Understanding the deformation behavior of 17-4 precipitate hardenable stainless steel produced by direct metal laser sintering using micropillar compression and TEM

Micropillar compression testing and transmission electron microscopy were used to investigate the deformation mechanisms under compression in 17-4 precipitation-hardening stainless steel, fabricated by direct metal laser sintering. The as-built specimen as well as that aged for 4 h at 866 K contained fractions of retained austenite, while that aged for 60 min at 755 K was fully martensitic. It was observed that the columnar elongated grains underwent martensite/austenite phase changes with changes in the aging temperature. The precipitate phase that developed with aging enhanced the material hardness and yield strength, with values being higher in the case of the specimen aged at a lower temperature for a shorter time. The results showed that the microstructures and properties of 17-4 stainless steel specimens fabricated by DMLS vary significantly from those of specimens produced using conventional methods.