Q: My work involves performing machine shop welds and repairing machinery and structures in the field. I almost never have the benefit of being told what type of metal I’m welding. Can you please provide some guidance on how I might determine what type and grade of metal I am working with?
A: The best advice I can give is if you don’t know what it is, don’t try to weld it. This especially applies to critical parts for which failure can cause injury or death.
Welding on some metals using welding procedures that are not appropriate can cause defects in the base metal, the weld, or both.
When you’re asked to weld an unidentified material, how can you determine what it is? First, you should be able to narrow down the possibilities using a basic evaluation. Look at the surface of the material and see how heavy it is. This should allow you to put the material into the broad categories, such as carbon or low-alloy ferrous material, stainless steel or nickel alloy, or aluminum alloy. Evaluating the area where you’ll need to make a weld can also provide you with important clues. Is there evidence that the part was welded during original manufacture? If so, that is a good indicator that…