ISSN   1004-0595

CN  62-1224/O4

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T6处理对选区激光熔化AlSi10Mg微观组织和磨损性能的影响

Effect of T6 Treatment on Microstructure and Wear Properties of AlSi10Mg by Selective Laser Melting

  • 摘要: 选区激光熔化(SLM)技术是制造业发展的重要方向,AlSi10Mg是SLM领域应用最广泛的铝合金材料. T6(固溶+时效)热处理可以有效提高材料服役性能,但T6热处理对SLM-AlSi10Mg磨损行为的影响机制仍不清楚. 本研究中对比分析了6、9、12以及15 N载荷下去应力态(SR)和SR+T6态SLM-AlSi10Mg的干滑动摩擦磨损行为. 研究表明:T6处理对AlSi相微观结构的影响最大,AlSi相的体积分数和平均尺寸由SR态的11.4%和1.28±0.02 μm分别增加至SR+T6态的15.5%和2.13±0.06 μm,但密度由SR态的0.084个/μm2减小至SR+T6态0.040个/μm2;弥散强化及固溶强化效应的削弱使得硬度由SR态的104.5HV降低至SR+T6态的86.6HV;不同载荷下SR+T6态的耐磨性能较SR态均显著提升,但存在不同作用机理,由于载荷的增加加剧了磨痕亚表面疲劳裂纹的萌生及扩展,主要磨损机制由低载荷(6 N)下的显微切削转变为高载荷(9、12和15 N)下的疲劳剥落,低载荷(6 N)下,AlSi相尺寸的增加使SR+T6态的耐磨损性能较SR态提升了约40%,高载荷(9、12和15 N)下,弥散分布的AlSi相加速了由纳米晶粒构成的摩擦转变组织(Tribology transformation structure, TTS)层的形成,进而加剧疲劳裂纹的形成;AlSi相密度的降低使SR+T6态的耐磨损性能较SR态提升了约30%~35%.

     

    Abstract: Selective laser melting (SLM) technology is an important development in manufacturing. AlSi10Mg is the most widely used aluminum alloy material in the field of SLM. Numerous service properties of the material have been proven to be effectively improved by the T6 (solution + aging) heat treatment, but the effect of T6 heat treatment on the wear behavior of SLM-AlSi10Mg remains unclear. In this study, the dry sliding wear behaviors of stress relieved (SR) and SR+T6 treated SLM-AlSi10Mg at 6, 9, 12 and 15 N were comparatively researched. The results indicated that the microstructure of AlSi precipitates was most affected by the T6 treatment. The volume fraction and average size of the AlSi precipitates increased from 11.4% and 1.28 ± 0.02 μm in the SR treated SLM-AlSi10Mg to 15.5% and 2.13±0.06 μm in the SR+T6 treated SLM-AlSi10Mg, respectively, but its density decreased from 0.084 per square micron of SR treated SLM-AlSi10Mg to 0.040 per square micron of SR+T6 treatedSLM-AlSi10Mg. The weakening of the diffusion strengthening and solid solution strengthening effects reduced the hardness from 104.5HV of SR treated SLM-AlSi10Mg to 86.6HV of SR+T6 treated SLM-AlSi10Mg. The wear resistance of the SR+T6 treated SLM-AlSi10Mg was significantly higher than that of the SR treated SLM-AlSi10Mg at different loading, but with different influencing mechanisms. The increase in loading exacerbated the initiation and propagation of fatigue cracks in the worn subsurface, resulting in a transformation of the main wear mechanism from the micro-cutting (loading of 6 N) to the fatigue spalling (loading of 9, 12 and 15 N). Under the condition of low loading (6 N), the wear resistance of the SR+T6 treated SLM-AlSi10Mg was improved by about 40% compared to the SR treated SLM-AlSi10Mg for the increasing size of AlSi phase. Under the condition of high loading (9, 12 and 15N), the diffusely distributed AlSi precipitates accelerated the formation of the tribology transformed structure (TTS) composed of nano-grains, which in turn aggravated the formation of fatigue crack. As a result, the reduction of AlSi phase density improved the wear resistance of the SR+T6 treated SLM-AlSi10Mg by about 30%~35% compared with the SR treated SLM-AlSi10Mg.

     

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