THE FRACTOGRAPHY OF STRESS-CORROSION CRACKING OF 310 STAINLESS-STEEL - CRYSTALLOGRAPHIC ASPECTS AND THE INFLUENCE OF THE STRESS INTENSITY FACTOR

The microfractography of transgranular stress corrosion cracking (TSCC) of annealed 310 stainless steel tested in boiling MgCl//2 solution was studied in relation to the behavior of crack velocity as a function of the stress intensity factor K. The observations indicated that TSCC occurred by a series of discontinuous cleavage-like crack jumps of approximately 0. 3 mu m in the near-threshold region and 1. 0 mu m in stage II of the crack velocity curve. Cracking occurred predominantly on left brace 100 right brace planes, with a preferred LT AN BR 110 RT AN BR crack propagation direction. Striation-like markings were often present perpendicular to the LT AN BR 110 RT AN BR crack propagation direction. The TSCC crystallography identified here and in previous studies on face-centered cubic (f. c. c. ) metals is discussed with respect to different propagation mechanisms which have been proposed to account for crystallographic TSCC and with respect to the probable arrest mechanism for the crack jumps.