316): has good comprehensive properties and is suitable for most environments.
Duplex stainless steel (such as 2205): has both high strength and excellent corrosion resistance, suitable for chemical and marine environments.
Precipitation hardened stainless steel (such as 17-4PH): Excellent in high strength and corrosion resistance, can be used in aerospace and medical fields.
Optimize the casting process
Improve metal purity
Use vacuum melting or electroslag remelting processes to reduce gases and inclusions in materials and improve the density of castings.
Optimize the pouring system
Properly design pouring risers and exhaust channels to reduce defects such as pores and shrinkage cavities and improve casting quality.
Control cooling rate
By adjusting the mold material or cooling medium, we can avoid coarse or uneven grains inside the casting and improve the uniformity of the material.
Numerical simulation technology
Use computer simulation software (such as ProCAST) to predict the temperature field and stress distribution during the solidification process and optimize the design plan.
grain refinement
Grain refiners (such as rare earth elements) are added during the casting process to improve the microstructure of the casting, thereby improving the mechanical properties and corrosion resistance.
Improve heat treatment process
Solution treatment
Key points of process
The casting is heated to an appropriate temperature (1050℃-1150℃), maintained for a sufficient time and then cooled quickly to dissolve the carbides and restore the austenite structure.
Performance improvements
Eliminate intergranular corrosion and improve corrosion resistance.
Homogenizes microstructure, enhances toughness and tensile strength.
aging treatment
Scope of application
For precipitation-hardened stainless steel, aging treatment is performed to precipitate strengthening phases, thereby significantly increasing strength and hardness.
Typical temperature
The aging process at 450℃-550℃ can improve the mechanical properties while maintaining a certain toughness.
Surface treatment technology
Passivation treatment
principle
A stable chromium oxide passivation film is formed on the surface of the casting to improve corrosion resistance.
Process optimization
Use nitric acid, citric acid or other environmentally friendly passivation solutions under strictly controlled temperature and time conditions.
Plating or coating protection
Commonly used techniques
Electroplating nickel or chromium on the surface of the casting to enhance the corrosion resistance of the surface.
Use fluorinated coatings or ceramic coatings to handle extreme corrosive environments.
Things to note
The coating thickness should be uniform to avoid corrosion due to local weakness.
mechanical strengthening
shot peening
By spraying high-hardness particles, the surface residual stress state is improved, fatigue strength and pitting corrosion resistance are improved.
electropolishing
Improves surface finish and reduces surface cracks and microscopic defects, helping to reduce the possibility of localized corrosion.
Testing and Quality Control
non-destructive testing
Ultrasonic testing: identify internal defects in castings such as pores and cracks to ensure internal tightness.
X-ray inspection: Check for hidden defects in complex structural castings, especially suitable for high-precision parts.
Corrosion performance test
Salt spray test: simulates corrosion resistance in highly corrosive environments.
Electrochemical corrosion experiment: Determine the electrochemical performance parameters of castings (such as pitting corrosion resistance potential) to evaluate the corrosion resistance of the material.
Mechanical property testing
Tensile testing: Testing the tensile strength and ductility of castings.
Impact test: Especially for low temperature environments, to evaluate the toughness of castings.
Application and optimization design
Optimized for usage environment
Chemical industry: Use high-molybdenum austenitic stainless steel (such as 316L) to cope with high acid and alkali environments.
Marine field: Use duplex stainless steel to prevent pitting and crevice corrosion.
Food industry: Use low-carbon stainless steel (such as 304L) to reduce intergranular corrosion in the welding area.
Structural design improvements
Reduce stress concentration: Optimize the shape of the casting to avoid localized corrosion or cracks at sharp corners and transition areas.
Reduce wall thickness differences: Maintain uniform wall thickness and reduce the impact of thermal stress on corrosion resistance.
By scientifically selecting materials, improving casting processes, and strengthening heat treatment and surface treatment, the corrosion resistance and mechanical properties of stainless steel castings can be significantly improved. At the same time, optimization solutions should be tailored based on specific usage scenarios and performance requirements to achieve the best balance of cost-effectiveness and performance.
