welding P20 tool steel (nitrided) 1

[408]

Hi I work in the toolmaking industry, and often we have to repair plastic injection moulding tools made of P20 tool steel that has been nitride hardened. We use tig welding. The end result is usualy poor because of the nitrogen gas, from the nitriding process causes bubbling of weld material. This can be overcome to some degree by grinding away the surface before welding, but it will still bubble around the edges. Can anyone surgest anything that could help. Thanks, Harvey.

 

[Goahead]

Hi,
it sounds like mission impossible...
All the nitrided layer, for about twice the original thickness of the layer, should be removed mechanically.
Maybe it would help to look for a suitable substitute for nitriding, in the form of hardfacing: that should be easier to repair by welding.
Sorry.

http://www.welding-advisers.com/

 

[408]

Thanks Goahead, I am just hoping someone has a technique not fought of. Nitriding is used extensively in toolmaking because it is a low temmpture process and therefore low distortion.