3. Heat treatment after welding

3.1 Martensitic steels

When martensitic stainless steels are welded, austenite is formed, followed by martensite in the heat-affected zone. The higher the carbon content, the more brittle the martensite. For grades with a carbon content in excess of 0.15 to 0.2% by mass, the brittleness of the martensite is such that cracking may be delayed in the ZAT below 400°C (martensitic cracking). It is therefore recommended not to weld such grades (groups 2 and 3 (§ 1.1