The Effect of Sub-Zero Treatment on Mechanical Properties of GTAW Welded AA6082

The consequence of sub-zero treatment on the mechanical properties of welded AA6082-T6 by Gas Tungsten Arc Welding (GTAW) which in turn softens the heat concentrated welded region owing to dissolution of the strengthening precipitates. The sub-zero i.e. Shallow Cryogenic Treatment (SCT) is carried out on GTAW welded plate having a thickness of 6 mm at -77°C by varying the electrode travel speed and sub-zero treatment periods. Welded region of AA6082 were tested for hardness and microstructure by adapting three different conditions such as welded, post weld artificial aging with and without sub-zero treatment. Result revealed that the amount of softening in the welded region is indirectly proportional to electrode travel speed during welding process. It is also observed that the post weld SCT with artificial aging has increased the micro hardness values on the welded region as a consequence of the reactivation in the sequence of precipitation.

Sliding Wear Behavior of Cryogenic Treated Copper Beryllium Alloy

In this study, the effect of Shallow Cryogenic Treatment (SCT) on the wear behavior of copper beryllium alloy was investigated. The material is subjected to shallow cryogenic treatment to – 80 °C and wear study was conducted on a pin on disc apparatus. The Shallow Cryogenic treated and untreated copper beryllium alloy pins were used against hardened AISI 4140 steel disc. The micro-structural examination was carried out using optical microscope. The hardness was measured using Rockwell hardness tester. The wear track was studied using optical microscope. Microstructure study indicated that the grains of shallow cryogenic treated samples are finer than that of untreated sample. Hardness of the cryogenic treated sample is higher than that of the untreated sample. The wear resistance of cryogenic treated copper beryllium alloy has improved compared with untreated sample.