通过硬度测试、X射线衍射分析、有限元模拟以及TEM微观组织观察等手段研究了大规格B93铝合金棒材的淬透性。研究结果表明,淬火后,越靠近棒材中心,晶内和晶界析出的平衡相(MgZn2)数量越多,尺寸越大,120℃/24h时效后的强化效果就越低;而棒材表面则处于完全固溶状态,组织均匀,时效后析出大量细小弥散的η’沉淀相,合金的硬度最高。棒材的淬透层深度为30mm左右,临界淬火冷却速率为15℃/s。
Abstract
The quench sensitivity of the Al-Zn-Mg-Cu alloy for large sized bars were studied by means of hardness test,X-ray diffraction analysis,finite element simulation and microstructure observation.The results show that,the closer to the centre of the quenching bars,the larger quantities of equilibrium MgZn2 are observed in the grain inner and on the grain boundary and keep growing up.And small quantity of hardening precipitates are exhibited in the 120℃/24h aging samples.It results in the decline of the age-hardening effect.For the surface of the bar,the second phase was not observed and the homogeneous content in the grain inner was obtained,which may attribute to the super saturated solid solution.A number of η′dispersoid were found at the surface.The dispersive phases are able to promote the precipitation strengthening effect and the hardness of the alloy reach the peak.The value of the quenching depth is 30mm,and the critical quench cooling rate is 15℃/s.
关键词
B93铝合金 /
淬透层深度 /
淬透性 /
微观组织
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Key words
B93 aluminum alloy /
the depth of quenchi /
quench sensitivity /
microstructure
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脚注
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基金
国际科技合作重点项目(2006DFA53240)
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