激光熔化沉积AlSi10Mg成形特性及力学性能

Formability and Mechanical Property of Laser Metal Deposited AlSi10Mg Alloy

目的研究激光熔化沉积Al Si10Mg铝合金的成形特性及力学性能。方法以颗粒度45~105μm的Al Si10Mg粉末为材料,6061铝合金为基板,利用光纤激光器在充氩舱内分别进行单层单道、竖直薄壁单墙体与倾斜薄壁墙体的成形试验。测试单墙体的抗拉强度与延伸率,并通过扫描电子显微镜和光学显微镜对微观组织形貌进行分析。结果单层单道沉积层高度与激光扫描速度负相关,与送粉速度成线性正相关;而沉积层宽度与扫描速度负相关,与激光功率正相关。沉积单墙体时,沉积前10层最不稳定,墙体厚度低于后续层的厚度。为了使沉积过程稳定,墙体不塌陷,通过激光功率在前20层左右逐层递减,成功制备出250层(高10cm)以上的单墙体。工艺选取合适时,AlSi10Mg具有良好的成形能力,激光头角度保持竖直不变,墙体倾角60°以下可以稳定沉积。制备沉积态Al Si10Mg气孔率约3%,抗拉强度250MPa左右,延伸率5%以上,抗拉强度高于成分相似的ZL104铸件25%。微观组织内Al-Si共晶细小,没有针片状共晶组织,并且组织沿沉积方向呈现周期性变化。结论 Al Si10Mg在激光熔化沉积时具有良好的成形能力,沉积态的组织强度高于铸态组织强度。优化后的工艺可以稳定沉积制备下圆上方的变截面薄壁样件。

The work aims to study the formability and mechanical property of laser metal deposited AlSi10Mg alloy. AlSi10Mg powder with size ranging from 45 to 105 μm was utilized as the material and 6061 aluminum alloy was used as the substrate. Single-layer cladding, thin walls and inclined walls were manufactured with fiber laser in argon chamber to test the formability. The tensile strength and elongation of the walls were tested. The microstructure was analyzed with optical microscope and SEM. There was a positive correlation between the height of single layer and powder feeding speed, but a negative correlation with the scanning speed. Further, the same correlation also existed between the width of single layer and laser power and between the width and the scanning speed. When single-layer wall was deposited, the first 10 layers were not stable. The thickness of wall was thinner than subsequent layers. For the sake of improving the stability and preventing from collapse of walls, laser power should decline gradually in the first 20 layers. With this method, a wall more than 250 layers was made steadily and successfully. AlSi10Mg had good formability when process parameters were selected properly. Inclined walls could be deposited even if the wall had tilted to 60 degree. The porosity of the walls was nearly 3%. The tensile strength was approximately 250 MPa and the elongation was about 5%. The tensile strength was 25% higher than that of ZL104 as-casted aluminum alloy. The microstructure periodically varied along the deposition direction. The eutectic was small and no needle-like eutectic was found. The AlSi10Mg has good formability in laser metal deposition process. The microstructure strength of as-deposited samples is better than as-casted alloy. Finally, a variable cross-section thin-walled sample is deposited with optimized processing parameters.