Metal composite with varying layer hardness is produced with 3D printing

Damascus steel is a type of steel originally used for sword blades. In Germany, a team from Max-Planck-Institut für Eisenforschung (MPIE) and the Fraunhofer Institute for Laser Technology have developed a process that allows this type of steel to be produced layer by layer using a laser 3D printer. Damascus type steel is known for being hard yet tough because it is composed of layers of different iron alloys, and using the 3D printing process, it could be used to make aerospace components and tools for example. Other steels which offer the same properties have not been made for the additive manufacturing process which explains why scientists have not been able to exploit the benefits of this technique yet.

The researchers explain that back when Damascus steel was used for swords, to influence the properties of iron alloys, the only option was to adjust their carbon content. Therefore, they would obtain a type of steel that was either soft yet tough or hard yet brittle. European blacksmiths developed a new technique which consists of folding the alloys into many thin layers to give the steel hard yet tough properties. This is why Damascus steel can usually be recognized by its striped pattern. Following some research, the teams from Germany successfully managed to develop a steel that consists of a single material but is made up of hard and ductile layers to form “Damascus steel”.

Damascus type steel is known for being hard yet tough because it is composed of layers of different iron alloys, it is usually recognized by its pattern.

Creating a metal composite with varying layer hardness

The first step of the process was to develop an alloy that would allow to arrive at the desired properties. Therefore, the researchers developed a material consisting of iron, nickel and titanium. In order to be able to create the desired metal structures, the researchers interrupted the 3D printing process for a certain time after each newly-deposited layer. “We have succeeded in specifically modifying the micro-structure of the individual layers during 3D printing so that the final component has the desired properties – and all this without subsequent heat treatment of the steel,” commented Philipp Kürnsteiner, post-doctoral researcher at MPIE.