TY - JOUR
T1 - Fatigue crack tip deformation processes as influenced by the environment
AU - McEvily, A. J.
AU - Velasquez, Gonzalez
PY - 1992
Y1 - 1992
N2 - The shape of a fatigue crack tip as influenced by an air or a vacuum environment has been investigated in two stainless steels and an aluminum alloy. Under plane strain conditions and at crack growth rates in the Paris region, the crack tip opening displacement (CTOD) is much larger in vacuum than in air, a circumstance attributed to strain localization in air due to the presence of moisture and the absence of strain localization in vacuum. In type 304 stainless steel, a strain-induced transformation from austenite to martensite occurs at the crack tip, and the extent of this strain-induced transformation in type 304 stainless steel is consistent with the degree of blunting taking place at the crack tip as influenced by the environment. In air, the extent of transformation is a function of the ΔK level, and as a result, the crack opening level is found to differ in a ΔK decreasing test as compared to a ΔK increasing test. Fatigue striations are observed in air but are absent in vacuum. It is proposed that the greater extent of blunting in vacuum is responsible for the absence of striations in vacuum.
AB - The shape of a fatigue crack tip as influenced by an air or a vacuum environment has been investigated in two stainless steels and an aluminum alloy. Under plane strain conditions and at crack growth rates in the Paris region, the crack tip opening displacement (CTOD) is much larger in vacuum than in air, a circumstance attributed to strain localization in air due to the presence of moisture and the absence of strain localization in vacuum. In type 304 stainless steel, a strain-induced transformation from austenite to martensite occurs at the crack tip, and the extent of this strain-induced transformation in type 304 stainless steel is consistent with the degree of blunting taking place at the crack tip as influenced by the environment. In air, the extent of transformation is a function of the ΔK level, and as a result, the crack opening level is found to differ in a ΔK decreasing test as compared to a ΔK increasing test. Fatigue striations are observed in air but are absent in vacuum. It is proposed that the greater extent of blunting in vacuum is responsible for the absence of striations in vacuum.
UR - http://www.scopus.com/inward/record.url?scp=0026908029&partnerID=8YFLogxK
U2 - 10.1007/BF02646014
DO - 10.1007/BF02646014
M3 - Artículo
SN - 0360-2133
VL - 23 A
SP - 2211
EP - 2221
JO - Metallurgical transactions. A, Physical metallurgy and materials science
JF - Metallurgical transactions. A, Physical metallurgy and materials science
IS - 8
ER -