大型渗碳炉用CrNiNRE耐热钢辐射管的失效机理研究　　

Failure Mechanism Analysis of Radiant Tube of CrNiNRE Heat Resistant Steel for Carburizing Furnaces

应用SEM电镜、能谱分析及X射线衍射等方法研究了高镍铬含氮和稀土的奥氏体型CrNiNRE耐热钢辐射管在长期高温渗碳中的失效机理和组织特征。结果表明,CrNiNRE钢在长期高温和单边渗碳作用下,使得M7C3碳化物持续长大,并促使奥氏体区域退缩和沿碳化物周边形成裂隙;合金元素的重新分布造成基体贫铬;管内壁氧的侵入形成氧化空洞和疏松;这些因素的综合作用导致构件最终贯通穿孔而失效。

By means of SEM analysis, EDS and X-ray diffraction, the failure mechanism and the microstructure of the radiant tube for carburizing furnace made of austenite heat-resisting cast steel CrNiNRE containing high Cr, Ni and RE in the long-term and high temperature carburizing environment were investigated and analyzed. The results indicate that the long-term high temperature unilateral carburizing makes the M7C3 carbide grow up perfectly, and promote the austenite region diminished and form crack around the carbide. The re-distribution of alloying elements results in chromium dilution in the austenitic matrix. The oxygen invasion in inside wall of the tube results in the interior porous and the oxidized cavity. These factors synthetically cause the tube failure finally by opening into one another.