高沉积率激光金属沉积Inconel 718的孔隙率控制

Porosity control of Inconel 718 in high deposition-rate laser metal deposition

为降低高沉积率激光金属沉积(Laser Metal Deposition,LMD)工艺中材料的孔隙率,研究了以镍基高温合金Inconel 718(IN718)为粉末沉积材料的高沉积率LMD工艺中主要工艺参数对材料孔隙率的影响,以及通过调整工艺参数降低材料孔隙率的方法。以目标沉积率为2kg/h的LMD工艺为基础,通过参数固化和分离的手段开展了高沉积率LMD的镀层实验,研究了主要工艺参数即激光功率、扫描速度及送粉量对LMD镀层材料孔隙率的影响,分析了不同参数下各镀层的横截面孔隙率及镀层孔隙率。实验显示:当激光功率从1 440 W增加到4 214 W时,镀层材料的孔隙率从约1.5%降低至0.02%左右;当扫描速度为500mm/min至5 000mm/min时,镀层材料孔隙率始终保持为0.07%至0.18%左右;当送粉量从0.64kg/h增加至6.48kg/h时,镀层材料孔隙率从约0.01%增加至0.84%左右。可见在高沉积率LMD工艺中,扫描速度对材料孔隙率无明显影响,而提高激光功率、限制送粉量均可有效降低LMD材料孔隙率,提高横截面孔隙率的一致性。

To reduce the material porosity in Laser Metal Deposition（LMD）processing,the Inconel718（IN718）was used as powder additive in this study,and the influences of main process parameters on the material porosity in a high deposition-rate LMD were investigated.Then,the methods to reduce the material porosity were researched by adjusting these process parameters.Based on the newly developed target with a high deposition rate by 2kg/h in the LMD process,a coating experiment was performed by parameter solidification and parameter separation and the effects of laser power,scanning speed and powder mass flow on the material porosity were designed and carried out.Furthermore,the cross-sectional porosity and track porosity of tracks deposited by different process parameters were analyzed.The results show that as the laser power increases from 1 440 W to4 214 W,the porosity of the longitudinal track decreases from about 1.5% to about 0.02%.When the scanning speed varies in the range of 500mm/min to 5 000mm/min,the range of track porosity is approx.0.07% to 0.18%.Moreover,when the powder mass flow increases from 0.64kg/h to6.48kg/h,the porosity increases from approx.0.01%to 0.84%.It is shown that in high depositionrate LMD,the scanning speed has no obvious influence on the porosity;and increasing laser power and reducing powder mass flow rate significantly reduce material porosity and increase the consistency of cross-sectional porosity.