Metallurgy is the discipline of metal. Welding Metallurgy is the discipline of how welding influences the micro-structure of metal. Were you aware that there are metallurgists who commit their lives to only studying carbon steels? So what about all of the other metals like Stainless steel, nickel alloys, aluminium, magnesium, titanium, cobalt, and copper alloys?
Metallurgy is a deep and puzzling subject it takes a lifetime to totally comprehend carbon steels a lot less all of the rest. So if is a deep subject, what chance does a welder have in understanding enough about metallurgy so as to be a better welder.
Some types of carbon steels are C45 Medium Carbon Steel grade, AISI 1020 Steel Low Tensile Carbon Steel, AISI 1045 Medium Tensile Carbon Steel Standard Specifications and ASTM A106 Grade B Carbon Steel Pipe’s Thermal Fluid Dynamics.
The pleasant news is that you do not have to appreciate everything about metallurgy. You simply need to grasp some guiding principles. The convincing basic thing to realize is that heat from welding influences metal.
Why? Because heat influences different metals in other ways. When you heat a chunk of metal to red hot, and then slake it by dunking it in a bucket of cold water, what do you actually think occurs? If you reply “it toughens” you are only partly right. Some metals toughen by heating and fast cooling. Most other metals behave fully differently.
Carbon and low amalgamate Steels like 4130, tool steel, forged iron, and some four hundred series immaculate steels toughen by fast cooling from a red hot temperature. But most other immaculate steels, nickel alloys, aluminium, magnesium, titanium, cobalt, and copper alloys will really melt and lose properties by heating red hot and fast cooling.
So what does this mean to the welder?
If you’re doing a weld on 4130 chromoly, you have got to know not to hurry chill the weld or it’ll toughen.
If you’re welding 6061 t6 aluminium, you must know the weld area will melt if it becomes too hot for too much time, and strength will be lost and never regained unless a full heat treatment can be done.
Welding 301 full hard stainless-steel is simple to do, but heat from welding recrystallizes the work toughened micro-structure and the strength and toughness goes right out of the window. Welding 304 stainless could cause carbon and chromium to bind up and form chromium carbides if the weld area stays too hot for too much time.