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通过实验室热轧机组的控轧控冷试验,研究了控轧控冷参数对超高强铁素体/贝氏体双相钢组织性能的影响。结果表明,采用不同温度终轧,轧后不同方式冷却,抗拉强度几乎都在1 000MPa以上,屈强比在0.54～0.62之间,伸长率在13%～17%之间。铁素体晶粒随终轧温度降低和冷却速度加快而细化;终冷温度降低,贝氏体量增多。经800℃终轧后层流冷却至560℃左右空冷,由于铁素体晶粒细化,组织中大量的粒状贝氏体、无碳化物贝氏体、少量的孪晶马氏体以及残余奥氏体的存在使抗拉强度达1 130MPa,伸长率达16%,强塑积达到18 080MPa.%的最高值。控轧控冷获得以铁素体/贝氏体双相组织为主并含有少量残余奥氏体＋马氏体的复相组织,使试验钢具有了优异的力学性能。

Controlled rolling and cooling of ultra-high strength ferrite-bainite dual phase steel in the different conditions were conducted by a laboratory hot rolling mill.Effect of various processing parameters on the microstructure and mechanical properties of the steel was investigated.The results show that ultra-high strength dual phase steel with ferrite-bainite microstructure can be obtained by applying controlled rolling and cooling.The tensile strength values are nearly the same in all cases and always exceed 1 000 MPa,yield ratio varies from 0.54 to 0.62 and the total elongation varies from 13% to 17% for the specimens which are cooled at different cooling rates after various finish rolling temperatures.The ferrite grains are refined with decreasing finish rolling temperature and accelerating cooling,and the amount of bainite increases with decreasing finish cooling temperature.Tensile strength,total elongation and the product of tensile strength and total elongation for the specimen,which is finished rolling at 800 ℃ and subsequent laminar cooling to 560 ℃ and then air cooling to room temperature,reach maximum values（1 130 MPa,16% and 18 080 MPa%,respectively）.This is attributed to the ferrite-grain refinement,strengthening of granular bainite,carbide free bainite and a small amount of twinning martensite.The presence of retained austenite improves the ductility of the steel.Multiphase microstructures contain ferrite and bainite as main phase with a small amount of retained austenite and martensite,contribute to enhance mechanical properties of tested steel.