Precipitation hardening stainless steel investment castings have important applications in modern industry. To understand its working principle, you need to first understand the characteristics of precipitation hardening stainless steel.
Precipitation hardening stainless steel is a special type of steel that precipitates fine strengthening phases in the stainless steel matrix through a specific heat treatment process, thereby significantly improving the strength and hardness of the material. This strengthening mechanism is based on the precipitation strengthening principle in metallurgy.
In the investment casting process, a wax mold is first made, and the shape of the wax mold is exactly the same as the required casting. Then, multiple layers of refractory materials are coated on the surface of the wax mold to form a shell. The role of the shell is to contain the molten metal during the subsequent pouring process and give the casting its final shape.
When the shell is prepared, the wax mold is melted and flowed out to obtain a cavity with a precise internal shape. This is the dewaxing process. Next, the stainless steel molten metal heated to a certain temperature is poured into the cavity. The molten metal cools and solidifies in the shell to form the required casting blank.
However, although the casting at this time has a basic shape, it has not yet reached the final performance requirements. This requires subsequent heat treatment. For precipitation-hardened stainless steel investment castings, the heat treatment process is particularly critical. Generally, the casting is first heated to a higher temperature for solution treatment to fully dissolve the alloying elements in the matrix, and then rapidly cooled to obtain a supersaturated solid solution structure.
Finally, aging treatment is performed. At the aging temperature, the alloying elements in the supersaturated solid solution will gradually precipitate in the form of fine particles. These precipitated fine strengthening phases are distributed at the matrix grain boundaries and within the grains, hindering dislocation movement, thereby improving the strength and hardness of the casting. Through this precipitation hardening method, precipitation-hardened stainless steel investment castings can meet the use requirements under harsh working conditions such as high temperature and high stress.
