【摘要】 对780MPa级工程机械用钢进行了现场批量生产试制,对其组织与性能进行了研究.通过合理的成分设计,采用控制轧制和超快冷+层流冷却的两阶段冷却路径控制,获得了良好的组织与性能.结果表明:终轧后采用超快冷+层流冷却工艺,超快冷的出口温度在650℃,卷取温度在570℃,试验钢的屈服强度大于685 MPa,抗拉强度大于785 MPa,并具有良好的冲击性能、成形性能及焊接性能.试验钢的组织为铁素体+少量珠光体,同时,在铁素体的基体上,存在大量10nm左右的弥散析出或相间析出(Nb,Ti)(C,N),有效提高了试验钢的强度.更多还原

【Abstract】 A mass trial was carried out for a 780 MPa engineering machinery steel and the microstructures and properties of steel were investigated.The controlled rolling,ultra-fast cooling and laminar cooling process were used based on the optimized compositions of steel,and good microstructures and mechanical properties were obtained.The results showed that ultra fast cooling plus laminar cooling process is used after the finish rolling,and the outlet temperature of ultra fast cooling and coiling temperature are controlled at 650 ℃ and 570 ℃,respectively.The yield and tensile strengths of steels are higher than 685 MPa and 785 MPa,respectively,and good impact resistance,formability and weldability are obtained.The microstructures of steels are composed with ferrite and a litlle of pearlite.A large number of(Nb,Ti)(C,N) precipitates are observed with size less than 10 nm dispersed in the ferrite matrix,and these fine precipitates increase the strength of steel effectively.更多还原