Cutting Parameters for Roughing Turning of Alloy 625 Clad Using Ceramic Inserts

Nickel alloy 625 is widely used in submarine equipment for the oil and gas industry, which operate in an extremely adverse environment. In order to reduce the costs of these components, weld overlay cladding is employed. The surface generated by this process presents some irregularities that represent an additional difficulty to the machining process. The present work investigates the use of whiskers-reinforced ceramic tools and SiAlON in turning of alloy 625 clad on AISI 4130 steel by an automatic tungsten inert gas (TIG) cladding system. The results indicate the feasibility of the industrial application of the SiAlON inserts in rough turning of the alloy 625 clad, as well as the impossibility of using whiskers-reinforced ceramic tools (Al2O3 + SiCw) in the same conditions. The highest flank and notch wear of the SiAlON inserts were observed for the lowest cutting speed (140 m/min), which induced the formation of burrs in the workpiece at the depth of cut. Adhesion occurred more intensively at this condition. The least flank and notch wear were achieved by using cutting speed of 160 m/min and feed-rate of 0.25 mm/rev. Prolonged turning with worn tools resulted in microstructural alterations of the workpiece material and surface damages.

625镍基合金（Nickel alloy 625）被广泛应用于油气工业的海底装备中，这类装备的服役工况极为恶劣。为降低此类构件的制造成本，通常采用堆焊熔覆（weld overlay cladding）工艺。该工艺制备的熔覆表面存在诸多不规则缺陷，为后续机械加工带来了额外挑战。
本研究针对自动钨极惰性气体保护（TIG）堆焊系统在AISI 4130钢基材表面制备的625镍基合金熔覆层的车削加工展开，探究了晶须增强陶瓷刀具与赛隆（SiAlON）陶瓷刀具的应用可行性。研究结果表明：赛隆陶瓷刀片可应用于625镍基合金熔覆层的粗加工工业化场景，而在相同切削参数下无法使用晶须增强陶瓷刀具（Al₂O₃ + SiCw）。当切削速度为最低值140 m/min时，赛隆陶瓷刀片的后刀面磨损与缺口磨损均达到峰值，该工况下切削深度处的工件表面会产生毛刺，且刀具与工件间的粘结现象更为严重。当切削速度为160 m/min、进给量为0.25 mm/rev时，赛隆陶瓷刀片的后刀面磨损与缺口磨损均降至最低。采用磨损后的刀具进行长时间车削加工时，会导致工件材料发生微观组织变化，并引发工件表面损伤。