The micro-mechanisms of tempered martensite embrittlement in 4340-type steels

摘要: A study of the micro-mechanisms tempered martensite embrittlement was made on a series 4340-type steels in which contents manganese, silicon, and trace impurities, especially phosphorus sulfur, were varied. One plain-carbon steel also examined. The employed Charpy impact tests four-point slow-bend coupled with an elastic-plastic stress analysis, as well scanning electron fractography, Auger spectroscopy, transmission microscopy extraction replicas, magnetic measurements transformation retained austenite. results indicate that these TME phenomenon is intergranular problem caused by carbide precipitation prior austenite grain boundaries are already weakened segregated sulfur. intragranular concluded not to be primary significance steels, although it may contribute magnitude toughness trough.