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Abstract: Room temperature cavitation tests of vacuum annealed type 316LN stainless steel were performed in pure mercury and in mercury with various amounts of metallic solute to evaluate potential mitigation of erosion/wastage. Tests were performed using an ultrasonic vibratory horn with specimens attached at the tip. All of the solutes examined, which included 5wt% In, 10wt% In, 4.4wt% Cd, 2wt% Ga, and a mixture that included 1wt% each of Pb, Sn, and Zn, were found to increase cavitation-erosion as measured by increased weight loss and/or surface profile development compared to exposures for the same conditions in pure mercury. Qualitatively, each solute appeared to increase the tenacity of the post-test wetting of the Hg solutions and render the Hg mixture susceptible to manipulation of droplet shape. [Copyright &y& Elsevier]

Abstract: An extensive fatigue testing program on 316LN stainless steel was recently carried out to support the design of the mercury target container for the spallation neutron source (SNS) that is currently under construction at the Oak Ridge National Laboratory in the United States. The major objective was to determine the effects of mercury on fatigue behavior. The S–N fatigue behavior of 316LN stainless steel is characterized by a family of bilinear fatigue curves which are dependent on frequency, environment, mean stress and cold work. Generally, fatigue life increases with decreasing stress and levels off in the high cycle region to an endurance limit below which the material will not fail. For fully reversed loading as well as tensile mean stress loading conditions mercury had no effect on endurance limit. However, at higher stresses a synergistic relationship between mercury and cyclic loading frequency was observed at low frequencies. As expected, fatigue life decreased with decreasing frequency, but the response was more pronounced in mercury compared with air. As a result of liquid metal embrittlement (LME), fracture surfaces of specimens tested in mercury showed widespread brittle intergranular cracking as opposed to typical transgranular cracking for specimens tested in air. For fully reversed loading (zero mean stress) the effect of mercury disappeared as frequency increased to 10Hz. For mean stress conditions with R-ratios of 0.1 and 0.3, LME was still evident at 10Hz, but at 700Hz the effect of mercury had disappeared (R =0.1). Further, for higher R-ratios (0.5 and 0.75) fatigue curves for 10Hz showed no environmental effect. Finally, cold working (20%) increased tensile strength and hardness, and improved fatigue resistance. Fatigue behavior at 10 and 700Hz was similar and no environmental effect was observed. [Copyright &y& Elsevier]