Technical parameters of rusty steel valve castings:
Name: gate valve (composed of valve body, valve break and rocker)
Pressure: 1500 × 6894.76 Pa
Material: SAF2507
SAF2507 stainless steel has been widely used in more and more industrial fields. The high content of ferrite in this steel increases the brittleness, poor fluidity and coarse grain of the steel, resulting in a greater tendency of hot cracking. In addition, the increase of nitrogen content has a greater probability of causing pores in the casting. In the melting process of casting liquid steel, the addition of nitrogen depends on the addition of CrN or MNN master alloy to make n solid solution in the steel matrix, In other words, the higher the content of Cr and Mn in the steel, the higher the amount of N added. If the amount of N added exceeds the amount of solid solution n of Cr and Mn, n will become dispersed gas. In the liquid steel, a large number of pores will be formed after solidification of the casting. Therefore, this kind of steel brings great difficulties to the design of valve casting process and the melting of liquid steel.
Therefore, we have conducted special research on the production of large-diameter high-pressure valve body of super duplex stainless steel SAF2507. Through the research on casting process, melting process (AOD refining method is adopted at the same time), chemical composition welding repair process and heat treatment process, the above casting difficulties have been solved, and the super duplex stainless steel SAF2507 and ordinary duplex stainless steel valve castings and other casting products can be successfully produced in batch.