中空环形激光离焦量对熔道凹凸缺陷自愈合效应的影响

发布时间：2018-04-27 12:14

本文选题：激光技术 + 激光立体成形　；参考：《中国激光》2015年05期

【摘要】："形貌自愈合效应"是激光金属直接成形过程中可能出现的一个重要现象,在堆积过程中依靠自身工艺参数的调整,可以控制多层堆积的熔道从堆积表面可能出现的凹凸不平状态重新恢复到平整状态。在"中空激光、光内送粉"新工艺的方法下,通过调整环形激光离焦量能产生明显的熔道凹凸缺陷的自愈合效应。对激光离焦量与单层堆积厚度影响规律进行了理论分析,获得激光离焦量与单层熔覆高度的关系曲线,并在具有"栅栏凸起"的304不锈钢基板上堆积多组薄壁墙试样进行试验验证,同时利用游标卡尺、扫描电镜及显微硬度计对愈合完好的薄壁墙的宽度、微观组织及显微硬度进行了分析。结果表明,不同的激光离焦量对其形貌自愈合能力影响显著,当离焦量为0~-3 mm时,薄壁墙形貌原有的起伏不平"自愈合现象"并不会出现;当离焦量为-3 mm~-5 mm时,薄壁墙形貌的起伏不平随层数增加被逐渐修复,若干层后表面光滑平整,"自愈合现象"得到验证;通过自愈合修复的薄壁墙,宽度变化很小,与基体冶金结合良好,组织致密均匀,从墙顶至基体硬度值呈缓慢下降趋势。
[Abstract]:The "self-healing effect of morphology" is an important phenomenon that may occur in the process of direct laser metal forming, which depends on the adjustment of its own technological parameters in the process of stacking. The multilayer stacking fuse can be controlled to recover from the uneven state of the stacked surface. Under the new technology of "hollow laser, optical powder feeding", the self-healing effect of the concave and convex defects of the melting channel can be obviously produced by adjusting the defocus of the ring laser. The relationship between laser defocusing and cladding height is obtained by theoretical analysis of the influence of laser defocusing amount and single layer stacking thickness. At the same time, several groups of thin-walled wall specimens were accumulated on the 304 stainless steel substrate with "palisade bulge". At the same time, the width of the well-healed thin-walled wall was obtained by using Vernier caliper, scanning electron microscope and microhardness meter. Microstructure and microhardness were analyzed. The results show that the self-healing ability of the thin-walled wall is affected by different laser defocusing amount. When the defocusing amount is 0 ~ 3 mm, the original "self-healing" phenomenon of thin-walled wall will not appear, and when the defocusing amount is 3 ~ 3 mm~-5 mm, the original "self-healing" phenomenon of thin-walled wall will not occur. The uneven appearance of thin-walled wall was gradually repaired with the increase of the number of layers, the surface of several layers was smooth and smooth, the phenomenon of "self-healing" was verified, the width of thin-walled wall repaired by self-healing was very small, and the thickness of thin-walled wall was well combined with matrix metallurgy. The microstructures are compact and uniform, and the hardness values from the top of the wall to the matrix decrease slowly.
【作者单位】：苏州大学机电工程学院;
【基金】：国家自然科学基金(61475107,11172191)
【分类号】：TG665

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