铜基镍镀层双金属试样高温热疲劳损伤机理研究

发布时间：2018-08-05 15:07

【摘要】：随着钢铁冶炼技术的发展,轧制成为带钢生产中主要的生产工艺。其中主要包括冷轧、热轧以及双辊薄带连铸,所得产品的晶粒得到细化,组织性能较好,连铸连轧的生产方式如今已成为钢铁生产领域最为先进的的生产方式。轧辊是轧制工艺的核心部件,在热轧以及双辊薄带连铸的实际生产过程中,结晶辊辊需承受复杂多变的高温及应力载荷。轧辊除了正常的摩擦磨损失效,其主要的失效形式是轧辊工作面产生疲劳裂纹,疲劳失效是实际生产中轧辊主要的失效形式。由于轧辊的价格成本较高,因此延长轧辊的使用寿命,准确预测其疲劳失效规律,对于提升产品质量和性能以及降低生产成本具有重要意义。通过分析国内外学者所做的相关研究,归纳了对轧辊疲劳裂纹的产生和扩展有着重影响的诸多因素。根据双辊薄带铸轧实际生产过程中结晶辊出现的热疲劳失效问题,自行设计制作了热疲劳失效实验装置。通过实验的方法研究了,在一定载荷下,不同温度梯度对疲劳裂纹扩展的影响;不同的加热、冷却频率对热疲劳裂纹扩展的影响;有无镍镀层对基体热疲劳裂纹扩展的影响;在高温循环加热条件下,基体疲劳裂纹萌生及扩展机理。通过分析得到,在施加一定载荷作用下,随着加热温度的升高,内部交变热应力增大,铜基体的热疲劳裂纹前期扩展加快;当接触加热时间延长时,处于最大热应力状态时间增加,裂纹扩展初期较快,随着裂纹扩展尖端应力得到释放,裂纹扩展速率下降明显;镍镀层具有一定的阻热性,带有镍镀层的铜基体热疲劳裂纹的扩展长度略低于无镍镀层时铜基体的热疲劳裂纹扩展;高温条件下,裂纹尖端大量金属氧化物加速了疲劳裂纹的扩展。
[Abstract]:With the development of iron and steel smelting technology, rolling has become the main production process in strip steel production. It mainly includes cold rolling, hot rolling and double roll strip continuous casting. The grain size of the product is refined and the structure and properties are better. The production mode of continuous casting and rolling has become the most advanced mode of production in the field of iron and steel production. Roll is the core part of rolling process. In the process of hot rolling and double roll thin strip continuous casting, the crystal roll has to bear complex high temperature and stress load. In addition to the normal friction and wear failure, the main failure form of roll is fatigue crack in roll face, and fatigue failure is the main failure form of roll in actual production. Because of the high price and cost of roller, it is very important to prolong the service life of roller and accurately predict its fatigue failure law to improve the quality and performance of product and reduce the production cost. By analyzing the relevant research done by scholars at home and abroad, many factors which have important influence on the production and propagation of roll fatigue cracks are summarized. According to the thermal fatigue failure of the crystal roll in the production process of twin-roll thin strip casting, a thermal fatigue failure test device was designed and manufactured by ourselves. The effects of different temperature gradients on fatigue crack propagation, different heating and cooling frequency on thermal fatigue crack propagation, and the effect of nickel coating on thermal fatigue crack growth of substrate were studied by experimental method. The fatigue crack initiation and propagation mechanism of matrix under high temperature cyclic heating condition. Through analysis, under certain load, with the increase of heating temperature, the internal alternating thermal stress increases, the thermal fatigue crack Prophase growth of copper matrix is accelerated, and when the contact heating time is prolonged, In the state of maximum thermal stress, the initial stage of crack growth is faster, and the crack growth rate decreases obviously with the release of crack tip stress, and the nickel coating has a certain thermal resistance. The thermal fatigue crack propagation length of copper substrate with nickel coating is slightly lower than that of copper substrate without nickel coating, and the fatigue crack propagation is accelerated by a large number of metal oxides at the crack tip at high temperature.
【学位授予单位】：山东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG333.17

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