Experimental Study on Mechanical Properties of 35CrMo-GLG650 Steel Rods at Elevated Temperatures

Investigation of the mechanical properties of steel rods at elevated temperatures is important for the fire-resistant design and fire simulation analysis of steel rod structures. In China, GLG650 denotes a steel rod whose yield strength is not less than 650 MPa. A 35CrMo-GLG650 steel rod is manufactured with 35CrMo alloy structural steel using quenching and tempering methods. To investigate the mechanical properties of 35CrMo-GLG650 steel rods at elevated temperatures, tensile tests of four specimens are performed at 100 degrees C, 200 degrees C, 300 degrees C, 400 degrees C, 500 degrees C, 600 degrees C, and 30 degrees C. The test results show that the 35CrMo-GLG650 steel rods at 30 degrees C and elevated temperatures exhibit typical nonlinear characteristics with no obvious yield plateau. The mechanical properties of the 35CrMo-GLG650 steel rods at elevated temperature are obtained, and they are compared with those of other high-strength steels. When the temperature is below 300 degrees C, the reductions in the mechanical properties of the specimens are approximately 0.9. However, the mechanical properties of the specimens change significantly when the temperature exceeds 300 degrees C. At 600 degrees C, the reduction factors of the yield strength, ultimate strength, and elastic modulus are 0.56, 0.46, and 0.45, respectively. In this paper, equations for the nominal yield strength, elastic modulus, and ultimate strength of 35CrMo-GLG650 steel rods at elevated temperatures are proposed. Furthermore, a modified two-stage Ramberg-Osgood model for 35CrMo-GLG650 steel rods at ambient and elevated temperatures is proposed that can act as a reference for the steel rod structure at elevated temperatures.