While welding is a cost-effective joining process, the heat input and local melting of the steel can result in significant changes in the microstructure. This can impact the material properties of the welded joint, especially strength, ductility/formability and corrosion resistance, compared to the non-welded parent material. Therefore, for stainless steels in particular it is important to pay careful attention to the correct selection of welding method, filler and post-weld treatments.
The key message provided by the guide is that stainless steels are not normally difficult to weld as long as the correct procedures are followed. However, the actual welding practices used might differ considerably depending on which grade of stainless steel is being welded.
The guide starts by explaining the concept of weldability and how the weldability of stainless steels differs from the weldability of carbon steels. This is because the microstructure in stainless steel weldments is to a great extent dependent on the chemical composition and the thermal history. This means that the metallurgical changes occurring during solidification often have a much stronger influence on the properties of stainless steel welds than in the case of unalloyed steels.
The guide then outlines the most important practical considerations when welding the following grade groups:
- Austenitic stainless steels
- Duplex stainless steels
- Ferritic stainless steels
- Martensitic stainless steels
- Precipitation hardening stainless steels