激光热丝高效沉积Inconel 718熔覆层组织与性能
Microstructure and properties of Inconel 718 cladding layer efficiently fabricated by laser metal deposition with hot wire
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摘要: 对工程构件表面进行强化改性或增材修复能够有效提升零件的服役寿命，减少材料和能源消耗，响应我国绿色和可持续发展战略.本文采用激光热丝沉积工艺在316L不锈钢表面制备了Inconel 718熔覆层，沉积过程中的线能量仅为81.4 kJ/m，焊丝沉积速率高达3.1 kg/h.对Inconel 718熔覆层的微观组织、相组成、显微硬度及耐磨性能进行了研究.结果表明：Inconel 718熔覆层的微观组织由垂直于基材表面和层道界线向熔覆层中心生长的柱状树枝晶构成.γ-Ni相是Inconel 718熔覆层中的基础相，在柱状树枝晶晶间区域检测到了呈“链状”和“岛状”分布的Laves相.Inconel 718熔覆层的平均显微硬度为268.89 HV1，比316L不锈钢基材的显微硬度高37%.Inconel 718熔覆层的平均摩擦系数为0.53，摩擦质量损失为316L不锈钢基材的23.9%，磨损表面由细微的划痕和少量的剥落构成，磨损机制为粘着磨损.Abstract: Enhancing the performance of engineering components through surface modification or additive repair can effectively increase the service life of parts, in support of green and sustainable development strategy. In this study, Inconel 718 cladding layers were prepared on the surface of 316L stainless steel using the hot-wire laser metal deposition technology, with a line energy of 81.4 kJ/m and a wire deposition rate up to 3.1 kg/h. The microstructure, phase composition, microhardness, and wear resistance of the Inconel 718 cladding layer were investigated in detail. The results revealed that the microstructure of the Inconel 718 coatings was predominantly comprised of numerous columnar dendrites. The columnar dendrites grew vertically from the substrate surface or the boundaries between adjacent deposited tracks towards to the center of the coating. The γ-Ni phase was identified as the primary phase in the Inconel 718 cladding layer, with a "chain-like" and "island-like" distribution of Laves phase detected in the inter-dendritic regions. The average microhardness of the Inconel 718 coating was measured at 268.89 HV1, which was 37% higher than that of the 316L substrate. Moreover, the average friction coefficient of the Inconel 718 cladding layer was determined as 0.53, with a friction mass loss of 23.9% compared to the substrate of 316L stainless steel. The worn surface of the Inconel 718 coating was characterized by fine scratches and minor peeling, indicating an adhesive wear mechanism.
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