Preparation and mechanical properties characterisation for high-nitrogen steel

Abstract

SS304 and SS316 are widely used austenitic steels in various industries. Both alloys contain high amounts of nickel (Ni). With the recent trend of Ni prices increasing, alternative austenitic steels where Ni is reduced or absent are being researched to reduce the cost of austenitic steels. A potential alternative class of austenitic steels can be used to substitute SS304 and SS316 is HNS. HNS austenitic steels are not as widely used due to the challenges faced in producing it commercially. As such using AM like Selective Laser Melting (SLM) to produce HNS is seen as the next step in producing this material. A*STAR Institute of Materials Research and Engineering has developed a type of HNS produced via AM, and this study seeks to prepare and characterise the mechanical properties of this HNS. Microhardness, observation of microstructure and porosity, and tensile test was conducted on samples of this HNS. The results obtained from the various tests indicate that most of the mechanical properties are equal to or better than SS304 and SS316. As the material is still in an experimental stage, further optimisation of manufacturing processes and material composition may lead to further improvements of such mechanical properties. As such it indicates that HNS produced via AM may be able to replace SS304 and SS316.