Analysis of Causes of Quenching and Tempering Cracks in 42CrMoA Geological Drill Pipe Joint
A comprehensive analysis was conducted on the causes of failure of geological drill pipe joints processed with 42CrMoA through testing items such as chemical composition,mechanical properties,metallography,and scanning electron microscopy energy spectrum analysis of failed joints.The analysis results show that the failure is caused by quenching crack,because the existence of chromium carbide inclusions in raw materials and uneven matrix structure leads to the formation of stress concentration points inside the steel,which damages the uniformity of the steel and then causes quenching cracks.The crack propagates along the stress concentration point of the rounded chamfer at the joint shoulder,which is the stress concentration point,arc and through-shape composite cracks are formed.Some suggestions to reduce the occurrence of such failure were put forward.
42CrMoAdrill pipe jointcause of failureinclusionuneven structure
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