[TheForge] Welding Tool Steel

[debmiller at fuse.net]

Dave,
I do not have any experience welding tool steel, but I do have a lot of experience completing "hot welds" in power plants, as well as grinding out cracks in 60 ton steam turbine casings and welding back deep vee's successfully.

There are two "secrets". Preheat, interpass temperature control and post heat stress relieving. The challenge in that industry was heating up a 60 ton turbine casing to a 450 degree preheat, uniformly, keeping welders from pasing out from the heat, and then stress relieving the whole thing by taking it up to 1150 degrees for 8 hours and then letting it cool down while insulated, another couple of days.

I would think that if he is not brazing the joint, he may be preheating the dies pretty hot for welding, possibly the source of the color difference with the surface metal, and then welding over a cover pass with a more corrosion resistent filler. Then heat the whole thing up to stress relieve it and let it cool very slowly. 

The heat treating experts can tell you what temps to use without affecting the temper of the dies.

Ray Miller
Cincinnati

---- David Childress <trollkeep at gmail.com> wrote: 
> I have a work problem I am hoping someone here knows about.  I work in
> a stamping plant and sometimes (Maybe often) we break die blocks and
> have to weld them back together.  Usually they break again.  We had a
> welder in Indianapolis who could weld things we could not and his
> welded blocks never broke again.  He has been welding tool steel for
> 45 years and now only works sometimes and has too much to do.  I think
> that he has been flowing brass through the broken places and then TIG
> welding the surface.  He does no finish work but his welds are narrow
> and take no time to clean up, better than anything my welders can do.
> My die makers say you need a big "V" and then fill it up to get a
> strong weld.  It dows not look like the old outside welder does more
> than break sharp edges and his welds never break.  I had a block he
> welded break across his weld and there was something not steel behind
> his weld and the new break did not follow the old break at all.
> 
> How does he do this?
> 
> David Childress
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