钛铝金属间化合物电解线切割精整加工试验研究

Experimental Study of WECM Trimming for Titanium-Aluminum Intermetallic Compounds

提出了电火花线切割与电解线切割组合加工钛铝金属间化合物TiAl 45XD材料的方法,其中电解线切割精整加工一次“走刀”去除重铸层,二次“走刀”消除可能出现的晶间腐蚀。分别研究了铸造TiAl 45XD机械抛光表面和电火花线切割表面的电化学特性,发现两种表面在水基溶液中均有钝化现象,在乙二醇基溶液中几乎无明显的钝化现象,与在水基溶液中相比,两种表面在乙二醇基溶液中均更易被腐蚀,且电火花线切割表面较机械抛光表面的腐蚀程度更高。分析了进给速度和切深对表面完整性的影响,试验结果表明:一次“走刀”进给速度为25μm/s、切深为20μm,二次“走刀”进给速度为60μm/s、切深为0时,重铸层被去除,无晶间腐蚀,表面粗糙度值减小至1.6μm,平均进给速度为17.65μm/s。该试验结果验证了使用电火花线切割粗成形、乙二醇基溶液电解线切割精整加工钛铝金属间化合物是可行的高表面完整性直纹构件加工方法。

A method of machining titanium-aluminum intermetallic compounds TiAl 45XD was proposed by combining WEDM and WECM.During the WECM,the recast layers were removed by first“pass”,and the possible intergranular corrosions were eliminated by second“pass”.The electrochemical characteristics of the cast TiAl 45XD mechanical polished surfaces and the WEDM surfaces were studied respectively.It is found that both of the surfaces have passivation in water-based solutions(WBS),and there are almost no obvious passivation in glycol-based solutions(GBS).Compared with the WBS,both of the surfaces are more susceptible to corrosion in the GBS,and the WEDM surfaces are more corroded than that of the polished surfaces.Then the effects of feed speed and cutting depth on surface integrity were analyzed,the testing results show that when the feed speed of first“pass”is as 25μm/s and the cutting depth is as 20μm,the feed speed of second“pass”is as 60μm/s and the cutting depth is as 0,the recast layers are removed,the intergranular corrosions are eliminated,the surface roughness value is reduced to 1.6μm,and the average feed speed is as 17.65μm/s,which proves that the use of WEDM for rough forming,WECM with GBS for trimming is a feasible method for machining straight-grained titanium-aluminum intermetallic compound components with high surface integrity.