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该文以采用9%Cr含B铁素体耐热钢为母材、2.25%Cr为填充金属的接头为对象,研究了高温时效过程对接头中的碳迁移层及其附近区域的影响。研究发现:经高温时效后,接头富碳区中的析出物发生粗化且数量增多,而贫碳区中析出物变化不大,导致贫/富碳层的硬度差异增大。有限元计算结果表明:在接头受载情况下,贫碳区会成为首先破坏的部位,并且高温时效会加剧这种破坏。透射电镜(TEM)结果表明:9%Cr含B钢热影响区(HAZ)中的晶界析出物在时效后粗化不明显,而晶内析出物则发生了明显的粗化,这主要是由于B在晶界聚集并通过占据析出物周围的空位阻碍了析出物粗化。
In this paper, the effects of high temperature aging on the carbon transfer layer and its vicinity in the joints were studied using 9% Cr B-containing ferritic heat-resistant steels as base metal and 2.25% Cr as filler metal joints. The results show that after high temperature aging, the precipitates in the carbon-rich zone of the joints are roughened and the number is increased, while the precipitates in the lean carbon zone are not changed much, resulting in the increase of the hardness difference between the carbon-poor and the carbon-rich layers. Finite element results show that: in the joint load conditions, the carbon-poor areas will be the first to damage the site, and aging will exacerbate this damage. Transmission electron microscopy (TEM) results show that the grain boundary precipitates in the heat-affected zone (HAZ) of 9% Cr B-containing steel are not obviously roughened after aged, while the precipitates in the crystal are obviously roughened mainly Agglomeration of the precipitates is hindered by the aggregation of B at the grain boundaries and by the occupation of vacancies around the precipitates.