Welding Metallurgy sounds about as exciting as Quantum Physics.
Would you like to learn all about body centered cubic, face centered cubic, and hexagonal closed packed crystalline structures?
Would you rather be kicked in the balls than to study this picture of balls?
The best welders I know don’t know a thing about microstructure of metals and you know what ?
They don't need to Know!!
Here is the one down and dirty thing you need to know in order to be a good welder, fabricator, and craftsman: Are you ready? Don’t miss this!
Did you hear what I said? I know it seems simple but honestly, if you understand this one thing, you will stand head and shoulders over 90 percent of the people you work with. Even the engineers and inspectors. I am serious here! I have worked with PhDs, and engineers for several years and I stand behind what I am saying here. Most of them are smart folks, but they are not welders and most of them just dont have a "hands on" feel for the affects of heat on metal.
Heat affects different metals in different ways but it’s really not all that complicated.
Welding produces enough heat to melt the metal so there will always be a heat affected zone next to the weld where the metal got really hot and then cooled pretty quick because of the relatively cool metal surrounding the weld. Think of heating up something red hot and then dunking it in a bucket of cold water. That’s what happens when you weld something. But it only happens in a narrow zone next to the weld.
Carbon steel, cast iron, low alloy steels like 4130 chromoly, and straight chromium stainless steel like 410 all harden from heating and then quick cooling.
Almost everything else does not harden from heating and quenching. If you don’t get this yet, read it again. And then again. And then again, And then again.
Learn more about Tig welding 4130 chromoly
The Photo on the left is a Normalized microstructure. The 4130 chromoly was heated and then allowed to cool very slowly. The photo on the right shows a totally different microstructure. A very hard and brittle one called martensite.
Almost everything else does not harden from heating and quenching
Have you got it?.
Its really important to understand before we move ahead in the rest of your Crash Course on Down and Dirty Welding Metallurgy.