AM 355 (Also known as PYROMET 355) is a chromium nickel molybdenum stainless steel. This alloy is a heat treatable austenitic / martensitic alloy (depending on the heat treatment). It offers high strength at moderately elevated temperatures and its corrosion resistance is superior to other quench-hardenable martensitic stainless steels. Higher strengths can also be obtained through cold working processes. This product is typically used for parts requiring oxidation resistance and high strength up to 800 F (427 C) and where such parts may require welding during fabrication. The material is well-suited for a wide range of applications. It is often used in structural applications, marine environments, and chemical processing plants. (UNS S35500)
