粉末低合金鋼之強化製程與顯微破壞機制
Date Issued
2004
Date
2004
Author(s)
吳明偉
DOI
zh-TW
Abstract
傳統粉末冶金製程可大量生產淨形(net-shape)之機械或構造用零件，由於現今對機械零件之機械性質要求相當精密且嚴苛，故為了提升粉末冶金零件之競爭力，本研究分別探討氣氛、燒結溫度、合金元素、生胚碳含量及不同回火溫度對擴散型合金粉的影響，以期找出最佳的製程參數。
結果顯示，使用氮氫混合氣氛91％N2+9％H2、燒結溫度由1200℃提升到1250℃時並添加316L不
Traditional powder metallurgy (P/M) process can produce economically net-shape mechanical or structural parts in quantity. To improve the competitiveness of P/M parts, this study investigates the influence of atmosphere, sintering temperature, alloying element, carbon content , and tempering temperature on the mechanical properties of diffusion-bonded steel powders.
The results show that 91%N2+9%H2 atmosphere, 1250℃ sintering temperature, and adding 316L stainless steel powder will improve the mechanical properties of sintered parts. Increasing the carbon content from 0.6wt% to 0.8wt% is not helpful. Adding 316L stainless steel powder decrease slightly the carbon content of sintered parts and the heat-treated mechanical properties. Increasing tempering temperature from 180℃ to 230℃ can effectively increase the heat-treated mechanical properties.
This study also investigates the microfracture behavior of sintered parts using an in-situ tensile test. It was found that the microcrack initiates at the Ni-rich ferrite grain boundary near the neck region and propagate easily along the boundary. The microstructure around pores and the heterogeneous structure can effectively delay crack nucleation and propagation and thus improve the mechanical properties of sintered parts.
Subjects
傳統粉末冶金
動態拉伸試驗
異質結構
擴散型合金粉
in-situ tensile test
Powder metallurgy
diffusion-bonded powder
heterogeneous structure
Type
thesis
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