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Heat sinks and hardening in heat affected zone

Posted: Sat Jun 22, 2019 9:42 am
by maximumcoolbeans
If 4130 steel in heat affected zones is harder and more brittle because of rapid cooling, would avoiding the use of heat sinks reduce the amount of hardening and embrittlement in the heat affected zone because of slower cooling?

I thought of this question after reading this little welding tips and tricks article: http://www.weldingtipsandtricks.com/wel ... lurgy.html

Re: Heat sinks and hardening in heat affected zone

Posted: Sat Jun 22, 2019 8:47 pm
by Poland308
There are lots of variables that come into play. Two of the biggest I think of is 1 thickness of base metal. This affects the size of the HAZ. 2nd would be weld fit up. IE is it a lap joint, a butt weld, is it beveled, is there a gap, is it multi pass or single pass.

Re: Heat sinks and hardening in heat affected zone

Posted: Sat Jun 22, 2019 9:30 pm
by tweake
i think jody covered a fair bit of this in one of the more recent podcasts.

afaik the brittleness is not caused by slow cooling, its the opposite. i recall a few tricks like pre heating or using a oven or blanket to keep it hot and slowly cool down.
however check out the pod cast because i probably have got something wrong.

Re: Heat sinks and hardening in heat affected zone

Posted: Sun Jun 23, 2019 12:57 am
by Oscar
Assuming you are not going to do PWHT, then you definitely do not want to use heat sinks to help cool down a 4130 weld. A heat sink on a 4130 welded part that is not going to be PWHT is asking for a disaster if the part is subject to stress.

Re: Heat sinks and hardening in heat affected zone

Posted: Sun Jun 23, 2019 7:13 am
by maximumcoolbeans
Oscar wrote:Assuming you are not going to do PWHT, then you definitely do not want to use heat sinks to help cool down a 4130 weld. A heat sink on a 4130 welded part that is not going to be PWHT is asking for a disaster if the part is subject to stress.
Is that because in the case where heat sinks are used, there is faster cooling resulting in more hardening of the heat-affected zone?