Grinding Technology For Titanium Alloy Materials

At this stage, most of the aero-engine parts are made of titanium alloy materials, and according to the assembly requirements, the dimensional accuracy and surface roughness of the finishing surface need to be ground in order to ensure the quality of the surface of the parts. Due to the physical and mechanical properties of the titanium alloy material itself, surface burns and reduced surface integrity are likely to occur during grinding processing, and there is an urgent need to solve the problem of grinding titanium alloy materials, so it is very necessary to choose the right grinding wheel.
1 titanium alloy material properties analysis
The types of titanium alloys are roughly divided into three categories, α titanium alloy, β titanium alloy, α + β titanium alloy. With a small specific gravity, high specific strength, high temperature resistance, corrosion resistance, super memory, non-magnetic, low modulus of elasticity, biocompatibility, this series of excellent make it in a wide range of fields to be applied. Titanium's melting point of 1668 ℃, boiling point of 3400 ℃, higher than nickel-iron, therefore, lightweight heat-resistant become the basis of its excellent, can be in 500 ℃ under long-term work. New titanium alloy long-term working temperature is also high, in 300-350 ℃ its strength is 10 times higher than aluminum alloy. Commonly used α + β titanium alloy strength to 1.2GPa, specific gravity 0.44MPa, specific strength 23-27, are higher than alloy steel. The tensile strength of titanium alloy can be more than 1.5GPa, the processing of which must apply a lot of force, is a typical difficult to process materials.
Titanium's thermal conductivity of 0.036cal, TC11 titanium alloy's thermal conductivity is worse. The modulus of elasticity of titanium is about 1/2 of that of steel, and it is easy to vibrate because of its high resilience during processing.

Titanium alloy contains oxygen, hydrogen, nitrogen, carbon, sometimes including silicon, iron and other impurity elements, these elements carried out a strong reaction to the interstitial type exists in the crystal lattice, can make the titanium alloy strength, plasticity decline, and even make the fracture toughness, low-temperature toughness, fatigue strength, corrosion resistance, cold molding and weldability deterioration. Titanium alloy in high temperature chemistry is extremely high, in a certain grinding temperature, titanium formation of oxidation, nitride protective film, so that the surface layer of hardening brittle, reducing the elasticity, increasing the degree of work-hardening, grinding is easy to attach, clogging the grinding wheel, resulting in grinding overheating, surface integrity is reduced.
2 Titanium alloy grinding wheel selection
2.1 Titanium alloy grinding requires small grinding wheel adhesion, small wear, not easy to block, low grinding temperature
This mainly includes the particle size of the abrasive bond organization shape and size. Ordinary grinding wheel consists of abrasive bond and air holes. The role of the abrasive is to grind the processed material to form a surface that meets the requirements. The role of the binding agent is to bond the abrasive together to form a certain shape and hardness, so that the abrasive grain in the grinding process to maintain a stable trajectory, and can be self-removing. Air holes play a role in the grinding process of chip removal, cooling and lubrication. Common abrasives include corundum series (aluminum oxide), and silicon carbide series. Silicon carbide grinding wheel should be selected for grinding titanium alloy.
2.2 Selection of bonding agent
There are two kinds of bonding agent: resin and ceramic:
(1) ceramic binding agent particles ability, thermal stability and chemical stability, waterproof, heat resistance, corrosion resistance, wear small, long time to maintain the grinding performance, with porous, not easy to clog, high productivity. Brittle, can not withstand large impact load.
(2) resin bond grinding wheel high strength, elasticity, good impact resistance, poor thermal stability, poor corrosion resistance, high temperature will soften and lose strength.
Grinding titanium alloy should choose ceramic bond grinding wheel.
2.3 Selection of grain size
Grinding titanium alloy usually adopts 36#-80# grain size.
2.4 Organizational hardness of grinding wheel
Grinding titanium alloy should usually choose a softer hardness or medium hardness, loose organization of the grinding wheel with large pores.