The Stability Control to the Mechanical Properties of High-pressure Gas Cylinder Industrial Production by Using Stability Indicators

To ensure a smooth production, some stability indicators, including mean (mu), standard deviation (sigma), standard deviation coefficient (V), as well as the probability (P) of variable values that fall within the scope of the standard were introduced to evaluate and to control the chemical composition and mechanical properties of seamless gas cylinder 30CrMo-M. Stability levels were defined according to the enterprise performance appraisal system. By using SPSS and MATLAB software, a regression equation was established that evolved chemical composition, tensile strength, yield strength and elongation. Tensile strength and yield strength are positive correlated with C, Si, Mn, and elongation is just the opposite. According to the stability indicators and regression equations, the entire mechanical properties meet the standard requirements by reducing Mn, Si content by 0.02%, while maintaining C content constant. According to the stability indicators, the best heat treatment system, quenching at 930 similar to 935 degrees C for 40 minutes and tempering at 580 similar to 595 degrees C for 90 minutes, was established.