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 ℃.
关键词
厚规格Q460钢板/热轧后的水冷工艺/拉伸性能/低温冲击韧性
Key words
thick specification Q460 steel/water cooling process after hot-rolling/tensile property/low temperature impact toughness
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