预应力切削镍基高温合金的试验研究

Experimental Study on Prestressed Cutting of Nickel-based Superalloys

针对镍基高温合金在切削后加工表面分布严重的残余拉应力等问题,提出采用预应力切削方法,以实现在加工过程中主动控制加工表面残余应力分布状态;通过研制轴类零件的车床专用预拉伸装置,在0 MPa、150 MPa和300 MPa三种预应力条件下对高温合金轴件进行预拉伸处理;通过硬质合金刀具预应力切削镍基高温合金的对比试验,对三种预应力条件下的切削力、切屑形态以及表面完整性包括已加工表面残余应力、加工表面粗糙度、表面形貌和显微硬度等指标进行对比。结果表明:在一定范围内,采用预应力切削方法可省去加工后续的残余应力调整工序,并能在加工表面获得合适的残余压应力;残余压应力的值可通过调整施加的预应力大小来进行主动控制;与普通切削相比,预应力切削可得到均匀的锯齿形切屑,切削力没有显著增加;预应力切削可获得良好的表面完整性,且不会引来额外的加工硬化。

In view of the serious residual tensile stress distribution on the machined surface in cutting nickel-based super-alloy,the utilization of prestressed cutting method is proposed to actively control the residual stress distribution status on the machined surface in machining process.Nickel-based super alloy shafts are pre-stretched at the condition of 0 MPa,150 MPa and 300 MPa by a lathe-specific pretension device respectively.A comparison experiment with cemented carbide cutter cutting nickel-based super-alloy in three conditions of prestressed turning is carried out.The cutting force,chip formation and surface integrity indexes including residual stress on machined surface,surface roughness,surface topography and micro-hardness are compared and studied.The results show that in certain extent suitable compressive residual stress on machined surface are achieved by utilizing the prestressed cutting method;meanwhile procedures of residual stress adjustment after machining can be omitted.Furthermore,the magnitude of compressive residual stress can be actively controlled by adjusting the magnitude of prestressed force.To compare with normal cutting process,uniform saw-tooth chip are generated in pre-stressed cutting,meanwhile there＇s no significant increment of cutting force.Prestressed cutting method can generate good surface integrity without any additional hardening.