Get the Facts on… Ti-6242 - a high performance material for mission-critical applications

March 01, 2021
Javier Arreguin AP&C

Titanium alloy powders are known for producing parts with excellent mechanical properties, but different powders are best utilized in specific scenarios. 

We catch up with Javier Arreguin, senior material project manager at AP&C, a GE Additive company, to discuss how and why Ti-6242 (Ti–6Al–2Sn–4Zr–2Mo-0.08Si) is a material best suited to high performance, high temperature applications.
 
What so special about Ti-6242?  Where does it fit into AP&C’s titanium portfolio? 

Ti-6242 is a metal alloy that has both light weight and high temperature resistance properties. It fits in well with AP&C’s portfolio because it is a material that is complicated for other technologies to produce. We specialize in reactive materials - particularly titanium powders - and have industry-leading, in-depth knowledge in both the creation of the powder and how to control the manufacturing process to produce a high-quality part. 

We produce these materials by controlling the oxygen content in the powder, and the result is a high-quality powder, which for additive manufacturing applications, is critical.


Who are the target customers for Ti-6242? What are they looking for and how does this alloy meet their requirements? 

Customers in highly regulated industries where performance is more important than cost, such as the aerospace, military, nuclear industries, but also in motorsports. 

Ti-6242 is one of AP&C’s reactive alloys and the main difference between this and other titanium alloys is the mechanical properties that can be achieved from the material, particularly at elevated temperatures and in terms of creep resistance.

Ti-6242 has a high mechanical strength, weldability, high temperature stability and creep resistance up to temperatures of 500-550°C. Other common titanium alloys, and in particular the industry workhorse Ti-6Al-4V, typically have work temperatures up to 350°C, so you can create a part that functions at much higher temperatures with Ti-62421,2,3

This meets the requirements of certain customers in highly regulated industries such as commercial and military aerospace, and the nuclear energy industry where the parts get very hot, but their function is critical to the overall performance - for example in an engine. Ti-6242 offers a solution when other titanium alloys wouldn’t be suitable.

The fact that Ti-6242 was the first titanium alloy to get an AMS specification specifically for an additive manufacturing application (AMS 7014) is testimony to the interest from the industrial community.

AP&C powders

 
In practice, how do you work with customers to identify the best material solution for their application?

In most cases, our customers already know what type of the material they are looking for. Customers in those industries that are interested in Ti-6242 are driven by the certification of the final product - which requires a high-quality raw material and part. 

However, when a customer is looking to use for guidance, the first two questions we ask tend to ask are, “what is the end application?” and “what are you looking to use the material for?” and we take it from there.

If the customer is looking for a material that is light weight or can withstand high temperatures - and in some cases a combination of both - then we often recommend Ti-6242. 

Ti-6242 is a material that is different to process in additive machines and we also impart our knowledge on how to best process the material into their intended part. 

Ti-6242 has in general, higher resistance to oxidation when you compare it to other titanium alloys for the same particle size distribution (PSD) and is expected to have a higher Maximum Ignition Energy (MIE) for the same PSD. This makes the handling and processing of Ti-6242 easier from an EHS perspective.


Let’s talk about applications. You’ve mentioned one of the key properties is its use at high temperatures. What kind of high-temperature applications is Ti-6242 useful for?

Ti-6242 is used to manufacture lightweight production parts where high temperature stability is critical. For example, it could be well-suited to turbine components, afterburner structures, high pressure compressor blades and airframe hot zones in the aerospace industry. 

Some of the cooler areas would only need lower temperature titanium alloys, but the hot zones benefit from the elevated temperature stability that Ti-6242 provides. 

The main consideration in these applications is that different materials will be needed for different components, so selecting the right material according to the part’s temperature needs is critical.

Ti-6242 is also an exciting material for space applications, where the temperatures can range anywhere from cryogenic up to 500 °C, and in those extremes, you need a material like Ti-6242 that can cope with the different temperature changes.


Now, what about light weighting? What are the considerations for say a motorsport or an aerospace customer? 

The challenge for aerospace is always trying to get the highest mechanical properties, for the lowest weight possible, at the highest temperature. 

In the higher temperature areas, nickel superalloys are often used, but those alloys are twice as dense as Ti-6242. So, switching to Ti-6242 can reduce the weight of engines in the motorsport and aerospace industries, while still meeting the temperature requirements. 

The light weighting offered by Ti-6242 can help to improve both the performance and fuel efficiency of the engines in these industries.


Have any success stories arisen with Ti-6242?

Yes. We have a customer who tried to produce Ti-6242 parts with other methods, with limited success. By switching to our powder, they found a very good improvement in the manufacturing process that led to a higher quality part. 

The part created in this scenario is designed for the medium temperature zone section of an engine – these parts will rotate at high speed, so the fatigue properties of the material are critical.


What role did AP&C play in this success?

The high-quality powder supplied improved the process reliability, reduced the defects in the final part, and they were able to certify the material based on the reliable behaviour of the part – and this was directly linked to powder quality.

The fatigue properties of a material are sensitive to the defects, and one of the best strategies to reduce them in additive manufacturing is to control the raw material. 

Our powders are successful on the market because the quality of the powder is very high, and this helps to improve the control of the process by reducing the final defects in the printed part.

Ti-6242 is challenging to print as it tends to crack from residual stress.  A highly spherical powder, such as our plasma-atomized powder, will improve processability and help to maintain a stable printing process, thus preventing cracking. 


Why should others consider switching to AP&C’s Ti-6242 powder?

Using APC’s Ti-6242 powder, companies in those highly regulated industries I mentioned should have an easier certification process because the optimal processability of our powders will improve the likelihood of successful builds.
 
For every property they produce, they know that if they control the process, they won’t need to worry about the powder. If they control the process, they will always have the properties in the same range for every manufactured part.


Overall Outlook

Ti-6242 is a high-performance material that combines high temperature stability and lightweight properties which are ideal for aerospace, military, and space applications. The potential of this material can only be reached by having a premium raw material - something which AP&C has become known for. 

If you have a high-quality powder and can control the process parameters, then you will always produce a high-quality part. 

If you’d like to find out which AP&C’s high-quality titanium alloy powders are best for your applications, then get in touch with us.

 

1 D. Eylon, S. Fujishiro, F.H. Froes, Titanium alloys for high temperature applications – a review, High temperature materials and processes 6(1–2) (1984) 81–91. 
2 P.A. Blenkinsop, Developments in high temperature alloys, In: Titanium Science and Technology, 1984, pp. 2323–2338. 
3 A.K. Gogia, High–temperature titanium alloys, Defence Science Journal 55(2) (2005) 149–173.

 

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