Two Z-shape impeller vanes failed. The vane material was 14-hard type 301 stainless steel. The vanes were of two-piece construction, with a longitudinal weld. Analyses indicated that the vanes had not been solution annealed after welding, leaving the heat-affected zone above the welds in a highly sensitized state. The sensitized material lost corrosion resistance, became embrittled along the grain boundaries, and finally failed by intergranular cracking. Use of type 410 martensitic stainless steel was recommended.
Harry E. Ebert, Intergranular Cracking and Failure of Stainless Steel Vanes from a Closed, Riveted Impeller, Handbook of Case Histories in Failure Analysis, Vol 1, Edited By Khlefa A. Esaklul, ASM International, 1992, p 278–283, https://doi.org/10.31399/asm.fach.v01.c9001086
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