【摘要】 通过研究连续冷却和等温相变规律,确定了27Si Mn钢贝氏体相变的条件,设计了其两段淬火+低温回火热处理工艺,从而获得贝氏体组织。结果表明:当过冷奥氏体以3~40℃/s连续冷却时,存在贝氏体相变,并且随着冷速增加,贝氏体量先逐渐增加然后逐渐减少;贝氏体等温相变温度区间为390~450℃。910℃加热30 min,油冷至(450±10)℃再空冷至室温分段淬火,然后250℃回火低温40 min,27Si Mn钢获得贝氏体组织,其抗拉强度890 MPa,屈服强度693 MPa,断后伸长率28.0%,断面收缩率67.0%,冲击功64 J,具有良好的强度、塑性和韧性匹配。更多还原

【Abstract】 The bainite transformation conditions were revealed by investigating the continuous cooling and isothermal transformations of steel 27 Si Mn. The two-step quenching and low temperature tempering treatment were designed and put forward to obtain bainite. The results show that bainite transformed from overcooling austenite when cooling rate is 3-40 ℃ / s,and the volume fraction of bainite increases first and then decreases with the increasing of the cooling rate. The temperature of bainite isothermal transformation is 390-450 ℃. The microstructure of the steel revealed bainite by austenitized at 910 ℃ for 30 min,and oil quenched to 450 ± 10 ℃,then air quenched to room temperature,then it is tempered at 250 ℃ for 40 min. Its mechanical properties has a good combination of strength,plasticity and toughness. The tensile strength,yield strength,percentage elongation after fracture,percentage reduction of area and impact absorbing energy of the steel are 890 MPa,693 MPa,28. 0%,67. 0% and 64 J,respectively.更多还原