Inconel 738合金选区激光熔化成形工艺优化及组织性能的研究

Investigation on Selective Laser Melting Processing Optimization and Microstructure and Property of Inconel 738 Alloy

摘要:

采用SEM、EBSD、OM等方法,研究了激光体能量密度E对SLM成形Inconel 738合金致密度、微观组织和显微硬度影响。研究表明：在SLM成形过程中,激光体能量密度E对试样致密度起决定性作用,随着激光体能量密度的增大,致密度呈现先上升后下降的趋势,并且在65.2 J/mm<sub>3</sub>可以实现最高致密度(99.4％)；凝固过程中冷却速率高达2.44×10<sub>5</sub> K/s,SLM成形Inconel 738合金的组织垂直与打印方向和平行与打印方向有明显的各向异性,平行于打印方向的组织呈“棋盘状”形貌,垂直与打印方向为“鱼鳞状”形貌,层与层之间、不同道次之间的熔池搭接区为晶粒细化的胞晶；显微组织表现出明显的织构,随着激光体能量密度的增大,＜001＞方向的织构逐渐增强；试样的硬度随着激光体能量密度的增大而增大,当硬度值超过65.2 J/mm<sub>3</sub>时,SLM成形Inconel 738合金的硬度值超过精铸试样(410 HV),硬度值在各个面上的分布是定向独立的。

Abstract:

The effect of volume energy density on the relative density, microstructure and microhardness of Inconel 738 alloy fabricated by SLM was investigated by methods like SEM、 EBSD and OM. The results show that volume energy density the plays a decisive role in the SLM forming process. With the increase of the volume energy density, the relative density increases first and then decreases. The highest relative density (99.4%) can be achieved at 65.2J/mm3. During solidification, the microstructure of Inconel 738 alloy formed by 2.44×105 K/s SLM has obvious anisotropy in vertical direction and parallel direction. The microstructure parallel to the print direction is "chess board", the vertical to print direction is "fish scale", the overlap zone between layers and different tracks is the refined cellar grains. And the microstructure shows obvious texture, with the increase of the laser body energy density, the texture in the < 001 > direction increases gradually.The hardness of the sample increases with the increase of the laser body energy density. When the hardness value is higher than 65.2J/mm3, the hardness value of Inconel 738 alloy is higher than that of precision casting specimen (410 HV), hardness value is distributed on each surface independently.