Metallurgical processing technology and cleaning of titanium alloy forging

With the continuous advancement of science and technology, the requirements for material properties are getting higher and higher. Titanium alloys have gradually become a research hotspot due to their superior properties. Titanium alloy forging is an important metal forming process. However, titanium alloy forgings are prone to defects such as inclusions and scale during the production process, which affect the performance of the forgings.

Many materials forging and processing methods are also constantly following up. Products forged from titanium alloys have been widely used in the market. Forging processing technology is becoming more and more mature. Titanium alloy forging metallurgy is relatively common. Let's learn about titanium alloy forging. of metallurgical processing technology and cleaning.

⑴. Direct metal laser sintering rapid prototyping technology

Direct metal laser sintering rapid prototyping technology comprehensively uses advanced laser technology, powder technology and computer control technology to achieve direct processing and forming of nearly dense metal parts. First, a computer-aided design system (CAD) is used to construct a three-dimensional part model of the target product, and then the digital model is decomposed into a series of two-dimensional layer structures. The computer controls the movement of the laser beam, and the powder paving system moves synchronously to lay the alloy powder. , after sintering one layer of fine powder, the system starts to sinter a new layer again, and finally forms a three-dimensional entity of the product after sintering layer by layer.

⑵. Electron beam selective cladding technology

Electron beam selective cladding technology is a manufacturing technology that uses high-energy electron beams to bombard pre-mixed titanium mixed powder and sinter it layer by layer. The titanium metal powder will melt and sinter into a layer under the bombardment of the electron beam and bond with the lower layer that has been cooled and formed. The Swedish Arcam company used this technology to develop the EBM S12 system. The electron beam source part of the equipment heats the upper filament to above 2500°C to release electrons. They are accelerated by the anode and passed through the focusing coil to form a downward bombardment electron beam. The deflection of the electron beam can be controlled by a magnetic field. , the electron beam energy is controlled by current, and the generated power can reach 4kW. During processing, a powder distributor spreads a layer of powder on the working plane in the vacuum chamber, and then the workstation converts the three-dimensional modeling file of the workpiece into components.

Layer profile data and transmitted to the control system. Based on the read profile data, the control system drives the electron beam to perform selective sintering according to a specific scanning path. The titanium metal powder is sintered and accumulated layer by layer under the bombardment of the electron beam until the top layer of the entire part is sintered. The powder form in the unsintered area does not change, and after cleaning, the required three-dimensional titanium alloy parts can be obtained. This system is mainly used in the manufacturing of titanium alloy components in the fields of aviation, aerospace, automobiles, and medical implants. The sintered Ti-6AI-4V titanium alloy has a good metallographic structure and excellent mechanical properties. The reported yield strength is 910~940MPa, the tensile strength is 950~990MPa, the Rockwell hardness is 30~35HRC, and the elastic modulus is 120GPa. However, in practical applications, there are still problems such as the manufacturing size is only limited (the maximum manufacturing size is only 250x250x200mm), and the raw material titanium powder needs to be specially supplied.

⑴ Defect analysis of titanium alloy forgings

During the forging process of titanium alloy forgings, due to the presence of inclusions such as gases and oxides in the metal, it is easy to cause defects such as cracks, pores, and looseness in the forgings, seriously affecting the performance of the forgings. Therefore, cleaning forgings is a key step in improving the quality of forgings.

⑵Classification of Titanium Alloy Forging Cleaning Process

At present, titanium alloy forging cleaning processes mainly include mechanical cleaning, chemical cleaning and electrolytic cleaning. Mechanical cleaning mainly includes shot blasting cleaning, polishing cleaning, etc.; chemical cleaning mainly includes pickling, alkali cleaning, etc.; electrolytic cleaning mainly includes electrochemical scale removal, electrolytic polishing, etc.

⑴The cleaning effect is not ideal

Due to the characteristics of titanium alloy, its surface oxide film is difficult to remove and is prone to hydrogen embrittlement. In addition, part of the cleaning process can easily lead to an increase in surface roughness of titanium alloys, affecting the fatigue performance of forgings.

⑵ The cleaning process causes serious environmental pollution

Some cleaning processes require the use of chemical reagents such as acids and alkalis, which can easily cause environmental pollution during use.

⑶ The process is complex and the cost is high

The titanium alloy forging cleaning process is complex and requires multiple processes, and some processes require the use of special equipment, resulting in higher costs.

Metallurgical processing technology and cleaning of titanium alloy forging are of great significance to improving the performance of forgings. In view of the current problems in the titanium alloy forging cleaning process, future development directions mainly include green and environmentally friendly, high-efficiency and low-cost and high-performance types. Through continuous optimization and improvement of cleaning processes, it will provide strong support for the wide application of titanium alloy forgings in aviation, aerospace, medical and other fields.