Effect of Alloy Composition on Stress Corrosion Cracking of Fe-Cr-Ni Base Alloys

Abstract

Abstract This study investigated the effect of alloying on the behavior of Fe-Cr-Ni base alloys in boiling MgCl2 solutions. Alloys included commercial Fe-Cr-Ni alloys; ternary Fe-Cr-Ni alloys to 40% Cr; fourth-component alloys with specific alloy bases; fourth-, fifth-, and sixth-component alloys. The primary experimental measurements were time-to-breaking of wire specimens. In addition, polarization, potential time, current decay, constant potential cracking, and metallographic studies were conducted. Alloys of very substantial improvement in resistance to cracking were found. The most effective alloy additions were found to be aluminum, beryllium, and carbon. Lowering chromium to the 10-15% range was also found to be very effective in preventing cracking. The results are discussed in terms of the slip-step dissolution model of stress corrosion cracking.