工艺参数对316L不锈钢激光熔覆层中Cr元素分布的影响

Effects of Process Parameters upon Chromium Element Distribution in Laser-Cladded 316L Stainless Steel

采用基于体积平均法的气-固-液三相激光熔覆模型,探究了工艺参数对45钢表面激光熔覆316L不锈钢熔覆层中Cr元素分布及其均匀性的影响。首先,使用Cr元素的平均浓度来表征熔覆层中元素的分布情况,并对熔覆过程中Cr元素分布的演变进行分析;然后,将Cr元素在y方向分布的计算结果与实验结果进行对比,验证了模型的可靠性;之后通过设定的正交工艺参数进行模拟,探究工艺参数与熔覆层中Cr元素平均含量之间的关系;最后,根据模拟结果对熔池的流动行为进行分析,探究工艺参数与熔覆层中Cr元素在x方向分布均匀性之间的关系。研究结果表明:对熔覆层中Cr元素含量影响最大的工艺参数是送粉率,然后依次为激光功率和扫描速度,送粉率与Cr元素含量呈正相关,激光功率与Cr元素含量呈负相关。熔池凝固速率与流速对熔覆层中Cr元素分布的均匀性有较大影响,可通过适当增大激光功率和降低扫描速度来获得元素分布更为均匀的熔覆层。

The gas-solid-liquid three-phase model based on the volume-average method was used to study the influence of process parameters upon the chromium element distribution and its uniformity in laser-cladded 316 L stainless steel on 45 steel. First, the chromium elemental distribution in cladding layer was characterized by average concentration of chromium element and the evolution of chromium element distribution during the cladding process was analyzed;secondly, the simulated and experimental Cr distributions along y direction were compared to verify the model′s reliability. Then, a simulation was performed by set the orthogonal-process parameters to obtain the relationship between the process parameters and the distribution of chromium element in the cladding layer. Finally, according to the simulation results, the flow behavior of the molten pool was analyzed to obtain the relationship between the process parameters and the uniformity of chromium element in the cladding layer along the x direction. The result shows that the powder-feeding rate has the greatest influence on chromium content in the cladding layer, followed by laser power and scanning speed in sequence. The powder-feeding rate is positively related to the average concentration of Cr, whereas the laser power is negatively related to this concentration. The solidification and flow rates of the molten pool have an important impact upon the uniformity of the chromium element distribution in the cladding layer. A cladding layer with a more uniform elemental distribution can be obtained by appropriately increasing the laser power and reducing the scanning speed.