Wide application and future trend of titanium alloy in additive manufacturing

01 Superiority and Challenges of Titanium Alloys

This metal material is titanium alloy, it has high specific strength qualities, and excellent corrosion resistance, and has excellent high temperature mechanical properties, will play a very key role in the field of aerospace, it meets the design of components for high mobility, high reliability and long service life of the stringent requirements of the key indicators to measure the degree of advanced selection of aerospace and spacecraft materials.

At the same time, titanium alloys are biocompatible and have a modulus of elasticity similar to that of human bone, which makes them indispensable in the medical field.

Although titanium alloy has a lot of excellent characteristics, but its processing has always been a difficult problem, the traditional machining means encountered a lot of challenges, such as titanium's low thermal conductivity, work-hardening tendency and low modulus of elasticity, etc., resulting in the manufacture of titanium alloy components are difficult, low material utilisation, manufacturing cycle time is long, high cost, in addition to isostatic pressing, injection moulding and discharge plasma sintering methods are also very difficult to overcome the inherent difficulties of the titanium in the oxygen content and large porosity. In addition, isostatic pressing, injection moulding and discharge plasma sintering are also difficult to overcome the oxygen content in titanium and the porosity and other inherent problems.

The emergence of additive manufacturing technology, to bring revolutionary changes to the manufacture of titanium alloy, it is a near-net forming technology, so that the manufacturing process is greatly simplified, the manufacturing cycle can be shortened, is very suitable for the manufacture of complex structures and customised parts, its high material utilisation characteristics and titanium applications highly compatible with the needs of the field, and more critically, can effectively bypass the traditional processing of titanium problems, since the rise of metal additive manufacturing technology, titanium alloys have rapidly become one of the first Since the rise of metal additive manufacturing technology, titanium alloy has quickly become one of the first materials to be put into use, and has also led to the prosperity of the powder materials market. At present, the global use of titanium powder for additive manufacturing, the annual use of more than 1,000 tonnes, in the additive manufacturing of metal materials in this market, occupies a leading position.

Titanium Alloy Powder Preparation and Market

In the category of metal additive manufacturing, powder materials play an extremely critical role, titanium alloy, as a metal with high performance, its additive manufacturing process for the powder material there are strict requirements, powder particle size distribution, purity, the proportion of hollow powder, flow performance and bulk density and other characteristics will intuitively affect the performance of the formed parts.

Although different additive manufacturing processes have different requirements for powder properties, pure composition, narrow particle size distribution and good flowability have always been the common basic requirements. Spherical powders are widely used in additive manufacturing because of their good flowability and stability. However, the high chemical activity of titanium alloys poses unique challenges, making conventional crucible melting methods unable to meet the purity and low oxygen content requirements.

Therefore, crucible-less melting technologies like Electrode Induction Gas Atomisation (EIGA) and Plasma Rotating Electrode (PREP) have become the main methods to prepare spherical titanium powders. Nowadays, the main additive manufacturing titanium powder suppliers at home and abroad use these advanced preparation technologies. For example, Germany ALD company with its EIGA equipment in the world's leading position, while AP&C company with PA technology as the basis for high-quality spherical titanium powder representatives.

Various preparation methods have their own advantages in terms of powder properties, equipment costs, and production efficiency, however, the high preparation cost of fine particle size powders has been an unavoidable problem. In recent years, the market price of titanium alloy powder for laying powder has been significantly reduced, but, compared with other additive manufacturing powder, its unit price is still relatively high. This is mainly due to the high cost of titanium material itself, as well as its high activity brought about by the processing problems. In addition, the current titanium powder preparation technology, in terms of fine powder yield, in terms of production efficiency, still need to be improved.

Ltd., belonging to the Array Research Technology Group, for the titanium and titanium alloy powder preparation in the melting and atomisation problems, innovative high-frequency induction melting technology and aerosol technology integration, is through the tightly-coupled structure of the atomizer design, the successful preparation of micro-fine spherical titanium and titanium alloy powder, not only to improve the fine powder yield, but also reached a closed condition of continuous production, and thus effectively reduce production costs, this innovative achievement was awarded the China Nonferrous Metals Industry Science and Technology Award. This innovative achievement was awarded the First Prize of Science and Technology of China Nonferrous Metals Industry.

In addition, titanium alloys can be divided into α-titanium alloys, β-titanium alloys and α + β-titanium alloys according to the content of α-phase and β-phase. Among them, α titanium alloy is more outstanding with its high temperature stability and weldability, but its room temperature strength and plasticity are a little lacking; β titanium alloy is outstanding with its excellent deformation ability and room temperature strength.

Application examples and prospects of titanium alloys

In the field of additive manufacturing, α + β titanium alloys have a wide range of applications, in which TC4 alloys are the most prominent, becoming the preferred material in the aerospace and medical fields due to their excellent corrosion resistance and welding ability, as well as their organisation and properties which can be flexibly adjusted according to heat treatment, and which can work stably for long periods of time at temperatures up to 350°C. The material is also used in the aerospace industry. The material can be used in temperatures up to 350°C for long periods of stable operation.

The high temperature strength and stability requirements for materials in the aerospace sector continue to rise in response to continued advances in additive manufacturing technology and the increasing urgency of lightweighting needs. Against this background, α-titanium alloys have gradually gained popularity, especially TA15 alloy, which is capable of working at temperatures up to 500°C for a long time (3,000 hours) and up to 800°C for a short period of time (no more than 5 minutes), and has a life of up to 6,000 hours at 450°C, while maintaining good weldability, making it an ideal choice for partially replacing high-temperature alloys and stainless steels. Selection.

TA15 alloy, is a kind of nearly α-type titanium alloy, has the characteristics of high Al-equivalent, because it has excellent high-temperature strength, has good stability, has excellent heat resistance, there are good corrosion resistance, and there are also good welding performance, so in the field of aircraft manufacturing is widely used, it is often used in the manufacture of fans, but also used in the manufacture of pressurised gas discs, also used in the manufacture of key blades and other structural components. Structural parts.

In recent years, along with the application market continues to expand, titanium alloy powder prices show a rapid decline tendency. At present, whether domestic or imported titanium alloy powder, the price is maintained at 1300 to 1800 yuan per kilogram, and there is still room for further decline. This change prompted the application scope of titanium alloy 3D printing gradually beyond the aerospace field, towards the automotive and large industrial fields continue to extend, the domestic titanium alloy 3D printing powder market has also shown a vigorous development trend.