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“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。
“Topography Self-Healing Effect ” is an important phenomenon that may appear in the direct laser metal forming process. Depending on the adjustment of the process parameters during the deposition process, it is possible to control the possible bump Uneven state regained to flat state. In the “hollow laser, light powder feeding” new method, by adjusting the ring laser defocus amount can produce significant melting bump defects self-healing effect. The relationship between the laser defocusing amount and the thickness of the single layer is theoretically analyzed. The relationship between the laser defocusing amount and the height of the single layer cladding is obtained. On the 304 stainless steel substrate with “ The wall thickness, microstructure and microhardness of thin walled wall were analyzed by vernier caliper, SEM and microhardness tester. The results show that different laser defocusing amounts have a significant effect on the self-healing ability of the topography. When the defocus amount is 0 ~ -3 mm, the original irregularity of the thin wall appearance And does not appear; when the defocus amount is -3 mm ~ -5 mm, the unevenness of the thin-walled wall appearance is gradually repaired with the increase of the number of layers, and the surface of the several layers is smooth and flat, and the phenomenon of ”self-healing" It is verified that the thin wall repaired by self-healing has a small change in width, good metallurgical bonding with the matrix, dense and uniform structure, and a slowly decreasing trend from the top of the wall to the base.