Solidification Cracking 4

[xray1366]

Hi everyone.
My QC Manager wanted me to search for Solidification Cracking and find out when the Solidification Cracking takes place (when W/D < 0.7 or W/D < 1)? And what are the Parameters W and D?
Thank you for your help.

 

[metengr]

Learn to search the internet

http://content.lincolnelectric.com/pdfs/knowledge/articles/content/weldcracking.pdf

 

[xray1366]

I searched and found the answer before you reply, anyway thank you metengr.

 

[xray1366]

Sorry,
May I ask another question?
1) How long does the Solidification Cracking take to appear after the welding?
2) To what thickness the Solidification Cracking occures after PWHT?
Sorry for bad English grammer.
Thanks.

 

[Guest102023]

The term Solidification Cracking is self-descriptive: it occurs during weld solidification. In a situation where it is possible, my advice is 'don't be greedy'; i.e., back off on the weld parameters (esp. high amperage) that can cause it. Pay attention to joint design and minimize fit-up gaps.

 

[Duwe6]

And make sure to fill the "stop" crater after a brief pause in weld deposition.

 

[xray1366]

Thank you, and don't you have any idea about Solidification Cracking after PWHT? Does it take place after PWHT?
Thank you in advance.

 

[SJones]

That's 'reheat cracking'. Try doing a search for that phenomenon.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[xray1366]

How does the Solidification Cracking grow after Post-Weld Heat Treatment? May it grow after PWHT? Upto what thickness may it grow??
Thanks.

 

[metengr]

Don't mix up the term solidification cracking with reheat cracking. Solidification cracking occurs during welding, and has nothing to do with PWHT.

Reheat cracking only occurs during PWHT and can grow after PWHT based on tensile stresses in service. Normally, nondestructive testing is performed after welding or PWHT to avoid missing either types of defects.

 

[xray1366]

Thanks Metengr, I know about reheat cracking but I mean growing, not occuring. Do you mean that the Solidification Cracking doesn't grow after PWHT and PWHT has no effect on the Solidification Cracking?

 

[metengr]

Solidification cracks CAN grow after PWHT if service stresses in the weld region are high enough to induce growth. IF service stresses are low, I have seen solidification cracks remain for years with no growth or harm to the component.

PWHT has no effect on solidification cracking.

 

[xray1366]

I've seen a formula about reheat cracking:
ΔG =Cr+3.3Mo+8.1V
and it was mentioned if ΔG<0 then the suceptibility to this cracking is low!! while ΔG can not be less than zero!!!
I need to know what is the proper formula if there is.
Thank you.

 

[metengr]

You mean the reheat cracking susceptibility equation in the attached paper.....

http://www.vanitec.com/pdfs/f07b7c40c511457dfb5983f7572041bc.pdf

What is being mentioned is that when [delta]G[/delta] goes toward zero, susceptibility is reduced. The equation represents the heavy hitters that influence reheat or stress relief cracking. Yes, for carbon steels this can be zero - no chromium, no molybdenum and no vanadium!

 

[metengr]

You might also want to review the information below

http://www.theiiwmumbai.8m.com/defects7.htm