| Summary: | 碩士 === 大同大學 === 材料工程研究所 === 90 === Abstract
The purpose of this study is to make brazing filler powders with different alloying compositions, via mechanical ball milling to braze 2205 duplex stainless steel by vacuum brazing; and proceed to the corrosion test of the brazed joints, hoping to get the brazed joints that have the similar corrosion properties between matrix and fillers, and further, to improve the corrosion resistance of the 2205 duplex stainless steel brazed joints. The γ phase proportion of 2205 duplex stainless steel is more while the cooling rate is slow. The amount of sigma phase precipitated is increased as the cooling rate was lowered. The starting powder (no milling) exhibits the narrow and sharp main peaks of nickel, boride and silicon elements. After 3 hours milling, most strength peak and exist few little relative weaker peak. From the EPMA analyses, analysis element Fe, Ni, Cr, P and N, of brazing interface. The duplex phase of milting pool were: darker phase is the (Ni,Cr)3P intermetallic compound phase, the white phase was the Ni solid solution with Fe diffusion zone. Adding the Fe element in BNi-7 filler metal, and keeping the Cr amount of filler composition, to approach the chemical composition can decrease the weight loss of brazing joint to 30~40% of brazing joint using as-received BNi-7 filler metal, increasing the corrosion resistance of brazing joint.
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