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含钒钛微合金钢连铸板坯因表面裂纹严重影响铸坯质量,这与其在连铸过程中的热塑性密切相关。以攀钢目前生产的含钒钛微合金钢为研究对象,研究了从熔点到550℃温度范围内热塑性的变化规律。采用数理分析方法,首次建立了含钒钛微合金钢的流变模型。用此模型预测含钒钛微合金钢在连铸条件下的热塑性,并作为改进连铸工艺的依据之一。在研究含钒钛微合金钢连铸板坯的表面裂纹与热塑性的关系时,发现连铸板坯表面横裂纹往往在振痕谷部产生。据此开创性地用高温下的非连续模型热拉伸实验模拟铸坯表面横裂纹的产生过程。结果表明,振痕产生的应力集中降低了含钒钛微合金钢的热塑性。论文把高温时应力集中导致材料热塑性变化称为材料的高温应力集中敏感性,并用高温应力集中敏感参数τ=(RA-RA′)/RA×100％来描述(RA是连续模型断面收缩率;RA′是非连续模型断面收缩率)。根据这一定义。采用数理分析方法定量研究了含钒钛微合金钢从熔点到700℃温度范围内高温应力集中敏感性的变化规律,并建立了高温应力集中敏感性模型。通过此模型,可预测含钒钛微合金钢在连铸过程中的高温应力集中敏感性,并对由流变模型得到的连铸工艺参数进行调整。采用理论计算和实验手段研究了钒钛在钢中的存在状态及其对热塑性和高温应力集中敏感
The vanadium-titanium microalloyed steel continuous casting slab seriously affects the slab quality due to surface cracks, which is closely related to its thermoplasticity in the continuous casting process. Taking the present vanadium-containing titanium microalloyed steel produced in Panzhihua Iron and Steel Co., Ltd. as the research object, the change rule of the thermoplasticity in the temperature range from the melting point to 550 ℃ was studied. Using the method of mathematical analysis, the rheological model of vanadium-titanium microalloyed steel was established for the first time. This model is used to predict the thermoplasticity of vanadium-bearing titanium microalloyed steel under continuous casting and as a basis for improving the continuous casting process. In the study of vanadium-bearing titanium microalloyed steel continuous casting slab surface cracking and thermoplastic relationship, found that continuous casting slab surface cracks often occur in the vibration valley. Based on this, the hot stretch experiment of discontinuous model at high temperature was used to simulate the generation of transverse crack on slab surface. The results show that the stress concentration caused by the vibration marks reduces the thermoplasticity of vanadium-titanium microalloyed steels. In this paper, the thermal stress concentration induced by the stress concentration at high temperature is called the high temperature stress concentration sensitivity of the material and is described by the parameter RA = RA-RA ’/ RA × 100% (RA is the reduction of area of the continuous model; RA ’is the discontinuous model section shrinkage). According to this definition. Mathematical analysis was used to quantitatively study the variation of high-temperature stress concentration sensitivity of vanadium-titanium microalloyed steel from the melting point to 700 ℃ and to establish a model of high temperature stress concentration sensitivity. Through this model, the high temperature stress concentration sensitivity of the vanadium-bearing titanium microalloyed steel in the continuous casting process can be predicted and the continuous casting process parameters obtained from the rheological model can be adjusted. The existence of vanadium-titanium in steel and its sensitivity to the thermomechanical and high-temperature stress concentration have been studied theoretically and experimentally