Effects of heat treatment on machinability of aluminum cast alloys

Abstract

Continued from the previous paper, which discussed the effects of various kinds of heat treatments on machinability of cast alloy, AC4B, this paper describes the test results of cutting resistance, tool life, surface roughness, chip form, etc. on aluminum cast alloys; AC2B, AC8A, Al-4Zn-5Mg alloy, and Al-3Zn-3.5Mg alloy: and compares the machinabilities of T6-treated materials of these alloys with those of as cast, F-materials.The results obtained were as follows.The cutting resistance of T6-materials were generally higher than those of the corresponding F-materials. However, the difference between the both was very little in Al-Zn-Mg alloys. Cutting resistances (in particular, traversing forces) of T6-materials of AC2B and AC8A for a cutting tool of high speed steel were increased with the progress of time at a cutting speed higher than a certain value.There appeared an oxidelike-deposit on the tool flank. The aspects of the deposits were different between T6-and F-materials, and the amount of deposit was very small in Al-Zn-Mg alloys.The tool wear was not negligible for AC2B, AC4B, and AC8B; and for T6-materials, it was rapidly increased after a certain degree of time. Whereas, it was very little for Al-Zn-Mg alloys.In general, the surface roughness of F-materials was more excellent with the higher cutting speed. However, the effects of cutting speed was less on T6-materials to obtain considerably smooth surfaces. It was also found that there was very little trouble in chip treatment.