扫描速度对激光沉积ER630丝材修复层力学性能与显微组织的影响

Effect of scanning speed on mechanical properties and microstructure of ER630 wire repair layer by direct laser deposition

采用直接激光沉积法(DLD)在45钢基材上激光沉积ER630丝材,研究了扫描速度对ER630丝材修复层力学性能和组织的影响。结果表明,随着扫描速度的不断提高,ER630修复层中夹渣逐渐增多,且尺寸逐渐增大;扫描速度对ER630丝材修复层密度的影响可忽略不计。在30 mm/s扫描速度下,组织主要为板条柱状马氏体和少量圆胞状奥氏体,随着扫描速度的提高,板条柱状马氏体减少,圆胞状奥氏体逐渐增多。在30 mm/s扫描速度下,激光沉积丝材试样的力学性能与550℃时效处理的630不锈钢相当。随着扫描速度的提升,屈服强度与硬度均呈下降趋势,30 mm/s时屈服强度最大,为961.07 MPa, 40 mm/s时硬度最大,为428.88 HV。拉伸断口形貌为韧窝断裂或准解理断裂,可见DLD工艺可实现优异的冶金结合;比较30 mm/s扫描速度下的强度,当沉积效率提高至2倍时,仍能得到较好的修复强度。

Effect of scanning speed on mechanical properties and microstructure of ER630 repair layer was studied by direct laser deposition(DLD) on 45 steel substrate. The results show that with the increase of scanning speed, the slag inclusion in the ER630 repair layer gradually increases and the size gradually increases. The effect of scanning speed on the density of ER630 repair layer is negligible. At the scanning speed of 30 mm/s, the microstructure is mainly lath columnar martensite and a small amount of cellular austenite. With the increase of scanning speed, the lath columnar martensite decreases and the cellular austenite gradually increases. The mechanical properties of the laser deposition wire specimen at the scanning speed of 30 mm/s are equivalent to those of the 630 stainless steel aged at 550 ℃. With the increase of scanning speed, the yield strength and hardness show a downward trend. The maximum yield strength is 961.07 MPa at 30 mm/s, and the maximum hardness is 428.88 HV at 40 mm/s. The tensile fracture morphology is dimple fracture or quasi-cleavage fracture, indicating that the DLD process can achieve excellent metallurgical bonding. Compared with the strength change at scanning speed of 30 mm/s, when the deposition efficiency is increased to 2 times, good repair strength can still be obtained.