The most widely used of the martensitic stainless steels is Type 420. In the annealed state (ferritic structure), it does not perform well against atmospheric corrosion. This is because during the annealing operation, at a temperature of approximately 760 ºC, carbon and chromium combine to form chromium carbides, Cr23C6. Each molecule of chromium carbide contains, by weight, approximately 95% chromium. Considering the high carbon content and low chromium content of 420 stainless steel (approximately 0.35%C and 12.50% Cr), as all carbon precipitates as chromium carbide during annealing, this precipitation will remove approximately half of the available chromium from the solid solution. In this condition the material does not resist corrosion and cannot properly be considered as a stainless steel (since it does not have a minimum of 11% chromium in solid solution).
Some applications of stainless steels
Stainless steel type | Application |
| Austenitic(corrosion resistant) | equipment for chemical and petrochemical industryequipping for food and pharmaceutical industrycivil construction household goods and utensils |
| Ferritic(corrosion resistant, cheaper) | appliances (kitchens, refrigerators, etc.) refrigerated countersmonedsautolactic industrycovered |
| Martensitic(high hardness) | cutlerysurgical instruments such as scalpels and brake disc cutting knives |
Therefore, the stainless steel 420, is placed in service by the user, only after a tempering treatment. When tempered, carbon is part of the martensitic phase, not being found in the precipitated alloy as chromium carbide.
Hot Tags: 420 stainless steel, supplier, customized, wholesale, cheap, discount, price list, low price, in stock, free sampler
