Analysis Of The Core Manufacturing Process And Processing Technology Of Titanium Flange

As the core basic accessory for pipeline connection and sealing and fastening of titanium equipment, titanium flange blocks are widely used in key fields such as chemical anticorrosion, aerospace, nuclear power, and high-end equipment manufacturing due to the excellent characteristics of titanium alloy's lightweight and high strength, high and low temperature resistance, and corrosion resistance. The finished product performance, dimensional accuracy and structural stability of titanium flange blocks directly depend on the selection of manufacturing technology and the control of machining accuracy.

According to the complexity of product structure, operating conditions and performance indicators, the mainstream manufacturing processes in the industry are divided into three core forming processes: precision casting, multi-type forging, and forming and welding. With supporting processes such as mechanical finishing and surface modification treatment, a complete standardized production system of titanium flange blocks is formed. This paper comprehensively analyzes the technical characteristics, applicable scenarios and technical advantages of each core process.

1. Precision Casting Process

Precision casting is the key forming process of special-shaped and high-complexity titanium flange blocks. It is mainly aimed at titanium flange products with special internal structure, many special-shaped curved surfaces, and difficult to form by conventional forging. The process relies on the principle of lost wax precision casting and forming. First, high-precision molds and wax molds are made. After a series of processes such as tree formation, shell making, dewaxing, roasting, vacuum melting, pouring, cooling and shelling, the blank forming of titanium flanges with complex structures is completed at once.

Compared with the traditional molding process, the biggest technical advantage of precision casting is the high degree of freedom of molding. It can form all kinds of titanium flange blocks with unconventional pore sizes, special-shaped end faces, and complex cavity structures in one piece, without the need for a lot of secondary shaping processing. At the same time, the vacuum pouring environment can effectively isolate the air, greatly reduce the oxidation and suction defects of the titanium alloy melt, and ensure that the internal organization of the casting is uniform and the pores are less slag.

This process is mainly suitable for small batches of non-standard titanium flange products with special structures and complex shapes, and can meet the special-shaped assembly needs under special working conditions. It is the core process of customized high-end titanium flange production. However, limited by the characteristics of the casting process, the grain of the casting is relatively thick, and the overall mechanical properties are slightly lower than that of the forging. It is generally suitable for non-high pressure and high load working conditions.

2. Forging And Forming Process

Forging is the mainstream manufacturing process of industrial standard titanium flange blocks, and it is also the preferred forming method for high-performance and high-load titanium flanges. The titanium alloy blank is extruded, forged, and plasticically deformed by external forces, the coarse grains in the cast state are broken, the internal metallographic structure is refined, and the defects such as looseness and pores in the blank are eliminated, and the density, strength, toughness and fatigue resistance of the titanium flange block are greatly improved. According to the different forming molds, processing methods and process parameters, titanium flange forging is mainly divided into three categories: open forging, closed forging, and isothermal forging.

(1) Open Forging

Open forging is a traditional free forging process, relying on the upper and lower flat anvil molds to repeatedly forge, crush and shape the titanium alloy blanks. There is no closed setting mold, relying on manual or equipment to control the deformation shape and size of the blanks.

The process has flexible operation, low mold cost and low production threshold, and is suitable for mass production of ordinary titanium flange blocks with simple structure and conventional specifications. However, the process accuracy is limited, the product dimensional tolerances are large, and the flatness and roundness deviations of the flange end face and aperture are relatively obvious, and a larger machining margin needs to be reserved in the future. The finished product has stable comprehensive mechanical properties and high cost performance. It is widely used in conventional working conditions such as general chemical industry and civil pipelines.

(2) Closed Forging

Closed forging belongs to the precision die forging process. A closed setting mold is used to place the titanium alloy blank inside the mold cavity, and the blank is fully formed by high-pressure extrusion of the equipment. The cavity is formed.

Compared with open forging, the utilization rate of closed forging materials is extremely high, there is no excess flying edge waste, and expensive titanium alloy raw materials are effectively saved. At the same time, the mold is shaped and formed, the product has high dimensional accuracy and regular shape, and the flatness and verticality of the flange end face are consistent, which greatly reduces the margin for subsequent turning and milling. This process has strict requirements for equipment pressure, blank deformation speed, and mold accuracy. It is mainly used for the large-scale production of high-end standardized titanium flanges, and is suitable for medium- and high-pressure and medium-load industrial conditions.

(3) Isothermal Forging

Isothermal forging is the core process of high-end precision forming of titanium alloys. It is specially designed for the customized production of titanium flanges in high-precision fields such as aerospace, nuclear power, and military industry. The core feature of the process is that the blank and the mold maintain the same temperature and constant temperature, and the plastic deformation is completed under a constant high temperature environment.

The constant temperature environment can completely avoid the internal stress caused by the temperature difference in the forging process of titanium alloy blanks, and effectively eliminate product deformation, cracking, rebound and other problems. After forming, the product has extremely high dimensional accuracy and minimal deformation. At the same time, constant temperature and slow deformation can maximize the refinement of the metallographic structure of titanium alloy, so that the product has the comprehensive properties of ultra-high strength, high toughness, high temperature resistance and fatigue resistance. The isothermal forging process has high cost and long production cycle, and is only suitable for high-end titanium flange block products with harsh working conditions and high performance requirements.

3. The Welding And Forming Process

For large-size, ultra-large titanium flanges and split-structure titanium flanges, the industry generally adopts welding and forming technology, which is mainly suitable for supporting flange products for large pressure vessels, large chemical reaction equipment, and large-caliber piping systems. This kind of large-size flange is difficult to forge and cast as a whole, and the cost is extremely high. The welding process can realize split forming and overall splicing, taking into account the production feasibility and structural strength.

Titanium flange welding is mainly based on high-quality welding technology, and the mainstream adopts two processes: tungsten argon arc welding and molten argon arc welding. Inert gas protection is used throughout the welding process to prevent high-temperature oxidation and nitriding of titanium alloys, avoid pores, cracks, inclusions and other defects in the welds, and ensure that the welds are highly consistent with the mechanical properties and corrosion resistance of the base material.

The titanium flange block after precise welding and flaw detection has extremely high structural integrity and sealing performance. The weld strength and sealing properties can meet the special working conditions of high pressure, strong corrosion, and high sealing requirements. It is an indispensable forming process for the production of large-scale special titanium flanges.

4. Supporting Finishing And Surface Treatment Technology

After forming, the titanium flange blank needs to be optimized for dimensional accuracy, appearance quality and service performance through finishing and surface treatment processes. It is the key finishing process for the finished product to leave the factory.

(1) Precision Machining

Whether it is castings, forgings or welding-formed blanks, there are dimensional deviations and surface margins. Precision equipment such as CNC lathes, milling machines, drilling machines, etc. need to be used for turning end faces, fine turning inner and outer diameters, milling sealing surfaces, drilling and tapping, etc. Finishing processing. Through standardized CNC machining, the flatness, verticality, aperture tolerance, and sealing surface roughness of the flange are strictly controlled to ensure that the product exactly matches the assembly standards and guarantees the sealing and assembly accuracy of the pipeline connection.

(2) Surface Modification Treatment

The corrosion resistance, wear resistance, and oxidation resistance of titanium flanges can be further optimized through surface treatment. Common processes in the industry include sandblasting, polishing, and anodizing. Sandblasting treatment can remove oxidized skin, burrs, and impurities on the surface of the blank, and even the surface roughness; mirror polishing can improve the flatness of the flange sealing surface and prevent sealing leakage; anodizing can generate a dense oxide film on the surface of the flange, greatly enhancing the corrosion resistance of the product under extreme working conditions such as strong acid, alkali, and seawater, effectively extending the service life of the product.

5. Conclusion

In summary, the manufacturing process of titanium flange blocks needs to follow the principle of on-demand selection and precise adaptation: open forging is preferred for ordinary conventional working conditions, closed forging is used for standardized middle and high-end products, precision casting is used for special-shaped non-standard products, isothermal forging is used for high-end harsh working conditions, and precision welding is used for large-scale products. At the same time, relying on the supporting technology of finishing and surface treatment, the dimensional accuracy, mechanical properties and corrosion resistance of titanium flange blocks are guaranteed in all directions, and they are fully adapted to the long-term stable operation needs of high-end equipment in various fields.