A New Nickel-Free High Strength Austenitic Stainless Steel for AM Applications
A new approach was used for the development of high strength austenitic stainless steels, which are particularly suitable for additive manufacturing applications. The new grades employ increased nitrogen and carbon content, which is in contrast with a traditional metallurgical teaching, to provide for an increased strength and an improved corrosion resistance. The desired performance characteristics of the new nickel-free stainless-steel grades are attained by carefully balancing the carbon and nitrogen additions with chromium and manganese to attain the austenitic structure and achieve an improved corrosion resistance, particularly resistance to pitting corrosion. Utilizing this approach, two families of austenitic stainless steels were developed: High Nitrogen Steels (HNS) and High Interstitial Steels (HIS). Both families of steel are suitable for additive manufacturing since rapid cooling following the deposition process prevents formation of detrimental carbides and nitrides, and it helps carbon and nitrogen to remain in solid solution.
This paper will discuss and compare the mechanical properties and performance of the new nickel-free High Strength Austenite (HSA) grade, Printdur HSA, with those of 316L stainless, an establish austenitic steel frequently used in additive manufacturing applications. Test coupons from both materials were produced by laser powder bed fusion process (LPBF). It was demonstrated that the new Printdur HSA grade shows superior characteristics in term of corrosion resistance when evaluated by PREN and MARC numbers, as well as by ASTM G150 corrosion test. The HSA grade also demonstrated good processability and had a higher yield strength, tensile strength, and hardness than those values for 316L