回火温度对51CrMnV弹簧钢组织与性能的影响OA

The"quenching plus tempering"heat treatment was conducted on 51CrMnV spring steel.The test steel was held at 860℃for 5 min,quenched in oil for 4 min,and then tempered at 420,440,460,480℃,respectively.After each tempering cycle,the steel was water-quenched to room temperature to finalize the process.The objective was to determine the optimal heat treatment parameters.The results show that the microstructure of the treated steel primarily consists of tempered troostite.As the tempering temperature increases,carbides gradually precipitate,and tend to grow and distribute uniformly within the ferrite matrix.Both the hardness and tensile strength of the test steel decrease steadily with higher tempering temperatures.Specifically,when the tempering temperature increased from 420℃to 480℃,the tensile strength decreased from 1 699.0 MPa to 1 466.5 MPa,while the elongation after fracture in-creased from 8.0%to 10.8%,and the strong plastic volume decreased from 19.4 GPa·%to 17.4 GPa·%.Therefore,the spring steel tempered at 440℃following oil quenching from 860℃exhibited fa-vorable mechanical properties,achieving a tensile strength of 1 612.0 MPa and an elongation after frac-ture by 9.5%.The optimum tempering temperature was found to be between 445℃and 455℃,with the tensile strength and elongation after breaking in this range outperforming the mechanical properties at 440℃.