How to determine what type and grade of metal a welder works with? Artem Komarov explained that the best advice I can give is if you don’t know what it is, don’t try to weld it. This is especially true for critical parts, the failure of which can lead to injury or death.
When welding some metals using inappropriate welding procedures, defects in the base metal, weld, or both can occur.
When asked to weld an unknown material, how can you determine what it is? First, you must be able to narrow down the possibilities using a baseline estimate. Look at the surface of the material and determine how heavy it is. This should allow you to classify the material into broad categories such as carbon or low alloy iron, stainless steel, nickel alloy, or aluminum alloy. Evaluating the area where you will need to weld can also give you important clues. Is there evidence that the part was welded during original manufacturing? If so, this is a good indicator that the material is weldable. Is there evidence that attempts have been made to repair the weld in the past? If previous repairs were not successful, this is a red flag warning you to be completely sure of what you are working on before proceeding with a new repair.
If you are repairing any equipment, you can call the original manufacturer and ask what material was used. Some products are usually made from a specific material. A little research on the materials commonly used to make the item to be welded can help you narrow down your choices.
If you work in a machine shop, you should be able to get very detailed material information from the mechanics. If they were processing new material, the mechanic might know exactly what it is. They can give you some useful information about a material based on its processing characteristics. You should be able to judge the hardness of the steel based on the feed rate used in the machining process. The method of chip formation during machining also contains useful information. You should avoid welding steels with small chips as they are more likely to be unmachined and subject to hot cracking when welded.
A spark test on steel and cast iron can give you a general idea of how much carbon is in a material. Spot chemical testing can also determine if certain alloying elements are present.
Chemical analysis will provide the best information to help determine the grade of the material. In many cases, you can submit a chip being processed from a material for analysis. If processing chips are not available, if possible, remove a small piece of material for analysis — approximately 2.5 cm
The bottom line is that it’s important to spend some time and maybe some money getting a clear idea of what material you’ll be welding if you want to make a repair that’s safe and lasts a long time, Artem Komarov clarified.
