Hardness and GMAW-Spray
Hardness and GMAW-Spray
(OP)
Looking for suggestions on how to reduce my weld and HAZ hardness readings when using GMAW Spray on carbon steel material. I often see readings well above 250 BHN on a wide range of thk.
Thanks,
Uglyspec
Thanks,
Uglyspec





RE: Hardness and GMAW-Spray
RE: Hardness and GMAW-Spray
Thanks,
RE: Hardness and GMAW-Spray
Substantially greater hardness readings were recorded on root and cap side surfaces of 1 1/4" coupons where low interpass temps recorded - Cap pass interpass temp range from 260F to 350 F.
RE: Hardness and GMAW-Spray
with true spray transfer it does not seem that low heat input would be an issue unless you are traveling at a very high rate.
Have you seen much difference in weld hardness between 70S-2 and 3. I ask because in my experience using the GTAW process, we get much softer welds using S-3 filler.
Keep in mind that HAZ hardness will also be affected by the base metal chemistry. Have you looked at the CE for the material in question?
RE: Hardness and GMAW-Spray
The use of a mix of Argon and Carbon Dioxide (SG-AC-12%) will ensure the deoxidizers are used for that purpose and do not increase the alloy content. Both Manganese and Silicon are used as deoxidizers in filler metals. If they are not utilized for deoxidizing the weld pool they become alloy constituents, thereby increasing the Manganese and Silicon content of the weld deposit and increasing the hardness values.
Slow cooling, high heat input, high preheat, high interpass temperatures will also reduce the hardness of the weld.
Best regards - Al