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Influence of High-Frequency Micro-Forging on Microstructure and Properties of 304 Stainless Steel Fabricated by Laser Rapid Prototyping

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Abstract

We report the fabrication of the 304 stainless steel by the laser rapid prototyping harmonized with high-frequency micro-forging and demonstrate that both microstructure and properties of the prepared samples can be enhanced significantly. Structurally, we find that the large regular dendritic microstructure can be broken into pieces and that the internal defects are to some extent eliminated. Moreover, grains are refined remarkably. As a consequence of such structural modification, mechanical properties are found to be enhanced considerably by demonstrating a much broader fluctuation in tensile strength, a marked increase in tensile and yielding strength, and a drastic enhancement in surface hardness by 76% after the micro-forging. Further calculations reveal that the defect region is shrunken substantially after micro-forging. Detailed analysis of fractures in the tensile samples provides convincing evidence that plastic properties can be improved as well by the micro-forging.

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