Influence of Pre-Stress Magnitude on Fatigue Crack Growth Behavior of Al-Alloy.

Abstract

From tensile overload to shot peening, there have been many attempts to extend the fatigue properties of metals. A key challenge with the cold work processes is that it is hard to avoid generation of harmful effects (e.g., the increase of surface roughness caused by shot peening). Pre-stress has a positive effect on improving the fatigue property of metals, and it is expected to strength Al-alloy without introducing adverse factors. Four pre-stresses ranged from 120 to 183 MPa were incorporated in four cracked extended-compact tension specimens by application of different load based on the measured stress⁻strain curve. Fatigue crack growth behavior and fractured characteristic of the pre-stressed specimens were investigated systematically and were compared with those of an as-received specimen. The results show that the pre-stress ranged from 120 to 183 MPa significantly improved the fatigue resistance of Al-alloy by comparison with that of the as-received specimen. With increasing pre-stress, the fatigue life first increases, then decrease, and the specimen with pre-stress of 158 MPa has the longest fatigue life. For the manner of pre-stress, no adverse factor was observed for increasing fatigue property, and the induced pre-stress reduced gradually till to disappear during subsequent fatigue cycling.

• Authors: Chunguo Zhang, Weizhen Song, Qitao Wang, Wen Liu
• Journal: Materials (Basel, Switzerland) (Materials (Basel)) Vol. 11 Issue 8 (Jul 24 2018) ISSN: 1996-1944 [Print] Switzerland
• PMID: 30042311 (Publication Type: Journal Article)