METALLURGICAL FACTORS INFLUENCING THE MAGNETIC ANALYSIS OF SURFACE HARDENED AND TEMPERED STEEL.
Final progress rept.,
CONNECTICUT UNIV STORRS
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An electron microscope study of microstructural changes induced by progressive tempering of carburized, oil quenched, refrigerated -100 F and unrefrigerated 18 - x 34 - x 34 -in. specimens of H-8620 steel showed a significant magnetic change to accompany the appearance of percarbides in martensite plates while retained austenite and residual stress have remained unchanged. Retained austenite was found to influence magnetic measurements. Distributions from surface into core were determined for retained austenite and residual stress resulting from 1650 F, 1 12 hour carburizing soild followed by oil quenching, brine quenching, oil quenching and refrigerating at -100 F, and liquid nitrogen quenching for both 18 - and 14 - in. thick specimens. All attempts to effect residual stress relaxation by exposure to a magnetic field were unsuccessful. Author