Effect of Cr content and its alloying method on microstructure and mechanical properties of high‑manganese steel-bonded carbide

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A high‑manganese steel-bonded carbide with 50 wt% TiC was prepared using powder metallurgy. In particular, two types of binder systems were prepared with Cr: a FeMoCr pre-alloyed powder and a 304stainlesssteel powder combined with FeMo pre-alloyed powder. We investigated the influence of the Cr content and its alloying methods on the microstructure and mechanical properties of steel-bonded carbides. The results revealed that the relative density of the alloys decreased slightly as the Cr content increased, but the transverse rupture strength (TRS) and hardness increased. Additionally, the relative density of alloys prepared with the Fe3.0MoxCr prealloyed powder binder was lower than that of alloys prepared with Fe3.0Mo prealloyed powder combined with 304 stainless steel powder binder; however, the strength and hardness of the former were higher than those of the latter under the same Cr content. In particular, a “black-core gray-rim” structure was formed, and the Mo was primarily distributed in the (Ti, Mo)C rim structure layer. Moreover, the peak value of the impact toughness (IM) was obtained for 1.5% Cr content. The hardness, TRS, and IM of the alloy with 1.5% Cr and Fe3.0Mo3.75Cr prealloyed powder binder were 64.6 HRC, 2278 MPa, and 11.9 J/cm2, respectively. Overall, the IM fracture morphology of the alloys was dominated by the intercrystalline fracture along the hard particle–binder interfaces, supplemented by the plastic tearing of the binder phase. The IM values of these alloys was primarily attributed to the fracture of the binder