超快速冷却工艺对780 MPa级低碳高强度结构钢组织和力学性能的影响  

Effects of Ultra Fast Cooling Processes on Microstructure and Mechanical Properties of 780 MPa Low-Carbon High Strength Constructional Steel

作　　者：冯路路 董宝奇 李萍萍 FENG Lulu;DONG Baoqi;LI Pingping(School of Mechanical Engineering,Jingchu University of Technology,Jingmen 448000,China;School of Materials and Metallurgy,Wuhan University of Science and Technology,Wuhan 430081,China;International Research Institute for Steel Technology,Wuhan University of Science and Technology,Wuhan 430081,China)

机构地区：[1]荆楚理工学院机械工程学院,湖北荆门448000 [2]武汉科技大学材料与冶金学院,湖北武汉430081 [3]武汉科技大学国际钢铁研究院,湖北武汉430081

出　　处：《热加工工艺》2020年第10期104-106,共3页Hot Working Technology

基　　金：湖北省自然科学基金项目(2018CFB304);湖北省教育厅科学研究项目(B2019216,Q20174301,Q20184302);荆门市科技计划项目(2018YFYB054)

摘　　要：采用不同的超快速冷却工艺试制了780 MPa级低碳高强度结构钢,结合金相显微镜、SEM扫描电镜分析了不同的冷却工艺对试验钢显微组织和力学性能的影响。结果表明:在相近的冷却速度下,随着终冷温度的降低,试验钢的显微组织中块状铁素体和粒状贝氏体的数量逐渐减少,板条贝氏体的数量增加,屈服强度和抗拉强度升高,伸长率降低。过大的冷却速度和过低的终冷温度使轧制过程中的位错与位错、位错与晶界之间的相互作用保留下来,有效地提高了试验钢的强度。过大的冷却速度使试验钢在低温冲击试验中表现为断口韧窝被严重拉长,小部分区域呈准解理状态,对裂纹扩展阻碍能力变差,韧性下降。The 780 MPa low-carbon high strength structural steel was produced by different ultra-fast cooling process.The effects of different cooling processes on the microstructure and mechanical properties of the steel were analyzed by means of metallographic microscope and SEM scanning electron microscope. The results show that, at the same cooling rate, with the decrease of the final cooling temperature, the number of bulk ferrite and granular bainite in the microstructure of the test steel decreases gradually, the number of lath bainite increases, the yield strength and tensile strength increase, and the elongation decreases.The excessive cooling rate and low final cooling temperature keep theinteraction between dislocations and dislocations, dislocations and grain boundaries in rolling process, and effectively improves the strength properties of the test steel. When the cooling rate is too big, the fracture dimples are elongated seriously, a few areas are quasi-cleavage, the resistance to crack growth becomes worse, and the toughness decreases.

关 键 词：超快速冷却工艺 高强度结构钢 组织 力学性能 板条贝氏体 

分 类 号：TG161[金属学及工艺—热处理] TG156.1[金属学及工艺—金属学]