Bend tests of weld cladding

Date 07-20-2005 10:31

During side bend testing of, for example, austenitic stainless steel weld overlay on carbon steel, we often have a problem of cracking that start between the runs of the top layer. If we look at ASME IX, QW163 acceptance criteria for bend test, it state that open discontinuities occurring at the corners of the specimen shall not be considered, unless it is a welding defect. If the overlap of the welder is not close to 50%, these inter run area can be very severe stress raisers. What I would like to know is if you normally remove the weld cap to eliminate these stress raisers or do you leave them in place. And secondly, how do you evaluate cracks starting from the corners, visual inspection or under a microscope, and how long can these cracks be?

Regards
Joe

By Bill Mc (**)

Date 07-20-2005 12:40

As shown on QW-462.5(a) I normally "prepare" the weld overlay surface. I do it by milling "as welded" surface to clean-up prior to doing the bend tests. The qualified overlay thickness now is the distance from the prepared surface to the approximate weld interface. The milling does not remove much weld overlay stock, and the ends or corners of the overlay remain as welded.

If you are seeing cracks at the corners of the overlay, can I ask what is the width of the weld overlay on the test plate?

By johannes (*)

Date 07-21-2005 05:35

The width of our weld overlay is normally in the order of 100mm. We do not have cracks at this transition from the base metal to the overlay, but between the runs of the top layer, we normally use about two layers of weld overlay. We do not normally prepare the top layer and leave it in the as welded condition. My personal opinion is that this as welded profile sometimes creates severe stress raisers, and if you bend it, even ductile material like austenitic stainless steel will start to crack. This cracking is not due to any problems with ductility and is creating unnecessary difficulties with the interpretation of the results.

Regards
Joe