Experimental Research On The Grinding Performance Of Microcrystalline Alumina Grinding Wheels On Titanium Alloy

Owing to its excellent physical and mechanical properties, titanium alloy has been widely used in many fields and become a significant structural material in astronautics and aerospace industries. As a typical difficult-to-cut material, the grinding of titanium alloy is characterized by severe workpiece adhesion and grinding wheel blockage, large grinding force, high grinding temperature and low grinding ratio. These grinding characteristics have high requirements for grinding wheels. Microcrystalline alumina abrasive is a new corundum type abrasive made by sol-gel preparation technology with special structure of grains. It has the advantages of good self-sharpening ability and long lifespan of wheel. However there were not many studies focused on its grinding performance of titanium alloy.Grinding experiments of titanium alloy TC17 were conducted with microcrystalline alumina (SG) and white fused alumina (WA) grinding wheels to study their grinding performance differences. The results were evaluated by surface integrity, grinding force and wheel blockage. The microstructure and wear mechanism of white fused alumina and microcrystalline alumina grains were also studied. The main work includes:(1) The surface integrity of workpieces ground by WA and SG wheels were studied. The surface observation of workpiece ground by SG wheel shows uniform and clear grinding marks without any grinding surface damage such as grinding cracks or grinding burns. SG wheel made better surface quality, the surface roughness is improved by 0.1 ?m and the surface residual stress, the thickness of white layer and thermal affected (soften) layer all have a 40% reduction. Compared to WA grinding wheel, the surface integrity of ground workpiece was obviously improved by SG grinding wheel.(2) Grinding force experiments of titanium alloy TC17 were conducted with SG and WA grinding wheels under the same grinding condition. The results showed that the tangential grinding force of SG wheel was 8% lower than WA wheel and the normal grinding force of SG wheel was 9% lower than WA wheel. The grinding force could be reduced about 10% by microcrystalline alumina abrasive. Single factor tests were conducted to study the influence of grinding parameters on grinding force with SG wheel. The results showed that optimal grinding parameters for TC17 with SG wheel are:linear speed of grinding wheel vs=27m/s, grinding depth ?p=0.01mm, workpiece feed rate vw=12m/min.(3) The topography of WA and SG grinding wheels before and after grinding were observed and compared. The phenomena of workpiece adhesion and wheel blockage are alleviated by SG wheel. The microstructure and wear mechanism of WA and SG grains were observed and studied. The results showed that SG grains are characterized by microcrystalline structure and the wear mechanisms of two grains are different. The micro-chipping wear mechanism of SG grains loses fewer grains and reveals more sharp edges located under the grain surface. In this way, the grinding force and temperature are reduced and the surface integrity is improved by SG wheel. The unique wear mechanism is the primary cause for the grinding performance advantage of SG wheel.