Abstract: For a steel factory production of BTW1 continuous casting slab is taken as the research object， and high temperature thermoplastic test is carried out by Gleeble 3800 thermal simulation testing machine.The tensile fracture is observed and the microstructure is analyzed by metallographic microscope and scanning electron microscope.The test results show that the reduction of area of BTW1 steel decreases first， then increases and again decreases with the increase of heating temperature. The reduction of area reaches the highest value of 68.3% at 1 000 ℃ and only 29.23% at 950 ℃. The reduction of area of BTW1 steel is lower than 40% in several temperature ranges， and the high temperature thermoplasticity is very poor， the crack sensitivity is strong.When the heating temperature is lower than 800 ℃， the thermoplasticity is poor due to the absence of MBIP and DRX， and the fracture morphology shows the coexistence of plastic deformation and brittle fracture. When the heating temperature is lower than 800 ℃， there is no microband induced plasticity and dynamic recrystallization， resulting in poor thermoplasticity， plastic deformation and brittle fracture coexist；When the heating temperature is 950 ℃， the DRX phenomenon increases， but the mixed crystal structure leads to a decrease in plasticity， and the fracture morphology is typical brittle fracture. When the heating temperature is 1 000 ℃， the DRX process is obvious， and the uniform fine grain region is formed， and the fracture is typical dimble morphology. When the heating temperature is 1 100 ℃， a melting zone appears in the fracture， but part of the dimpled structure remains at high temperature.

Key words: BTW1 Steel, Continuous Casting Slab, High Temperture Thermoplastic, Reduction of Area, Dynamic Recrystallization

摘要： 以某钢厂生产的BTW1钢连铸坯为研究对象，利用Gleeble 3800热模拟试验机开展高温拉伸试验，通过对拉伸断口进行观察，并利用金相显微镜和扫描电镜对组织进行分析。试验结果表明，BTW1钢断面收缩率随加热温度升高呈现先下降后上升再下降的趋势，断面收缩率在1 000 ℃时达到最高值68.3%，在950 ℃时仅为29.23%，BTW1钢断面收缩率在多个温度区间低于40%，高温热塑性极差，裂纹敏感性强。当加热温度低于800 ℃时，由于未发生微带诱导塑性和动态再结晶现象，导致热塑性较差，断口形貌呈现塑性变形和脆性断裂共存；当加热温度为950 ℃时，动态再结晶现象增加，但混晶组织导致塑性下降，断口形貌为典型的解理性脆断，当加热温度为1 000 ℃时，动态再结晶过程明显，形成均匀细小晶粒区域，塑性显著提升，断口为典型韧窝形貌；当加热温度为1 100 ℃时，断口出现熔化区域，但高温下仍保留部分韧窝结构。

关键词: BTW1钢, 连铸板坯, 高温热塑性, 断面收缩率, 动态再结晶