IWE question 2

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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