Effect of Preheat and Post Weld Heat Treatment on the Properties of AISI 4140 Steel

In this work the effect of preheat and post weld heat treatment on the properties of AISI 4140 steel was evaluated. TheExperements were carred out on three different conditions: 1-without preheat and without post weld heat treatment. 2-with preheat and without post weld heat treatment. 3-with pre heat and with post weld heat treatment. Welding process was SMAW. The effect of preheat and post weld heat treatment on mechanical properties was evaluated by mechanical testes such as impact test، tensile test، hardness test and bend test. The changing of microstructure was studied by optical microscope. With preheat and post weld heat treatment the mechanical properties of weld area should be controlled. The post weld heat treatment can improve the fracture toughness.