90 mm厚工程机械用Q460钢板热轧后的水冷工艺优化
Water-Cooling Process Optimization of Q460 Steel Plate with 90 mm Thickness for Construction Machinery after Hot-rolling
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摘要: 采用低碳和添加铌、钒、钛、铬等微合金元素的成分设计,利用洁净钢冶炼、奥氏体再结晶区粗轧、奥氏体未再结晶区精轧等工艺生产90 mm厚Q460钢板,热轧后采用大流量低辊速控制策略的1次水冷工艺和小流量间断开水控制策略的3次往复式水冷工艺进行水冷,研究不同水冷工艺对钢板组织和力学性能的影响,以获得合适的水冷工艺。结果表明：1次水冷工艺生产的试验钢板的显微组织主要为针状铁素体+少量珠光体,3次往复式水冷工艺生产的试验钢板的显微组织主要为多边形铁素体+珠光体+少量粒状贝氏体；与3次往复式水冷工艺相比,1次水冷工艺生产的试验钢板厚度方向的组织更加均匀、细小,且形成了针状铁素体。2种水冷工艺生产的试验钢板的拉伸性能和冲击韧性均满足标准要求,但是1次水冷工艺生产的试验钢板的−40 ℃冲击韧性明显优于3次往复式水冷工艺生产的试验钢板,且厚度方向的冲击韧性更均匀。90 mm厚Q460钢板热轧后的合适水冷工艺为1次水冷工艺,所得钢板的屈服强度为495~512 MPa,抗拉强度为604~616 MPa,断后伸长率23%~24%,−40 ℃冲击吸收功为200 J以上。Abstract: The 90 mm thick Q460 steel plates were produced by clean steel smelting, rough rolling in austenite recrystallization zone and fine rolling in austenite non-recrystallization zone with the composition design of low carbon and adding micro-alloying elements such as niobium, vanadium, titanium and chromium. The steel plates were water-cooled by one-time water-cooling process with large flow and low roll speed control strategy and three-time reciprocating water-cooling process with small flow and intermittent water control strategy after hot-rolling. The effects of different water-cooling processes on the microstructure and mechanical properties of steel plates were studied in order to obtain suitable water-cooling process. The results show that the microstructure of the test steel plate produced by one-time water-cooling process was mainly acicular ferrite + a small amount of pearlite, while that of the test steel plate produced by three-time reciprocating water-cooling process was mainly polygonal ferrite + pearlite + a small amount of granular bainite. Compared with that by three-time reciprocating water-cooling process, the microstructure in thickness direction of the test steel plate produced by one-time water-cooling process was more uniform and finer, and acicular ferrite was formed. The tensile properties and impact toughness of the test steel plates produced by the two kinds of water-cooling processes met the standard requirements, but the impact toughness of the test steel plate produced by one-time water-cooling process was significantly better than that produced by three-time reciprocating water-cooling process at −40 ℃, and the impact toughness in the thickness direction was more uniform. The suitable water-cooling process for Q460 steel plate with a thickness of 90 mm after hot-rolling was one-time water-cooling process, and the steel plate had the yield strength of 495–512 MPa, tensile strength of 604–616 MPa, percentage elongation after fracture of 23%–24%, and impact absorption energy of more than 200 J at −40 ℃.
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