Cr/Moly Tig welding wire comparison.

Date 08-30-2002 11:06

I wonder if anyone can compare some Cr/Moly tig welding wires with what we are currently using here in Australia?
The welding wire we use is called High Test and its classification is AWS A5.2 R60.
It has a typical rod analysis: C: 0.12%, Mn: 1.17%, Si: 0.25%,
S: 0.009%, P: 0.015%, Balance: Fe.
All weld metal tensile strength: 425 MPa.
Elongation: 28%
I'm interested in comparing it with ER70S2, ER70S6 and ER80S-D2 which I believe are the recommended filler wires for 4130 cond. N Chrome/Moly tubing.
I'm particularly interested in tensile strength and elongation properties in comparison with what we are using currently.
Any replies would be much appreciated.
Regards Andrew.

By GRoberts (***)

Date 08-30-2002 16:17

I am certainly not an expert on welding Cr-Mo tubing with undermatching filler metal, but I can tell you a few things about the fillers you are questioning about.

First thing, is the R60 you are using is actually an oxy-fuel mild steel welding rod. The tensile strength is 60 ksi or 413 MPa. The ER70S-2 and ER70S-6 have a 70 ksi tensile strength, or 482 MPa. The main difference between them is the ER70S-6 has more deoxidizers (Si and Mn). The specification for these is AWS A5.18. The ER80S-D2 is found in AWS A5.28, and has alloy additions of 1 3/4 Mn and 1/2 Mo. Tensile strenght is 80 ksi or 551 MPa. Minimum elongations for ER80S-D2 is 17% as welded, and for both ER70S-2 & 6 is 22% minimum. These are just the minimum specified though. For actual results, you might check out the ESAB, Hobart, or Lincoln Electric websites. They usually have that info on data sheets.