中碳V、Ti微合金钢连轧圆坯表面裂纹的研究

Study on Surface Cracks of Continuous Rolling Round Billet of V-Ti-added Medium Carbon Micro-alloyed Steel

为了减少中碳V、Ti微合金钢连轧圆坯的表面裂纹，在实验室条件下，测定了中碳V、Ti微合金钢的高温塑性和脆性温度范围，分析了影响中碳V、Ti微合金钢铸坯、连轧圆坯表面裂纹的因素，确认在900～820％温度范围内，随温度的下降，钢中V、Ti氮化物和碳氮化物在奥氏体晶界大量析出，弱化了晶界的变形能力，是造成中碳V、Ti微合金钢连轧圆坯表面裂纹的主要原因。结合实际生产过程，对现行生产工艺提出了改进建议。

In order to reduce surface cracks of continuous roiling round billet of V - Ti - added medium carbon micro- alloyed steel, the temperature ranges on plasticity at high temperature and brittleness of the said steel are measured and influencing factors that affect the surface cracks of strands and continuous rolling round billets are analyzed under laboratory conditions. It is concluded that numerous vanadium nitride, titanium nitride and carbonitride in the steel precipitate at the aus- tenite boundary so much that the deformability at the boundary is weakened as the temperature de- creases within the ranges of temperatures from 900 to 820~C. This weaking is the main cause for leading surface cracks of continuous rolling round billets of V - Ti - added medium carbon micro - alloyed steel. Suggestions on improving the existent manufacturing technology are proposed based on the actual operations during production process.