The stress-wave analysis technique (SWAT) was used to monitor subcritical cracking in two heats of grade-250 18 percent nickel maraging steel exposed to circulating water at 70 and 165°F. The SWAT system consisted of sensors, amplifiers, filters (to eliminate extraneous noise) and an electronic counter and printer. The material investigated was from an air-melted (induction-stirred, ladle-vacuum degassed) 70-ton heat which was split to provide a second, vacuum-arc-remelted heat. The rolling practices employed in producing the air-melt and vacuum-arc-remelt sheet products were the same. The stress-corrosion tests were conducted using fatigue-precracked, single-edge-notched, tension specimens in conjunction with linear-elastic fracture-mechanics to determine effect of melting practice and long exposure times. In addition to the detailed information on the stress-corrosion crack-growth process made possible by SWAT, there were two noteworthy observations; viz. 1. (1) the vacuum-arc-remelt material was more susceptible to stress-corrosion cracking than the air-melt material and 2. (2) the mechanism of subcritical cracking was different at the two test temperatures. In 165°F water, the crack growth process was discontinuous indicating a diffusion-controlled mechanism; whereas, in 70°F water, there were no crack jumps until the onset of instability.