welding hardened toolsteel

By cas

Date 11-19-2005 23:10

In the metal stamping industry, we occassionaly have the "OOPS!" in the pressroom that cracks a piece of tool steel and our local welder guy is lately booked up. We have in house heat-treat, a little GTAW runner, and my hands/eyes are capable to "zap" some of these back together, for a temporary patch until a new toolsteel piece can be machined,HT'd,EDM'd,fit and ready togo. Sometimes the turn around can shut our customers down for days,weeks,ect. and that just can't happen. I'm having trouble finding the "right" filler for these little projects; both what IS the right rod, and where do i get it? my local consumable supplier is unsure, but if can give the rep the type of filler, I feel confident he can get it in small quantities I need(1-2#'s of 1/16,5/32 would last a couple years). The types of steel for repair would be 4140, A2, D2, & CPM M2,M4 if possible on the pm stuff. Any advice on pre-heat temp's/post weld temper would also be extremely greatfull.
thanks, Cory.

By ownmind (*)

Date 11-21-2005 08:50

Preheating would be the most important issue if youre welding hardened tools. Mostly, hardened tool steels have very little elongation and are extremely brittle that leave them very vulnerable to cracking due to thermal stresses that develop during welding. The important issue is to weld with AS LITTLE AMPERAGE as possible at all times. Through cleaning is also an important step to avoid contaminated or porous welds. Here are the basic pre-heat temperatures. However these are only idicative and pre-heat temps can vastly vary.

1. High Speed Steels: Around 1100F
2. Oil Hardened Tool Steels: Around 320F-400F
3. Air Hardened Tool Steels: Around 650F-850F
4. Hot Working Tool Steels: Around 750F-878F

Do not forget to maintain the interpass temperature. It should remain around the preheat temp for maximum success. It is also a good idea to hot-peen each weld-deposit to relieve as much stress as possible. Post heat thumb-rule is, on most occassions to the same degree as pre-heat temp. It is better to slow cool the weld by covering it with some heat-retarding material.

I wouldnt suggest you weld more than 4 layers on tool steels. If you should overlay more than 3-4 layers, use a more ductile and tough weld wire with good elongation property for the root passes and weld the final 2 layers with tool steel wire.

There is one company in Charlotte, NC called Cronatron Welding Systems (www.cronatronwelding.com) that can provide you with filler wires. They can probably help you establish a weld-procedure as well. Good luck.

By cas

Date 11-22-2005 02:23

Thank you extreemly!!! I think I've gotten the pre-heat down; done a few forms, and one unexpected cut-edge(este no bueno:( ) with the best welds done w/ ER308-x. Guess i need to talk to cronatron. 1 more question, can you explain HOT-PIENING? just tapping on the weld, right after it's done? Is there special hammers for this or will regular slag chipping or auot-body piens work to get the effect neccessary? Once again thanks:) This has to be the best info I've gotten on the the topic other than "it's very difficult and there are proffessionals out there, who do this for a living". Well, I'm not trying to make a living at it, just want to be more versitle and do what I can, "in a pinch" to keep the company rollin'.

By ownmind (*)

Date 11-22-2005 08:03

Yes hot peening is the same as tapping on the weld while it is hot. Do not ever cold peen tools after welding. There is a peening tool available and Cronatron can probably help you with that as well. You can use a ball pin hammer (tap it with the ball pin side). One more thing. Do not peen with something with a sharp edge. Make sure the face of the hammer you're using is blunt and round. Good luck!!

Ownmind

By cas

Date 11-23-2005 00:37

got in touch w/ cronatron(sort of), the e-mail/telephone-tag game is in full effect. once again , much thanks. these types of specialty things aren't always easy to get to even w/ "all the pro's" out there giving .02,.25, even $1.10 at times, there are a few "recently balding" types walking around at my local supplier. with the info you provided maybe it will give thier rogain time to take effect and we'll all be on to the next knoggin scratcher. like i said thanks,and glad to know there are folks out there willing to chime in with productive info:)

By ziggy

Date 08-05-2006 00:26

just curious, but how did this all turn out? did cronatron provide what you were looking for? were you able to produce a welding procedure?
thanks,
ziggy