welds crack sometimes

By jer

Date 04-04-2006 18:48

A potential new customer is having problems with their welding source in that many welds are cracking, and evidently there not willing to search out the reason why.

Material is 3/8" 1018 CRS rod with a small plate tacked on about 4" in from each end. The plate is a stamping say 1/8" x 1 x 1 1/2" 1010 CRS.

The plate is case hardened to 50 Rockwell & then Nickel plated before welding, now approximately 15% will develop a crack right threw the center of weld. I don't know what filler or process the other guy is using, yet it seems that no heat is involved and I assume he's using mild steel.

What filler would work best? I would think that ones fighting the fact its case hardened. Maybe a 312 rod. Any thoughts appreciated.

By SWP

Date 04-04-2006 21:14

I venture to guess the cracking is tied to the Nickel plating. I'm no expert on plating, but there is a process called High-phosphorus Electroless Nickel which contains 9 to 11% Phosphorus. Phosphorus is known to promote hot cracking.

Again a guess, but I don't think the case hardening is related to the weld centerline cracking. Generally, centerline cracking is hot cracking.

If the cracking occured in the basemetal HAZ, that might lead you to look at HAZ hardness and Hydrogen embrittlement. The base metal carbon is low, the very thin case is adding little carbon to the melt, it really shouldn't matter?