二冷区温度波动下含Nb-Ti微合金钢热塑性行为研究

发布时间：2018-02-13 07:49

本文关键词： 微合金钢温度波动热塑性析出物铁素体　出处：《热加工工艺》2016年22期 　论文类型：期刊论文

【摘要】：基于国内某厂二冷区温度波动的实际生产工艺,利用Gleeble-3500热模拟试验机对温度波动下的Nb-Ti微合金钢进行拉伸测试。采用扫描电镜、光学显微镜对试样断口形貌及组织进行观察。结果表明:随温度波动幅度(ΔT)增大,铸坯脆性区右移。ΔT每升高25K,脆性区温度提高50 K左右。低温时,铸坯塑性几乎不随温度波动幅度变化而变化。随拉伸温度降低,试样断口由穿晶断裂开始向沿晶断裂转变。基体及韧窝底部存在夹杂物或第二相粒子,为空穴形核提供条件,成为恶化铸坯塑性的重要因素。随温度下降,铁素体逐渐形成。在相同测试温度下,温度波动越大对铁素体含量的影响更加明显。铁素体体积分数为36%时,该钢的热塑性达到最低值。
[Abstract]:Based on the actual production process of temperature fluctuation in secondary cooling zone of a domestic factory, the tensile test of Nb-Ti microalloyed steel under temperature fluctuation was carried out by using Gleeble-3500 thermal simulator. The fracture morphology and microstructure of the specimens were observed by optical microscope. The results showed that the brittle zone shifted to the right with the increase of temperature fluctuation amplitude (螖 T). With the increase of 螖 T by 25 K, the temperature of brittle zone increased about 50 K. at low temperature. With the decrease of tensile temperature, the fracture of the billet changed from transgranular fracture to intergranular fracture. There were inclusions or second phase particles at the bottom of the matrix and dimple, which provided the condition for the cavitation nucleation. It becomes an important factor to worsen the plasticity of billet. With the decrease of temperature, ferrite gradually forms. At the same test temperature, the effect of temperature fluctuation on ferrite content is more obvious. When the volume fraction of ferrite is 36, The thermoplasticity of the steel reaches the lowest value.
【作者单位】：华北理工大学冶金与能源学院;
【基金】：河北省自然科学基金(E2013209234)
【分类号】：TG142.1

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