For the first time ever, the laser powder-bed fusion additive manufacturing equipment installed at Liten two years ago was used to produce parts made from 316LN, a stainless steel alloy used for certain applications that require mechanical properties that go beyond the capacities offered by the traditional 304L and 316L alloys, which contain less nitrogen than the 316LN alloy.
At 99% of the material's theoretical density, the parts produced offer characteristics superior to parts manufactured using the same process, but from other stainless steel alloys such as 316L or 304L. Stress and impact resistance tests on several samples confirmed that the parts' mechanical performance is superior to the minimum requirements in the standards for the forged material. Transmission electron microscope images showed the presence of numerous defects, or dislocations, whose density determines strength.
The process offers an additional benefit that is also significant. It requires just 39% of the minimum amount of energy cited in the literature to produce the parts. "The machine compacts the material, reducing the thermal energy required to melt the bed of powder," said a Liten researcher. This noteworthy advance can be attributed to Liten's expert control of the machine and capacity to adjust the powder's characteristics to the process.
CEA is a French government-funded technological research organisation in four main areas: low-carbon energies, defense and security, information technologies and health technologies. A prominent player in the European Research Area, it is involved in setting up collaborative projects with many partners around the world.