Gr12 Titanium Material Plasticity Processing

The process of processing Gr12 titanium material ingots into semi-finished products by plastic deformation method is one of the titanium material preparation processes. Industry commonly used processes such as forging, rolling, extrusion, stretching, etc. has been able to produce a variety of specifications of the plate, bar, wire, pipe and forgings. Its process flow is shown in Figure. Titanium material plastic processing characteristics are: deformation resistance, low plasticity at room temperature, yield limit and strength limit of the ratio of high, deformation rebound, deformation process is easy to bond with the mold and so on.
Heating The deformation resistance of titanium materials decreases with increasing temperature, and the plasticity increases with increasing temperature. Especially for highly alloyed iron alloy, heating deformation is the main deformation mode. In the ingot open billet forging, heating is a necessary process. Titanium's thermal conductivity is poor, in the heating process, must control the rate of temperature rise, in order to prevent the formation of large thermal stress in the ingot. For some highly alloyed ingots, this thermal stress may cause cracking. In the resistance furnace or flame furnace heating time, generally calculated according to the cross-section size 1min / mm. For highly alloyed ingots to be slower. For this reason, segmented heating is often used. If induction heating is used, the time required is significantly reduced. Titanium materials are chemically active and easily absorb oxygen, nitrogen and hydrogen when heated. When heated in the air, the surface of the billet will form an oxide skin and an air-absorbing layer. Too thick air-absorbing layer will cause cracking when deformed and deteriorate product quality. If the hydrogen absorption of titanium material exceeds the standard value, hydrogen embrittlement may occur in future use. In order to reduce oxidization during heating, protective coating is an effective method. In order to prevent hydrogen absorption, it is best to use a neutral atmosphere furnace when heating, such as electric furnace. When heating with a flame furnace, control the furnace for a slightly oxidizing atmosphere. When titanium material is heated, if it is in contact and friction with iron oxide and steel frame, it may cause local melting or even burning.

Titanium material plasticity processing
Forging is the titanium ingot processing into an intermediate billet must be processed, generally known as open billet forging. At the same time, forging is also used as an independent process for the production of bars, forgings and drop-forged parts and other products. Forging equipment is generally used for forging hammers or hydraulic presses, can also be used fast forging machine and precision forging machine. The temperature of the open billet forging is generally selected in the β-phase area, and the subsequent forging should be selected in the upper part of the a-β-phase area. A fire deformation is about 30% to 70%. In view of the sensitivity of titanium alloy properties to the organization, the development of the forging process should be able to meet the creation of optimal recrystallization conditions to obtain the best overall performance of the organization. Titanium material in the heating and deformation, deformation heat has a great influence. Local intense deformation zone generated by the heat r under the influence of its own low thermal conductivity, will produce local overheating, so that the organization deterioration. However, if the deformation rate can be controlled and make the deformation uniform, the deformation heat is again favorable to processing. The deformation resistance in forging increases rapidly with the deformation rate. Forging at the same temperature, the energy required to use a forging hammer is higher than that of a hydraulic press. The deformation rate also has an effect on the plasticity of the material. In recent years, in addition to the use of conventional forging, B forging and near-net forming technology has been developed.
Extrusion The extrusion method produces tubes, bars and profiles. Titanium material is easy to stick to the mold when extruding. If the lubrication is poor, not only to damage the mold, and will make the extruded surface to form longitudinal "groove" defects. Commonly used lubrication methods are coated with glass lubricant or metal sleeve, or coated with graphite-based lubricants.
Plate, strip, foil rolling There are three methods of hot rolling, warm rolling and cold rolling. In addition to p-type titanium alloy, hot rolling should generally be in n or a-B phase g-i left line. Hot rolling temperature is 50-100 ℃ lower than the forging temperature. Thick 2 to 5ram plate can be used for warm rolling process, thinner size of the plate can be cold rolled. Cold rolling between the two annealing deformation of 15% to 60%. In order to ensure the quality of the plate and rolling process smoothly, should be used in the middle of the annealing and surface treatment and other process measures. The use of strip rolling, continuous pickling and continuous annealing and other units, can produce several tons of titanium strip coil weight per roll.
Tube rolling Thick-walled tubes can be produced by extrusion or slant rolling method, small diameter thin-walled seamless tubes need to be cold rolled or stretched. Titanium alloy plasticity in the cold state is limited, sensitive to notch, easy to work hardening, easy to stick mold. In order to improve the rolling of titanium alloy tubing, warm rolling process can be used. Rolled tube quality depends largely on the ratio of wall thickness reduction rate and diameter reduction rate, when the former is greater than the latter, you can get good quality tubes. In addition, the rolled thin strip coil as a billet, in the welded pipe machine series by cutting, coiling, welding into thin-walled welded pipe, has also been widely used in electric power, chemical industry.