304不□鋼纖維機械性質與應力腐蝕之研究

Abstract

本實驗係研究304不□鋼纖維之機械性質、顯微結構與其應力腐蝕性質，而不□鋼纖維的線徑分別為40、50、70μm。 由顯微結構可以知道纖維的晶粒大小約為1~5μm，而其抗拉強度隨著拉伸速率越快，抗拉強度越高，抗拉強度可到達900MPa以上。在應力腐蝕性質方面，採用的溶液為稀鹽酸，濃度分別為0.6M、0.8M、1.6M，應力大小不同，不□鋼纖維的破斷時間也不同。由實驗結果可以知道在0.6M與1.6M濃度下，其應力與破斷時間的圖呈現線性的關係，而在0.8M時卻呈現兩段斜率的現象。而在溫度較高的情況(40℃、50℃)，破斷時間由於溫度的活化也加快了反應速度，使得破斷時間減短了許多。對於拉伸及應力腐蝕的破斷面做SEM顯微結構分析。

In this study, the major experimental materials were 304 stainless steel fibers whose diameters were 40、50 and 70μm, respectively. Microstructure, mechanical properties and stress corrosion cracking would be researched.. Grain size of fibers was about 1~5μm. When the strain rate was faster, the ultimate tensile strength (UTS) would be higher and the ultimate tensile strength (UTS) could reach more than 900MPa. For stress corrosion cracking (SCC), dilute hydrochloric acid was used and the concentration were 0.6M, 0.8M, 1.6M；meanwhile, the failure time was different as the stress was changed. While the solution concentration was 0.6M or 1.6M, the curve of stress v.s failure time showed a linear tendency, but the nonlinear result was obtained from 0.8M. In higher temperature (40℃, 50℃), failure time were shorter because of higher reaction rate. Scanning electron microscopy (SEM) was used to investigate the fracture surface after tensile and SCC tests.