TC17钛合金激光冲击温强化机制的研究

目的提高材料在交变载荷和高温下的疲劳性能,稳定材料的位错结构,增加位错的钉扎效果,使激光诱导的残余压应力更加稳定,有效地抑制强化效果的高温失稳。方法通过提高温度发生动态应变时效(DSA),并与激光冲击温强化(WLSP)结合,使得材料表面形成更深的残余应力层和纳米级沉淀相。对TC17钛合金温控激光冲击强化后的显微硬度、残余应力等性能进行了初步探索。结果经200℃的WLSP后,TC17钛合金的显微硬度可达385HV,相比未强化时提高了18.48%,相比于室温的LSP提高了4.62%。深度方向的残余压应力幅值呈现先增大后减小的趋势,200℃时残余应力达到-236 MPa,相比于常温强化提高了14.56%。观察微观组织发现,位错结构的稳定性和位错密度得到提高。结论激光冲击温强化(WLSP)技术提高了材料表面残余压应力层的高温稳定性,有利于抑制疲劳裂纹的萌生和扩展,有效地提高了高温条件下残余应力和表面强度的稳定性。该技术操作相对简单,无污染,残余应力高温维稳效果显著。     

Hybrid modelling of aluminium–magnesium alloys during thermomechanical processing in terms of physically-based,neuro-fuzzy and finite element models

For modern metals industries using thermomechanical processing, off-line modelling and on-line control based on physical knowledge are highly desirable in order to improve the quality of existing materials, the time and cost efficiency, and to develop new materials. Neural network and neuro-fuzzy models are the most popular tools, but they do not embed physical knowledge. On the other hand, current physically-based models are too complex for industrial application and are less efficient than neural networks. A combination of neuro-fuzzy and physically-based models has therefore been developed, which is termed a “hybrid model”. The hybrid model has been applied to predict flow stress and microstructural evolution during thermomechanical processing. Comparison with experimental data shows generally good agreement for Al–1% Mg alloy deformed under thermomechanical processing conditions. The hybrid model was then embedded into a finite element model and the simulated results show a very similar distribution to those calculated using empirical models.