低屈强比高强耐候钢的CCT曲线及性能

利用膨胀法并结合金相-硬度法对研制的一种低屈强比高强耐候钢进行了奥氏体连续冷却转变(CCT)曲线测定,并对其力学性能和耐蚀性能进行了研究。结果表明:该试验钢抗拉强度达575 MPa,屈强比为0.75,冲击性能优良,耐蚀性明显优于Q345B钢;当奥氏体化后的试验钢以0.1~100 ℃/s冷却速率冷却至室温时,随冷却速率增加其显微硬度由131 HV0.5增加至218 HV0.5;其中当冷却速率小于1 ℃/s时,其组织由铁素体+珠光体构成;当冷却速率为1~20 ℃/s时,其组织由铁素体+珠光体+贝氏体构成;当冷却速率为20~100 ℃/s时,珠光体消失,其组织主要由铁素体+贝氏体构成。

CCT curves and properties of low yield rario high strength weathering steel

Continuous cooling transformation (CCT) curves of a low yield ratio high strength weathering steel were plotted by means of expansion method combined with metallographical and hardness methods, and the mechanical properties and corrosion resistance of this steel were studied. The results indicate that the tensile strength of the tested steel reaches 575 MPa with 0.75 yield ratio, the impact property is excellent, and the corrosion resistance is obviously better than Q345B steel. When the tested steel after austenitizing is cooled to room temperature at a cooling rate of 0.1-100 ℃/s, its microhardness value increases from 131 HV0.5 to 218 HV0.5 with the increase of cooling rate. When the cooling rate is below 1 ℃/s, the microstructure of the steel is composed of ferrite and pearlite. When the cooling rate is in the range from 1 ℃/s to 20 ℃/s, the microstructure is composed of ferrite, pearlite and bainite. When the cooling rate is in the range from 20 ℃/s to 100 ℃/s, the pearlite disappears and the microstructure is mainly composed of ferrite and bainite.