welding nitrided steel

Date 12-19-2007 18:39

We always send coated parts our for stripping before we weld any coated tool steels.
Never tried it with the coating on it, but I would guess is will produce a very hard and brittle weld with the high amount of carbon on the surface coating. I have always looked at it from the point if I do it worng and it does not work, I will have to make a new detail and replace the one I ruined. This far outweights the small cost of stripping.

By DaveBoyer (*****)

Date 12-20-2007 06:35

MGD, You have aroused My curiouosity, is there a stripping process for nitriding? Nitriding goes IN the steel, not ON the steel.

By DaveBoyer (*****)

Date 12-20-2007 06:33

How thick is the nitrided layer? On many parts it is only about .0002" but I did hear from a guy who claimed to be able to get it to go 1/16" deep. My thinking is that a really thin layer might not add enough nitrogen to be a problem, BUT I AM ONLY GUESSING. I know that there are nitrogen strengthened stainless steels, but I don't know how much nitrogen it takes.

By MDG Custom Weld (***)

Date 12-20-2007 13:20 Edited 12-20-2007 16:35

Dave let me clarify. Titanium Nitride is a surface coating that needs to be stripped before welding. This is the gold coating that is on many taps, punches, and various steel working tools. Iron Nitride is what you are describing and yes that coating is not able to be stripped. It forms a case type of hardening that I have never seen greater than .008 thick (not to say it can't be deeper, but 1/16 seems impossible). This case usually ends up being 69-71 Rockwell C and is very wear resistant. We have welded parts with this coating without issue, but knowing the base metal is critical for pre/ post temp requirements. Depending on the size and area of the weld, it might need to be re-coated to maintain even wear when it goes back into service.

By DaveBoyer (*****)

Date 12-21-2007 04:29

MGD: I am familliar with the titanium nitride coating You described, and yes I was refering to the ordinary nitriding like on ejector pins, etc. The guy who claims to be able to nitride 1/16" deep offers this as a surface treatment on cement truck drums. He was supposed to send Me some samples so I could promote the process in My area, but I never got them, or more information.

By MDG Custom Weld (***)

Date 12-21-2007 12:05

Wow, the inside of an entire drum of a cement truck would be one heck of a coating job!! Maybe he has something that I have never seen before to get the coating that thick. My experience is with steel working tools and die sections, nothing to the extreme of an entire cement drum.