HAZ of AHSS and Yield Strength

[jmarkus]

I've seen data out there on the effect of softening of the HAZ in a welded joint on tensile strength (and from what I remember hardness is a good indication of tensile strength - so that makes sense). Is there some information on the decrease (?) in yield strength of a HAZ in a welded joint in Dual Phase, HSLA and/or Martensitic steels?

Thanks,
Jeff

 

[GRoberts]

http://www.norlas.com/vis.asp?fileid=573

http://files.aws.org/wj/2006/08/wj0806-31.pdf

I know the AWS Welding Journal also had an article within the last year on this, but can't find it on-line at the moment.

You are correct that hardness and tensile strength have a direct relationship.

The hardness of the HAZ is mainly dependant on the chemical analysis of the base metal and the cooling rate.

On steels that gain a lot of strength based on mechanical or complex thermal treatments such as precipitation hardening, it tends to be softer than the base metal. On steels that gain thier strength based on transformation mechanisms, the HAZ tends to be harder than the base metal since it generally cools quicker than the original heat treatment of the material and is not always given a tempering thermal treatment afterwards as the base metal often is.

 

[TVP]

There is a lot of information on high strength steels and welding at the Auto Steel Partnership website:

http://www.a-sp.org/publications.htm

 

[metengr]

The AWS Welding Journal that GRoberts mentioned is the Nov, 2008 issue. Great place for welding information.