The few people that would say that chemistry is part of welding "steel" (what type of steel? what type of metal? how about aluminium? etc) includes welders.

eg: https://youtu.be/nfNvuTMDXNg?t=1420

In which a good machinist from Queensland, Australia discovers a crack and states he'll have to get the metal tested before he can repair the crack.

You know, to match the chemical composition, expansion rates, etc.