| Summary: | A mechanically alloyed austenitic stainless steel (MA304LZ) was produced from pre-alloyed SUS304L powder with a small amount of Zr addition. The yield stress of MA304LZ was more than 3 times larger than that of SUS304L or 316L, while total elongation was reduced to about one third of the conventional steels. Microstructure analysis revealed an average grain size of 0.42 µm in MA304LZ and about 34/30 µm in SUS304L/316 L. In MA304LZ, two types of precipitates were observed; inhomogeneously distributed fine precipitates with an average size of 6.0 nm and homogeneously distributed coarse precipitates (d > 20 nm) with an average size of 47 nm. The strengthening mechanism of MA304LZ was discussed on the bases of Hall-Petch and Orowan equations, and the strengthening of MA304LZ was attributed mostly to refined grains. The dislocation barrier strength factor, α, is estimated to be 0.277 for the Zr-rich precipitates in MA304LZ. Keywords: Powder metallurgy, Grain size effect, Precipitation hardening, Zr-oxides
|
|---|
