Mechanical Properties in weld HAZ A569 steel 1

[WeldWoman]

I was wondering if there is any data I could find on typical mechanical properties in the heat affected zone after welding A569? The base material is tearing at the toe of the weld, although the welds remain intact. We are trying to determine if this could be due to the different mechanical properties in the HAZ, using FEA. Thank you!

 

[metengr]

The base material is tearing at the toe of the weld, although the welds remain intact.

This statement alone suggests to me you have cracks along the toe of a weld after being in service - correct? Did you determine if the reason for the cracks was caused by weld undercut? Perhaps they are cracks caused by weld defects (lack of fusion) or fatigue crack propagation?

My advice is to confirm the damage mechanism for the observed weld toe cracks by having a sample or section removed for proper metallurgical analysis. During the course of this analysis you can have a complete microstructural characterization of the weld metal, heat affected zone and base material, and you can have a microhardness traverse performed to establish the variation in hardness and obtain an approximate tensile strength for the weld, HAZ and base metal.

 

[WeldWoman]

There was some convexity, which is pretty common in GMAW welds. We are aware that geometry is a potential stress riser, and we have been discussing how accurately that particular discontinuity is reflected on the FEA analysis (not very well). No undercut and no other discontinuities, and the weld itself did not fail, nor did the weld tear off the base material at any point, so we do not believe this was lack of fusion. We also can’t look at the fracture surface because the part is repaired in service- we don’t have the option to get it back, so we are trying to model as much as we can using FEA. Since the grain structure in the HAZ is changed by the welding process, we were interested in using that data in our analysis. This said, I can’t find any information on the mechanical properties of a typical HAZ for mild carbon steel, and I am trying to see if that data exists somewhere?

Thank you for your help.

 

[metengr]

http://www.scirp.org/journal/PaperDownload.aspx?paperID=2246