DEVELOPMENT OF FERRITE-CONTENT CONTROL PROCESS FOR 316LN AUSTENITIC STAINLESS STEEL FOR LIQUID-HYDROGEN STORAGE BASED ON HIGH-FLUX PREPARATION

Designing multiple alloy compositions to achieve target performance is the first step in modern new-material development, but traditional trial-and-error experiments severely hinder progress due to their low efficiency. This article proposes the use of a multi-crucible synchronous metallurgy method in high-throughput experiments to accelerate the composition design of 316LN austenitic stainless steel for liquid hydrogen storage. Twenty as-cast samples of austenitic stainless steel with different compositions were prepared using a high-throughput material preparation system through two rounds of experiments. Then, through microscopic observation and mechanical property testing, the chemical composition that best matched the target performance was ultimately selected. The research results indicate that high-throughput experiments can greatly improve the efficiency of optimizing the composition design of new stainless steel products. Meanwhile, this investigation also analyzed the precipitation of -ferrite in austenitic stainless steel and proposed effective methods for controlling the content of -ferrite. The high-temperature -ferrite in 316H stainless steel originates from the solidification process. Due to the redistribution of elements during solidification, Cr and Mo tend to segregate at dendrites or grain boundaries, forming regions enriched in these elements, resulting in the nucleation and growth of ferrite. This investigation uses a metallographic microscope, electron probe, EBSD and other methods to study the distribution of Cr, Mo and other elements in the microstructure of 316LN stainless steel, observe the evolution morphology of different microstructures, as well as explore how ferrite content changes with chemical composition and production process. It was ultimately determined that high-temperature and long-term sensitization treatment is an effective method to control the content of -ferrite. Tof δ-fer