Application of Powder Metallurgical Stainless Steel Products in Seals

Powder metallurgy stainless steel seals are widely used in gas joint accessories, high-pressure water pump and gun accessories, automotive wiper accessories, pipe joint valve accessories, and so on. These powder metallurgy stainless steel parts have a common characteristic of excellent rust prevention and sealing performance. Capable of withstanding the ravages of eight kilograms of air pressure and 300 kilograms of water pressure.

The manufacturing process of powder metallurgy stainless steel seals:

Firstly, it is necessary to determine the production process of powder metallurgy stainless steel seals: mold design and raw material determination - mold manufacturing - raw material mixing - mold installation and machine debugging production - stainless steel materials to be vacuum furnace sintered - machining - deburring - rust prevention and oil immersion - inspection and qualified packaging.

Powder metallurgy stainless steel sealing material generally uses stainless steel SS316L or SS304L. In order to reduce pores, 2% to 8% copper based alloy is added to 304 or 316 stainless steel powder. Due to the low melting point of copper, liquid phase begins to form at 960 ℃, and all forms at 1000 ℃. When the temperature is higher than the melting point of copper, the flow of the liquid phase causes surface pores to continuously spheroidize and shrink; Due to the good wettability of copper on the stainless steel substrate, it can be evenly distributed on the stainless steel substrate, significantly reducing the porosity of the sintered body and improving its sealing performance.

The design process of powder metallurgy stainless steel seals is different from that of iron materials. Firstly, the molds cannot be interchangeable. The sintering expansion and contraction rate of iron based materials is usually around 3 ‰, while the sintering shrinkage of powder metallurgy stainless steel materials can reach about 15 ‰, which is quite different. Moreover, the precision of finished products made of powder metallurgy stainless steel is not easy to control due to its high shrinkage rate. Sintered billets have sufficient toughness and are easy to stick to the cutting tool, resulting in poor plasticity during secondary re pressing. Therefore, the production of powder metallurgy stainless steel has certain precision limitations. It's not a problem if it can be processed appropriately, but for those that cannot be processed (such as certain irregular parts), the accuracy must be within a controllable range before powder metallurgy can be used.

Powder metallurgy stainless steel seals require an intermittent vacuum sintering furnace with a temperature of around 1250 degrees Celsius. After degreasing, heating, high-temperature sintering, cooling, and sintering, it takes at least 12 hours even if cooled by cooling gas. Vacuum sintering requires a relatively high vacuum degree, and requires a sufficient furnace of products to reduce the amount. When cooling with nitrogen gas, avoid excessive temperature, otherwise it is easy to nitride stainless steel products. After gold processing, powder metallurgy stainless steel products are directly deburred and packaged for inspection.