Improved additive manufacturing for superalloys

Materials World magazine
,
1 Jan 2018

Dr Jennifer Unsworth of intellectual property firm Withers & Rogers explains how a new patent makes 3D printing of superalloys easier.

This month’s patent is owned by Materials Solutions Limited and concerns improvements in the fields of 3D printing and additive manufacturing. Specifically, the invention improves a process that can be used to make superalloy components for the aerospace industry.

While designed to withstand high temperatures, superalloys can be prone to cracking and are difficult to weld, which means they can be hard to form using additive manufacturing methods. 

As described in GB2543234, Materials Solutions Limited has overcome these difficulties by developing an enhanced process for the production of superalloy components.

‘One solution to reduce cracking during additive manufacturing is to maintain the bulk part close to its melting temperature during formation,’ it is stated in the official patent documentation. 

‘However, in case of high temperature materials, such as superalloys, the equipment is costly and complex, particularly for laser based systems, and the process is slowed by the need for heat up and cool down times rendering manufacturing costly and difficult to practice.’ 

The process involves building a 3D component layer-by-layer, onto a base plate. Once formed, the component is treated to remove loose powder before a stress treatment is applied to its surface, which causes the component to be compressed. 

It is only after this treatment that the component is removed from the base plate with a low chance of damage. 

While this advantage forms the basis of the granted patent, a number of other process steps are described, which also have associated benefits. For example, the mass of the base plate is reduced. Cutting the base plate into sections and thinning it out, prior to the hot isostatic processing, achieved this. The process also uses a layer of powder not more than 50μm thick, and scan spacing, between the centrelines of adjacent scan lines, of no more than twice this measurement.

After the printed component has been removed from the base plate, a solution heat treatment is applied before it is hardened. 

These additional features have been found to be inventive in their own right and the applicant has secured three patents for its new method. The GB2543234 patent is the last one of this patent family to be granted.

Dividing a single patent application into a number of separate applications, each covering a different feature of a new method or product, can be an effective way of obtaining multi-layered intellectual property protection. This approach gives the patentee a range of options if his invention is subsequently copied, or otherwise challenged.

You can find an exact description of the patent here: bit.ly/2ivEMt