Forging method, performance analysis and application fields of titanium forgings
The main methods used in AMS 6931 Titanium Forging are free forging, open die forging (with burr forging), closed die forging (without burr forging), extrusion die forging, multi-directional die forging, sub-die forging Forging, isothermal die forging, its characteristics are as follows:
(1) Free forging. Free forging is generally carried out between two flat dies or dies without a cavity. The tools used in free forging are simple in shape, flexible, short in manufacturing cycle and low in cost. However, the labor intensity is high, the operation is difficult, the productivity is low, the quality of the forging is not high, and the machining allowance is large. Therefore, it is only suitable for use when there is no special requirement for the performance of the parts and the number of pieces is small. For large forgings, free forging is mainly used as a billet making process. The free forging billet process can forge the billet into a stepped bar, or use upsetting or flattening to make the billet into simple shapes such as round cakes and rectangles.
(2) Open die forging (die forging with burrs). The blank is deformed between two modules engraved with a cavity, the general part is confined inside the cavity, and excess metal flows out from the narrow junction between the two dies, forming burrs around the forging. The metal is forced into the shape of the cavity by the resistance of the mold and surrounding burrs
(3) Closed die forging (die forging without burrs). During closed die forging, no transverse burrs are formed perpendicular to the direction of die movement. The cavity of a closed forging die has two functions; one part of it is used to shape the blank, and the other part is used to guide it.
(4) Extrusion die forging. There are two kinds of extrusion die forging, forward extrusion die forging and reverse extrusion die forging. Extrusion die forging can produce various titanium rings. Forgings with high geometrical precision and denser internal structure can be obtained.
(5) Piercing punches make the metal flow outward from the center of the cavity to fill the cavity. There is no burr of ordinary forgings on the parting line of cylindrical parts.
(6) Partial die forging. In order to forge large integral die forgings on the existing hydraulic press, segmental die forging, backing plate die forging and other partial die forging methods can be used. The characteristic of the sub-die forging method is to process the titanium cake segment by segment, one part at a time, so the required equipment tonnage can be very small. Generally speaking, this method can be used to process large forgings on medium-sized hydraulic presses.
(7) Isothermal die forging. Before forging, the mold is heated to the forging temperature of the blank, and the temperature of the mold and the blank is kept consistent during the whole die forging process, so that a large amount of deformation can be obtained under the action of a small deformation force. Isothermal die forging is very similar to isothermal superplastic die forging, the difference is that before die forging, the blank must undergo superplastic treatment to make it have fine equiaxed grains.
Metal can improve its structure and mechanical properties after forging. Due to the deformation and recrystallization of the metal after the casting structure is thermally processed and deformed by forging, the original coarse dendrites and columnar grains become an equiaxed recrystallization structure with finer grains and uniform size, so that the original segregation, The compaction and welding of porosity, pores, slag inclusions, etc. will make the structure more compact and improve the plasticity and mechanical properties of the metal.
Generally speaking, the mechanical properties of castings are lower than those of forgings of the same material. In addition, the forging process can ensure the continuity of the metal fiber structure, so that the fiber structure of Grade 5 Titanium Forging is consistent with the shape of the forging, and the metal streamline is complete, which can ensure that the parts have good mechanical properties and long service life. Precision die forging, Forgings produced by cold extrusion, warm extrusion and other processes are incomparable to castings.
1. Aircraft forgings
Calculated by weight, about 85% of the components on the aircraft are forgings. Turbine discs, rear journals (hollow shafts), blades, wing spars, fuselage ribs, wheel brackets, and inner and outer cylinders of landing gear are all important forgings related to aircraft safety. Aircraft forgings are mostly made of high-strength wear-resistant and corrosion-resistant aluminum alloys, titanium alloys, nickel-based alloys and other precious materials. In order to save materials and energy, most aircraft forgings are produced by die forging or multi-directional die forging presses. Automobile forging is calculated by weight, and there are 1719% forgings on automobiles. A general car is composed of 15 parts such as body, trunk, engine, front axle, rear axle, frame, gearbox, drive shaft, steering system, etc. The characteristics of automobile forgings are complex shape, light weight, poor working conditions, and high safety. High standard. For example, crankshafts, connecting rods, camshafts used in automobile engines, front beams required for front axles, steering knuckles, half shafts used for rear axles, half shaft bushings, transmission gears in axle boxes, etc., are all related Security key forgings for safe operation of automobiles.
2. Diesel engine forgings
Diesel engine is a kind of power machinery, and it is often used as an engine. Taking a large diesel engine as an example, the forgings used include cylinder head, main journal, crankshaft end flange output end shaft, connecting rod, piston rod, piston head, crosshead pin, crankshaft transmission gear, ring gear, intermediate gear and oil pump There are more than ten kinds of body and so on.
3. Marine forgings
Marine forgings are divided into three categories, main engine forgings, shafting forgings and rudder forgings. Main engine forgings are the same as diesel engine forgings. Shafting forgings include thrust shaft, intermediate shaft and stern shaft, etc. Rudder system forgings include rudder stock, rudder post, rudder pin, etc.
4. Weapon forgings
Forgings occupy an extremely important position in the weapon industry. By weight, 60% of the tanks are forgings. Gun barrels, muzzle brakes and gun tails in artillery, rifled barrels and triangular bayonets in infantry weapons, rocket and submarine depth charge launchers and fixing seats, stainless steel valve bodies for nuclear submarine high-pressure coolers, shells, Bullets, etc., are all forged products. In addition to steel forgings, other materials are used to make weapons.
5. Petrochemical forgings
Forgings are widely used in petrochemical equipment. Such as manholes and flanges of spherical storage tanks, various tube sheets required for heat exchangers, welded flanges, whole forging cylinders (pressure vessels) of catalytic cracking reactors, cylinder joints used in hydrogenation reactors, chemical fertilizers The top cover, bottom cover and head required by the equipment are all forgings.
