Surgical stainless steel of body piercing jewellery and body modification implants. 440 and 420 stainless steels, known also by the name "Cutlery Stainless Steel", are high carbon steels alloyed with chromium. They have very good corrosion resistance compared to other cutlery steels, but their corrosion resistance is inferior to 316 stainless. Biomedical cutting instruments are often made from 440 or 420 stainless due to its high hardness coupled with acceptable corrosion resistance. This type of stainless steel may be slightly magnetic. Surgical stainless steel Surgical stainless steel is a grade of stainless steel used in biomedical applications. The most common "surgical steels" are
SAE 304 stainless steel cracking above about 60 °C. It is considered resistant to pitting corrosion in water with up to about 400 mg/L chlorides at ambient temperatures, reducing to about 150 mg/L at 60 °C. 304 stainless steel is also very sensitive at room temperature to the thiosulfate anions released by the oxidation of pyrite (as encountered in acid mine drainage) and can undergo severe pitting corrosion problems when in close contact with pyrite- or sulfide-rich clay materials exposed to oxidation. For more severe corrosion conditions, when 304 stainless steel is too sensitive to pitting or crevice corrosion by chlorides or general corrosion