Cast stainless steel
Investment casting process
Cast stainless steel refers to cast steel that can resist environmental corrosion.
Cast stainless steel can generally be divided into three categories, namely, medium and high-strength martensitic stainless steel for engineering structures, corrosion-resistant stainless steel and heat-resistant stainless steel.
Medium and high strength martensitic stainless steel
Including martensitic stainless steel and precipitation hardening stainless steel. In engineering applications, the main index is mechanical properties.
And it has good corrosion resistance in atmospheric media and milder corrosive media (such as water and certain organic substances). The metallographic structure is low-carbon lath martensite
Corrosion resistant stainless steel
Also known as stainless acid-resistant steel. The main assessment of its corrosion resistance can be divided into two categories: chromium stainless steel and nickel-chromium stainless steel.
The main factors affecting the corrosion resistance of stainless steel are the carbon content and the amount of precipitated carbides, so the carbon is generally very low, usually less than 0.08%.
Heat-resistant stainless steel
For heat-resistant stainless steel, the mechanical properties of high temperature depend on the stable carbide precipitation phase in the steel. The carbon content is higher than that of corrosion-resistant steel, about 0.20% or more.
The heat-resistant temperature of high-alloy heat-resistant steel castings can reach above 650℃
Stainless steel casting
Silica sol process stainless steel casting belongs to investment casting or precision casting. It is a casting process with little or no cutting, and is an excellent process technology in the foundry industry.
Stainless steel casting is not only suitable for casting of various types and alloys. Moreover, the dimensional accuracy and surface quality of the produced castings are higher than other casting methods.
Even complex, high-temperature resistant, and difficult-to-process castings that are difficult to cast by other casting methods can be cast by investment casting.
what is Investment casting process
It uses fusible materials (such as wax or plastic) to make a fusible model (referred to as investment or model). Coat several layers of special refractory paint on it. After drying and hardening to form an integral shell, steam or hot water is used to melt the model from the shell.
Then put the shell in the sand box, and fill it with dry sand around it. Finally, the casting mold is put into the baking furnace for high-temperature baking (if a high-strength mold is used, the mold shell after demolding can be directly fired without modeling). After the mold or shell is fired, molten metal is poured into it to obtain a casting.
Advantages of investment casting
Because investment castings have high dimensional accuracy and surface finish, machining work can be reduced. Just leave a little machining allowance on the parts with higher requirements.
Even some castings only leave a grinding and polishing allowance, and can be used without mechanical processing. It can be seen that the use of investment casting method can save a lot of machine tool equipment and processing man-hours, and greatly save metal raw materials.
Another advantage is that it can cast complex castings of various alloys, especially high-temperature alloy castings.
For example, the blade of a jet engine, its streamlined profile and cooling cavity, can hardly be formed by machining technology.
Production by investment casting process can not only achieve mass production, ensure the consistency of castings, but also avoid the stress concentration of residual knife marks after machining.
