Abstract: The flowsheet of 236 mm x 1 350 mm casting slab of tested steel CR1030/1300MS (/% : 0. 13C, 0. 26Si, L53Mn, 0.011P, 0.002S, 0.31Cr, 0.047Als, 0.029Nb, 0.032Ti, 0.002 5B, 0.003 2N) is 260 t BOF-LF-RH-CC process. With using Gleeble3500 thermal simulation test machine the thermoplasticity curves of test slab at 650 ~ 1 300 °C has been measured and the structure of high temperature tensile specimen fracture is analyzed. The test results obtain that the two brittle zones in test steel are melting point 〜1 120 °C and 800 〜650 °C , and the better plasticity occurs at 1 120 ~ 800 °C , in this zone the reduction of area of steel is more than 85%. The fracture of tensile of steel at 900 °C. is transgranular toughness fracture and at 700 °C it is toughness and along crystal fracture. The structure near fracture of tensile of steel at 1 250 °C and 900 °C is martensite and with increasing temperature the martensite lath is coarser. The basic reason to form crack is that the proeutectoid ferrite occurs in original austenite grain boundary at 750 °C.Straightening at 1 120 ~ 800 °C is available to avoid the casting bloom forming crack.

摘要： 试验用CR1030/1300MS钢236 mm×1 350 mm连铸板坯(/%:0.13C,0.26Si,1.53Mn,0.011P,0.002S,0.31Cr,0.047Als,0.029Nb,0.032Ti,0.002 5B,0.003 2N)的工艺流程为260 t BOF-LF-RH-CC。采用Gleeble3500热模拟试验机测试了试验板坯650～1 300℃的热塑性曲线,并分析了高温拉伸试样断口组织。试验结果得出,试验钢两个脆性区为熔点～1 120℃和800～650℃在1 120-800℃呈现良好的塑性,断面收缩率均在85%以上。900℃断口属于穿晶韧性断裂,700℃为韧性和沿晶断裂。1 250℃和900℃近断口组织均为马氏体,温度升高马氏体板条更粗大。750℃原奥氏体晶界出现先共析铁素体是产生裂纹的根本原因。1 120～800℃进行矫直可防止铸坯产生裂纹。

关键词: 高强度钢CR1030/1300MS 236 mm x 1 350 mm连铸板坯, 热塑性, 断口分析