临界区退火温度对舰船用低碳高强钢组织和性能的影响

Effect of Intercritical Annealing Temperature on Structure and Properties of Low-Carbon High-Strength Steel for Shipboard

对舰船用低碳高强钢进行900℃奥氏体化淬火+不同温度(770,790,810,830℃)临界区退火+500℃回火处理,研究了临界区退火温度对试验钢显微组织和力学性能的影响。结果表明:随着临界区退火温度的升高,退火后形成的板条马氏体和贝氏体发生回复,趋于合并而呈块状特征;在770℃退火条件下,试验钢的强度较低,-20℃冲击功较高,冲击断裂模式为韧性断裂;当退火温度升高到790℃及以上时,试验钢的强度增大,冲击功下降,断裂模式转变为准解理断裂,并且冲击功随温度升高进一步下降,拉伸性能则变化不大。

Low-carbon high-strength steel was treated by austenitizing at 900℃and quenching,intercritical annealing at different temperatures(770,790,810,830℃),and tempering at 500℃.The effects of intercritical annealing temperature on the microstructure and mechanical properties of the test steel were studied.The results show that with the increase of intercritical annealing temperature,the recovery of lath martensite and bainite formed after annealing occurred,the lath martensite and bainite tended to merge and show block characteristics.Under the amealing condition of 770℃,the strength of the test steel was lower,the impact energy at-20℃was higher,and the impact fracture mode was ductile fracture.When the annealing temperoture rose to 790℃or above,the strength of the test steel increased,the impact energy decreased,and the fracture mode changed to quasi-cleavage fracture.The impact energy decreased farther with increasing temperature,and the tensile properties changed little.