Welding question

[Spook50]

A while back, Georg (orangefj45) posted a thread about welding transfar case gears together to make a fully splined input gear (this was for 60/62 series tcases). After welding, he wrapped the input gear in a welding blanket and left it overnight. I had always thought that quenching steel when it gets that hot would harden it better, so why wrapping and letting it slowly cool?

 

['74 UA FJ]

Distortion, brittleness. Air cooling is still "quenching" by the way.

 

['74 UA FJ]

I believe a preheat/weld/slow cool process is better for high strength, case hardened material.

 

[Spook50]

I believe a preheat/weld/slow cool process is better for high strength, case hardened material.

Interesting. So that would explain why it was a better route to take with the gears.

So is quenching still good when it comes to stuff like bracketry? That's what I did with my Mazda seat brackets.

 

['74 UA FJ]

Seat brackets? It really doesn't fxxxing matter.

 

[Spook50]

Seat brackets? It really doesn't fxxxing matter.

Groovy.

 

[fieldsken1]

Seat brackets? It really doesn't ****ing matter.

it might matter depending on how big ones ass is???????

 

[Pin_Head]

Gears are usually case hardened carbon alloy steel, like 8620 or maybe 1040 on older gears. Slow cooling is called normalizing and it prevents them from becoming brittle by rapid cooling. Welding case hardened steel presents an additional problem of the high carbon content of the case layer, when mixed with the weld filler can result in the formation of iron carbide or cementite, which is brittle and can crack easily. You can either grind off the case layer or anneal it with a torch to let the carbon fizz away.
Quenching and brittleness is not an issue with low carbon mild steel

 

[Spook50]

So would the iron carbide still form during normalizing?

Sent from a phone, and stuff

 

[calstyl2]

This is like the e9999 of welding.

 

[Pin_Head]

So would the iron carbide still form during normalizing?

Sent from a phone, and stuff

It depends on the amount of carbon and the rate of cooling. It isn't going to happen at the mormal concentrations of carbon alloy steel, but it is a potential problem with welding case hardened steel.

Martensite is also brittle, but it is a crystal structure of steel that is formed during rapid cooling, like water and oil quenching. Some steels quench rapidly in air, and are known as air hardening alloys.

I learned this in welding class and I stayed in a Holiday Inn Express. I also kept my welding text book.

 

['74 UA FJ]

So, basically, your Mazda seat brackets don't fxxxing matter. Thanks for the fxxxing question. Use fxxxing google next fxxxing time.

 

[Spook50]

So, basically, your Mazda seat brackets don't fxxxing matter. Thanks for the fxxxing question. Use fxxxing google next fxxxing time.

Save the ball busting for Chat. I'm not at all worried about the brackets I made. Just trying to learn why the different method when Georg welded tcase gears, and further educate myself on the difference between case hardened steel versus low carbon steel,

Sent from a phone, and stuff

 

[Spook50]

For some reason Forum Runner doesn't let me delete duplicate posts. Fantastic......

 

[rusty_tlc]

So, basically, your Mazda seat brackets don't fxxxing matter. Thanks for the fxxxing question. Use fxxxing google next fxxxing time.

......

 

[PAToyota]

So is quenching still good when it comes to stuff like bracketry? That's what I did with my Mazda seat brackets.

Rarely do you want to quench - as in quench in water - a weld. It is going to make the weld more brittle.

Many moons ago in a welding class the instructor did a demonstration. Welded up two 1/2" x 2" bars identically, but one was left to cool normally and the other immediately quenched in water after welding.

Put in a vise and hammered on, the quenched weld broke on about the third or fourth hit. The instructor pointed out the crystallization of the metal at the break. The one that cooled was bent to 90° with no sign of tearing.

 

[SM Racing]

I bury parts in a bucket of sand if I need to slow the cooling and keep it from being exposed to as much oxygen. It is better than air cooling and better than wrapping something in a welding blanket.

 

[Spook50]

Rarely do you want to quench - as in quench in water - a weld. It is going to make the weld more brittle.

Many moons ago in a welding class the instructor did a demonstration. Welded up two 1/2" x 2" bars identically, but one was left to cool normally and the other immediately quenched in water after welding.

Put in a vise and hammered on, the quenched weld broke on about the third or fourth hit. The instructor pointed out the crystallization of the metal at the break. The one that cooled was bent to 90° with no sign of tearing.

Damn, now I want to check my brackets to make sure I didn't severely weaken them by water quenching. Be ugly to have them fall apart in an accident.

SM, great idea. I'll do that next time I do another project like this.

Sent from a phone, and stuff

 

[SM Racing]

For most parts made of mild steel, do not quench them, let them air cool and use the proper filler metal. I would not have quench seat brackets. Those parts should deform is subjected to very high loading. If quenched they could break instead of bending.

 

[Spook50]

For most parts made of mild steel, do not quench them, let them air cool and use the proper filler metal. I would not have quench seat brackets. Those parts should deform is subjected to very high loading. If quenched they could break instead of bending.

Very true on the deforming, now that I think more about it. I'm going to pull them out and check them closely this weekend. If they're going to break I'd rather have it happen in a vise than in an accident. Then at least I could repair them and let them cool normally.

Sent from a phone, and stuff