| Metallurgy is the study of metal. Welding Metallurgy is | | | | are only partially right. Only a few metals harden by |
| the study of how welding affects the microstructure | | | | heating and quick cooling. Most other metals react |
| of metal. | | | | totally differently. |
| Did you know that there are metallurgists who devote | | | | Carbon and low alloy Steels like 4130, tool steel, cast |
| their lives to only studying carbon steels? So what | | | | iron, and some 400 series stainless steels harden by |
| about all the other metals like Stainless steel, nickel | | | | quick cooling from a red hot temperature. |
| alloys, aluminum, magnesium, titanium, cobalt, and | | | | But most other stainless steels, nickel alloys, aluminum, |
| copper alloys? | | | | magnesium, titanium, cobalt, and copper alloys will |
| Metallurgy is such a deep and mysterious subject that | | | | actually soften and lose properties by heating up red |
| it takes a lifetime to completely understand carbon | | | | hot and quick cooling. |
| steels much less all the rest. | | | | So what does this mean to you the welder? |
| So if is such a deep subject, what chance does a | | | | If you are doing a weld on 4130 chromoly, you need to |
| welder have in understanding enough about metallurgy | | | | know not to speed cool the weld or it will harden. |
| in order to be a better welder. | | | | If you are welding 6061 t6 aluminum, you need to know |
| There is good news. And its not that I saved a bunch | | | | that the weld area will soften if it gets too hot for too |
| of money on my car insurance by switching to GEICO. | | | | long, and strength will be lost and never regained |
| The good news is that you dont have to understand | | | | unless a full heat treatment can be done. |
| everything about metallurgy. You just need to | | | | Welding 301 full hard stainless steel is easy to do, but |
| understand some basic principles. | | | | heat from welding recrystallizes the work hardened |
| The absolute fundamental thing to understand is that | | | | microstructure and the strength and hardness goes |
| heat from welding affects metal. That sounds really | | | | right out the window. |
| simple but it is profound. Why? Because heat affects | | | | Welding 304 stainless can cause carbon and |
| different metals in different ways. | | | | chromium to bind up and form chromium carbides if |
| When you heat a piece of metal to red hot, and then | | | | the weld area stays too hot for too long. |
| quench it by dunking it in a bucket of cold water, what | | | | So do you get the picture. Heat affects different |
| do you think happens? If you answer "it hardens" you | | | | metals in different ways. |