Abstract: With 50 kg vacuum induction furnace melted ingot,breakdown at 1150 ℃ and two stage control rolling, 12 mm plate finishing rolling at 830 ℃,then relaxation for 27 s,water cooling at 720 ℃ with cooling rate 30~35 ℃/s,  the   ultra-low-carbon   bainite   steel-0.023C,1.63Mn,0.52Cu,0.25Mo,0.055(Nb+Ti),0.0011B   had   compound   structure consisting of lath bainite + minor granular bainite,and irregular ferrite. The bainite bunch colony size was 3~5 μm  and the lump and irregular ferrite size was1~2.5 μm. Tempering at 650 ℃ and 700℃ weren't obvious influence on bainite grain orientation.

Key words: Ultra-Low-Carbon Bainite Steel,Equivalent Grain Diameter,Tempering

摘要： 用50kg真空感应炉冶炼的钢锭,经1150℃开轧,两阶段控制轧制,830℃终轧成12mm钢板,驰豫27s,720℃进水快冷(冷却速率30～35℃/s)后,超低碳贝氏体钢(成分%:0.023C、1.63Mn、0.52Cu、0.25Mo、0.055(Nb+Ti)、0.0011B)具有板条贝氏体+少量粒状贝氏体和不规则铁素体的复合组织,贝氏体束团尺寸为3～5μm,块状和不规则铁素体尺寸为1～2.5μm。650℃和700℃回火对贝氏体晶粒取向无显著影响。

关键词: 超低碳贝氏体钢, 等效晶粒直径 , 回火