Optimization of Hardening Heat treatment of Oil Extraction Machine’s Cylinder Made of Stainless steel

Document Type : Original Article

Authors

1 Department of mechanical engineering, Semnan university

2 Department of Mechanical Engineering Tarbiat Modares University

Abstract

Hardening heat treatment is one of the most important processes used in manufacturing the oil extraction machine’s cylinder. During heating operations, thermal stresses are created. This would lead to internal defects because of screw pressure and finally cause failure and decreases in machine life time. In this paper, different heating heat treatment cycles for an oil extraction machine’s cylinder made of stainless steel AISI420 were investigated by experimental and numerical methods. Since the residual stress is the main factor that affects the failure in the cylinder, the cycle with minimum stress is chosen as an optimum condition. The accuracy of the results of the simulation process is evaluated by providing experimental samples. Also, different heat treatment cycles were designed by the TAGUCHI method. Then, tensile test specimens were prepared from experimental samples, and their mechanical properties were compared. Finally, preheating at 790 °C for 30 minutes, the second stage preheating at 900 °C for 30 minutes, the Austenitic process at 1056 °C for 30 minutes, Quenching in oil at 80 °C for 10 minutes, the first stage tempering process at 370 °C for 90 minutes and the second stage tempering process at 370 °C for 90 minutes was considered as the best condition for hardening heat treatment cycles.

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