Application of the microscopic and Mössbauer studies to the analysis of a marine diesel engine crankshaft

Abstract

ABSTRACTIn the paper, the issue of the material quality of the large-size crankshaft is discussed. In order to ensure the reliability and wear resistance of the crankshaft, its chemical composition was checked in detail, revealing also the presence of trace elements omitted in Standards. The mechanical characteristics of the material were measured using the samples taken from the upper and lower parts of the forging. The novelty of the quality analysis was the additional measurement with the conversion electron Mössbauer spectrometry method. High phase purity, homogeneity and isotropy of the investigated material were confirmed. The carbon-saturated ferrite was detected as dominating phase of about 95% content. The observed martensite structure appeared to be correct, and the material met the specification requirement. Only slight differences in atomic ordering of alloying elements in ferrite structure were observed between the upper and lower part region, which was not considered a threat. It was assumed that the confirmed chemical purity and homogeneity contributed to the high straightness of the tested material.