Common Stainless Weld Defects
Understanding common defects when welding is the first step to preventing them. Welding stainless steel is not much different from that required in welding standard carbon steel, with a few exceptions. First, you must exercise more care and control with regard to heating and cooling stainless steel. Second, it’s important to properly match filler metals with the material being welded.
The most common welding imperfection for stainless steels is cracking. Even with austenitic stainless steels, the most readily welded of all stainless steels, has a risk of cracking. This is because austenitic steels lack ferrite, which dissolves harmful impurities that result in cracks. In order to prevent cracking in these metals, especially for fully austenitic structures, the choice of a filler containing ferrite is highly recommended.
Ferritic stainless steels on the other hand, may crack during the welding process due to excessive grain coarsening which leads to poor toughness in the heat affected zone. When welding thin sections, no special precautions are necessary. In thicker material or highly restrained joints however, using a low heat input can minimize the size of the grain-coarsened zone and minimize the sensitivity to cracking. Likewise, using an austenitic filler may help to produce a tougher weld metal.
Martensitic steels are very prone to cold cracking as a result of hydrogen, which is also experienced with low allow steels. The risk of cracking generally increases with the carbon content. The risk of cracking in martensitic stainless steels can be combated by utilizing a low hydrogen welding process such as TIG or MIG, or by using hydrogen controlled fillers. Furthermore, pre and post-weld treatments, especially for thicker sections and higher carbon materials, will help to toughen the structure, enable the hydrogen to diffuse from the weld metal, and reduce the risk of cracking.
Do you have any Stainless Steel welds you’d like to share? Share your creations, tips, and ideas on our Facebook page!