Titanium and titanium alloys have many characteristics such as light weight, high strength and corrosion resistance. Titanium and its alloys not only have very important applications in the aviation and aerospace industries, but also have begun to be used in chemical, petroleum, light industry, power generation, metallurgy, etc. Widely used in many civil industrial sectors. However, titanium and titanium alloys are still smaller than steel in terms of absolute hardness and strength. The disadvantages of titanium alloy wire made of titanium in terms of hardness limit its application breadth and depth. It is committed to increasing the hardness of titanium alloys on the premise of ensuring the corrosion resistance of titanium and titanium alloys, and surface carburizing treatment is one of the typical treatment techniques. Similar to the surface carburizing treatment of steel, the surface carburizing treatment of titanium alloys also makes the carbon atoms with high activity diffuse into the interior of the titanium alloy to form a carburized layer with a high carbon content of a certain thickness, which is then quenched/tempered , so that the surface layer of the workpiece obtains titanium alloy wire with high carbon content, and the core part obtains titanium alloy with low carbon content because the carbon content maintains the original concentration. The hardness of titanium alloy is mainly related to its carbon content, so after carburizing treatment and subsequent Heat treatment can make the workpiece obtain the properties of outer hard and inner toughness.
The solubility of carbon in titanium is small, totaling 0.3% at 850X, and about 0.1% at 600C. Due to the low solubility of carbon in titanium, it basically only passes through the titanium carbide layer and its lower fork domain. Deposition layer to achieve the purpose of surface hardening. Carburizing must be carried out under the condition of deoxygenation, because the hardness of the surface layer formed by the powder suitable for steel carburizing against the surface of carbon monoxide or oxygen-containing carbon monoxide reaches 2700MPa and 8500MPa, and it is easy to peel off.
In contrast, carburizing in charcoal may form a thin layer of titanium carbide under deoxidizing or decarburizing conditions. The hardness of this layer is 32OUOMPa, which is in line with the hardness of titanium carbide. The depth of the carburized layer is substantially greater than the depth of the nitrided layer when nitriding with nitrogen under the same conditions. In oxygen-enriched conditions, it must be taken into account that the absorption of oxygen affects the depth of hardening. Only in very thin layer thickness conditions, it is possible to infiltrate carbon powder in a vacuum or an argon-methane atmosphere to form sufficient adhesion strength. Compared with this, the use of gas carburizing agents may form particularly hard and good adhesion. hardened layer of titanium carbide. At the same time, the hardening developed under the condition of temperature between 950T: and 10201: is between 50fim and . As the layer thickness increases, the titanium carbide layer becomes more brittle and tends to peel off. In order to avoid the intrusion of carbon inclusions into the titanium carbide layer due to the decomposition of ruthene, a regulation of approximately 2% by volume of ruthene should be used. Dosage Additives Gas carburizing in inert gas. Lower surface hardness results when carburizing with methane using propane additives. When the bonding strength reaches 9000kPa, when gas carburized propane is used, although the measured thickness of the hardened layer is very thin, it has the best wear resistance. Hydrogen is absorbed under the condition of gas-type carburizing agent, but it has to be removed again during vacuum annealing.
