316L stainless steel powder densification during the coupled multi-fields activated micro-forming

Huang, Kunlan and Yang, Yi and Qin, Yi and Yang, Gang (2013) 316L stainless steel powder densification during the coupled multi-fields activated micro-forming. Materials and Manufacturing Processes, 28 (2). pp. 183-188.

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Abstract

In this article, a novel forming and sintering method is introduced for the forming of micro-components in which the loose powders are loaded directly into the die, followed by simultaneous electrical forming and electric-sintering (called coupled multi-fields activation). In the study, Φ1.0 mm × 1.0 mm sized cylinders were formed with 316 L stainless steel powders and the coupled multi-fields activations were enabled with a Gleeble-1500D thermal simulation machine. Sintered sample with relative density of 99.20% has been fabricated at a sintering temperature of 900°C, heating rate of 50°C/s, and pressure of 250 MPa. The study showed that the deformation and breakage of the particles during the combined forming and sintering under the electric field are two critical mechanisms that prescribe the densification process. Due to the deformation and breakage of the particles, an increase and then subsequent disappearance of the interface areas among the particles were observed, which proved to be vital to the densification of the powders and hence, vital to the density that was produced. Based on the experimental observation, a three-stage-sintering model has been established to describe the process of the densification of 316 L stainless steel powders when being formed/sintered under coupled multi-fields activations.