Austenitic and Martensitic stainless steel

Welding austenitic and martensitic stainless steel

Although stainless steels have good weldability, this property can be achieved by modifying the content of carbon in their alloy. A lowered carbon content with inclusions of nitrogen improves the weldability of the 300 series stainless steel. Having a higher content of carbon in its alloy makes it difficult to weld martensitic grades. Therefore, during the welding of these alloy grades, it is necessary to conduct both a preheat as well as post-weld heat treatment.

Austenitic and martensitic stainless steel grades
Martensitic stainless steels are available based on their chemistry and are further classified into four categories. Grades with Fe-Cr-C Chemistry tend to be wear-resistant and are useful for engineering. Similar to the former are grades with Fe-Cr-Ni-C chemistry. These grades have some carbon content replaced with nickel and exhibit properties such as good casting properties, weldability, and resistance to cavitation erosion. Precipitation hardening grades exhibit properties like high strength and good toughness, whereas Creep-resisting Martensitic stainless grades are produced with trace quantities of elements like niobium, vanadium, boron, and cobalt. By adding these elements, there is an increase in the mechanical strength, with creep resistance up to a temperature of 650 °C. The austenitic class can further be segregated into two more categories i.e. 200 series and 300 series. While the 300 series are popular, the inclusion of nitrogen in the chemistry of the 200 series gives them an increase of approximately 50% yield strength in comparison to the 300 series.

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