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Temper Embrittlement Susceptibility and Toughness of A 508 Class 3 Steel

出版	ASTM International, 1989
URL	http://books.google.com.hk/books?id=wZ14zgEACAAJ&hl=&source=gbs_api

註釋A correlation has been established between the scatter in Charpy and fracture toughness results of an ASTM Specification for Quenched and Tempered Vacuum-Treated Carbon and Alloy Steel Forgings for Pressure Vessels (A 508-84a) Class 3 (UNS K12042) pressure vessel forging steel and the appearance of intergranular facets on the rupture surfaces of specimens tested at low temperatures. Extent of the intergranular rupture has been found to increase with prolonged aging at 500 to 550°C or following an embrittling treatment known as step cooling. Both intergranular rupture and the resultant increase in ductile to brittle transition temperature were reduced or eliminated by a de-embrittling treatment at temperatures ranging from 630 to 660°C, with optimum results obtained at 640°C. Auger analyses carried out on specimens exhibiting cleavage and intergranular rupture have shown segregation of carbon, molybdenum, sulfur, and, in particular, phosphorus at the grain boundaries.