Cause Analysis on Inspection Disqualification of 32CrMo4 Steel Perforating Gun Pipe

The pass rate with ultrasonic inspection for 32CrMo4 steel perforating gun pipe of a company was so low, and the disqualified perforating gun pipe had been tested and studied in depth by means of macro and micro morphology analysis, macrostructure test and heat treatment progress analysis. The result show that the disqualified perforating gun pipe had longitudinal cracks which caused by quenching with water instead of oil in actual production for decreasing cost and pollution. However, quenching with water could easily caused cracks for over stress, so the pass rate of the perforating gun pipe had been reduced greatly. According to reducing carbon content, using 26CrMo4 steel instead of 32CrMo4 steel could improve the pass rate and met with the original using requirement of performating gun pipe.