A welding fabricator has to qualify welders for joining mild steel pipe to type AISI 304 stainless steel pipe
using E309L SMAW electrodes. The procedure qualification permits the use of either one mild steel and one
stainless steel pipe, or two mild steel pipes on either side of the joint, but to minimise costs all the
qualification tests are performed with mild steel pipe on both sides of the joint. Most of the specimens fail
the qualification tests. The root pass frequently contains a crack after welding, or bend test specimens
crack in a brittle manner in the root pass. Discuss possible causes of these failures, and comment on
whether the pass rate is likely to improve if the tests are repeated with stainless steel pipe on one side of the joint.
Alloy | Cr | Ni | C | Mn | Si | Mo | Cu | N |
AISI 304 | 18.5 | 10 | .04 | 1.5 | 0.4 | .1 | .1 | .03 |
E309L | 24 | 13 | .03 | 1.5 | .4 | .1 | .1 | .06 |
E312 | 29 | 9 | 0.1 | 0.95 | 1 | .1 | .1 | .05 |
Mild steel | .1 | .1 | .1 | .8 | .05 | .1 | .008 |
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