喷射成形高钒钢复合轧辊修复及摩擦行为研究

It is a very important problem that how to repairing failure rolls in the roll manufacturing field. Although a lot of technologies were used in the field of rapairing rolls, there are many widespread problems，such as: coarse microstructure, thin thickness and low bonding strength. So this project intends to research how to repair the high vanadium steel composite roll by use of spray forming technology. The microstructure are considerably homogeneous and are comprised of small, equiaxed grains, due to increased capacity of heat extraction during spray forming solidification, showing no-macrosegregation, no obvious nonmetallic inclusions and pores. Firstly, spray forming process design and parameters were improved and optimized, such as: deposit machine movement mode, substrate heating mode and so on. Secondly, the characteristic of interface bonding between repair-layer and substrate were focused studied. The internal relationship between spray forming process and material microstructure and properties was explored, the effect of microstructure and carbide on frictional behavior and wear mechanism was expounded. At last, according to experiment parameters and the results of microstructures and performances, based on simulation by finite element method, the repairing of spray forming composite roll at the real working condition under complicated environment was predicted. The theory and technology on spray forming repairing composite roll for the engineering application were established.

如何修复失效轧辊一直是轧辊制造业面临的重大问题。目前虽然修复技术较多，但普遍存在修复组织粗大、修复层厚度较薄以及结合强度偏低等问题。因此，本项目拟采用喷射成形技术开展高钒钢复合轧辊修复实验研究，充分利用喷射成形快速凝固特点，获得组织细小、成分均匀、无明显宏观偏析的修复组织。首先，开展喷射成形工艺设计和改进优化，重点实现雾化锥和沉积器运动的有效耦合、改进沉积基体预热方式等；然后，重点研究修复层/基体的界面结合特征，揭示喷射成形工艺与材料组织性能的内在联系，阐明微观组织、碳化物特征对摩擦行为及磨损机制的影响规律。最后，根据实验工艺参数及组织性能结果，基于有限元模拟，对真实工况复杂环境下的喷射成形复合轧辊修复进行预测。为实现喷射成形复合轧辊修复的工程化应用奠定理论和技术基础。

如何设计最优化方案修复失效材料和部件，一直是再制造行业面临的重大问题。目前虽然修复技术较多，但普遍存在修复组织粗大、修复层厚度较薄以及结合强度偏低等问题。本项目采用喷射成形技术应用于材料修复领域，并对工艺方案进行了改进设计，实现雾化锥和沉积器运动的有效耦合、改进沉积基体预热方式。基于热力学、动力学模型，研究了喷射雾化液滴-介质交换温度变化规律及相演变特征，建立了基于热交换系数、润湿角、相变的耦合交互作用模型，揭示了不同热交换条件下液滴温度变化、凝固过程演变规律。运用相场法模拟不同边界热通量下枝晶生长行为，奠定喷射雾化合金液滴快速凝固控制理论。研究不同Ti、Co元素含量修复材料的晶粒尺寸、错配度、强化相尺寸及分布特征，探讨了影响因素对摩擦磨损性能的综合作用机制，建立了合金设计、凝固工艺制定、组织成分及性能调控的理论联系。

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