Projection Weld HSLA Steel

Date 04-22-2003 17:06

I have a question or two about what you are finding out about your welds. First, Is the nut failing and thereby not meeting requirements?
Second, Is the weld failing (or the base material failing) to hold the nut and thereby not meeting the requirements?

I have ran into fastener problems and found that high strength fasteners can fail when welded due to the heat changing the heat treat of the high strength bolt/nut.
John Wright
PS. Also supply the process used and filler material/base material ASTMs and thicknesses and what parameters you have tried and does not work.

By jwright650 (*****)

Date 04-22-2003 17:18

After reading your post you have already answered most of my questions,
John Wright

By jwright650 (*****)

Date 04-22-2003 17:34

Are you welding more than one nut at a time or is the 7/16" nut with 4 projections the only piece being welded?
If multiple nuts are being welded, is the balance of currents and force equal between the nuts?
Is the 4 projections 1.3mm enough to adequately hold?
John Wright

By robo90124 Date 04-22-2003 18:08

I am welding one nut at a time.

I looks as if the base material (1.8mm HSLA steel) is acting as a heat sink and not allowing the projections on the 7/16" nut to penitrate.

I have tried adjusting my current, weld time, pressure, introduced upslope to change the current density, Elkinite electrode on the base material, and also tried to use temper.

By pipewelder9229 Date 05-19-2003 05:38

we are currently welding to navy spec.s and any time you weld hsla material you are requird to preheat and hold a specifed interpass temp. depending on the metals thickness if your hsla materia is 1" or less in thickness try using a 125 degree preheat if you are only putting 1 pass on you wont have to worry about your interpass

By jwright650 (*****)

Date 05-19-2003 11:51

Pipewelder this guy is using a projection type process. I know what you are trying to say though and maybe a certain amount of preheat will help. This process is used for sheet steel or stamped out panels like fender inner liners for cars, where the nuts are on the backside are centered over the hole and welded. This guy has nuts which have 4 tits that stick out 1.3mm each and it gets forced into the steel with pressure and then current is applied melting the tits to the sheet forming weld nuggets. I've seen it done but I am not knowledgable enough on the subject to help him out with his problem. I was hoping someone would offer more help for this guy after I had covered the basics.
John Wright

By pipewelder9229 Date 05-20-2003 06:40

thanks for clearin that up john sounds intersting