HAZ 3

[Downhand]

Can anyone tell me approximately how wide the HAZ would be for a welded 6" STD wall butt weld? I realize it has alot to do with heat input, however, let's assume 1/8" 7018 was used to weld the joint at average heat. I am looking for a real rough estimate here. I'm not sure if it would be around 1 millimeter or 1 inch or somewhere in between.

Thanks

 

[metengr]

For the HAZ width, figure around 3/16" max as a safe assumption.

 

[gtaw]

3/16 inch sounds like a fair estimate.



Best regards - Al

 

[Ron]

Agree. In small welds that I've cross-sectioned and etched, that's about the distance I've seen.

 

[Downhand]

Good info. Ron, have you crossed sectioned and etched anything bigger or any heavywall? Could anyone give me an idea how wide the HAZ would be on bigger and heavier pipe? I am interested because my specs call for the HAZ to be hardness tested in some cases and I am not entirely sure as to how far out from the toe of the weld to catch the HAZ. As well, when cross sectioning and etching is the entire area that appears the HAZ. I have been told that this area is broken down into more than just the HAZ. Is this true?

Thanks

 

[metengr]

Downhand;
This is not as simple as measuring some distance from the edge or toe of the butt weld, “x” distance. If you need to conduct field or lab hardness testing of the base metal HAZ, you should have the completed weld region chemically macroetched to locate the heat affected zone. Once this is completed, you know precisely the width of the HAZ, and can conduct hardness testing with some assurance. A good chemical macroetch for locating the weld HAZ is an ammonium persulphate chemical etch.

The weld region in ferrous materials contains the following; weld deposit, fusion boundary (where the weld and base metal have mixed from melting) followed by the region along the base metal beyond the fusion zone where the original metal structure has been altered from exposure to heat from welding. This altered region is the HAZ and will be delineated by macroetching for hardness testing.

http://www.welding-technology-machines.info/inspection-and-testing-of-welds/etch-test.htm

 

[Ron]

downhand...even in larger welds, the HAZ doesn't get tremendously larger in steels.

A quick and dirty etchant is hot muriatic acid.