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Effect of Warm Prestressing on Fatigue Crack Growth Curves at Low Temperatures

出版	ASTM International, 1985
URL	http://books.google.com.hk/books?id=BKp2zgEACAAJ&hl=&source=gbs_api

註釋Low-temperature fatigue crack extension is studied in precracked single-edge-notched specimens of AISI 4340 steel. Steady-state crack extension in tension-tension fatigue and cyclic loading in conjunction with warm prestressing (WPS) are particularly emphasized. Effects of WPS on the fatigue crack growth curve are demonstrated and discussed. Special attention is given to the cleavage fracture mode, which dominates the features of the fatigue crack growth curve below the ductile-brittle transition (DBT) temperature. In AISI 4340 steel, which is characterized by DBT, WPS affects the alternative fracture mode and therefore alters the lower and upper bound values Kth and KIfc, respectively. For a more complete view, the behavior of AISI 304 stainless steel is discussed. The experimental results at low temperatures are mainly interpreted in terms of a transition in the cumulative crack tip damage process, induced by characteristic values of the stress intensity range amplitudes (?K).