API ICP Programs API-571 Question # 11 Topic 2 Discussion
API-571 Exam Topic 2 Question 11 Discussion:
Question #: 11
Topic #: 2
A nickel-based buttering layer is often used when welding austenitic stainless steels to carbon steels to avoid dissimilar weld metal cracking because:
A.
Austenitic stainless steels are susceptible to chloride cracking.
B.
Nickel base alloys are much softer than austenitic stainless steels.
C.
The coefficient of thermal expansion is better suited to avoid cracking.
D.
You can avoid the need for post weld heat treatment to lower hardness.
“Nickel-based buttering is often used as an intermediate layer to reduce thermal stress mismatch during welding of ferritic and austenitic materials.”
“Nickel alloys have a coefficient of thermal expansion closer to that of both stainless steels and carbon steels, reducing stress concentrations and mitigating dissimilar weld cracking.”
“This technique also assists in achieving metallurgical compatibility and mitigating solidification cracking.”
Hence, option C is correct as it directly relates to minimizing thermal expansion mismatches.
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