Study on process and performance of laser heating assisted micro cutting of alumina ceramics
For the study of alumina ceramic micro turning machining performance, using (IPGPhotonis) fiber laser heating assisted cutting. Due to the high strength and hardness of the alumina ceramics, using cubic boron nitride (CBN) tool for turning experiment. The effects of different processing parameters such as laser power, spindle speed and feed rate on the surface roughness and tool wear were studied. Compared with the experimental results obtained by laser heating and non-laser heating, we found that the surface quality is improved by laser heating, and the service life of the cutter is prolonged.
Tribological Action and Cutting Performance of MQL Media in Machining of Aluminum
The tribological action of MQL media and atmospheric carrier gases was investigated using controlled atmosphere cutting apparatus. The investigation demonstrated their adsorption behavior onto metal surfaces was in close connection with the cutting performance of a lubricant synthetic ester and carrier gases in practical MQL machining. In particular, the presence of oxygen resulted in unfavorable cutting phenomena in MQL machining of aluminum. A unique technique of MQL media treatment was further proposed to prepare oil mist sprays containing microdroplets of water. This advanced technique provided some possibilities of improving the tribological action of MQL media in machining of aluminum.
Evolution of carbide precipitates in Hastelloy N joints during welding and post weld heat treatment
Abstract The effects of welding and post weld heat treatment (PWHT) on the morphology, composition and lattice parameter of the precipitates in the welding joints of Hastelloy N alloy have been investigated. Joint samples were prepared using a gas tungsten arc welding process with ERNiMo-2 fillers, and then solid-solution treated at 1100 °C for 20 min. After welding, eutectic M6C carbides can be observed in the heat affected zones (HAZ) and weld zones (WZ). These eutectic M6C carbides become spheroidized during the following PWHT. The concentration of Si decreases during the transformation from the primary ones to eutectic ones, and then increases during the spheroidizing process. The total concentration of Si + Cr in M6C carbides remains stable during welding and PWHT. At the same time, the heat leads to the outward diffusion of Mo from the M6C carbides, which results in a decrease of the lattice parameter.