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采用光学显微镜、扫描电镜及其EDS、相分析和XRD等分析方法,研究了Super304H钢焊缝及在不同高温(650℃)持久应力下的组织转变。结果表明,焊态下焊缝组织为奥氏体和析出相,析出相以铌相为主。经过高温持久拉伸后,焊缝组织的耐蚀性降低,析出铌相发生了一定程度的溶解,多呈长条状或块状分布,还出现了一定量的α相和M23C6相。此外,焊缝组织的凝固晶界和凝固亚晶界也在高温持久应力下发生了变化。
The microstructures of the weld of Super304H steel and its microstructure under long-term stress (650 ℃) were investigated by optical microscopy, scanning electron microscopy, EDS, phase analysis and XRD. The results show that the weld microstructure is austenite and precipitated phase, and the precipitated phase is dominated by niobium phase. After high temperature tensile, the corrosion resistance of the weld structure decreases, the precipitation of niobium phase of a certain degree of dissolution, mostly strip or block distribution, also appeared a certain amount of α phase and M23C6 phase. In addition, the solidified grain boundaries and solidified subgrain boundaries of the weld seam also change under long-term stress at high temperature.