76 Y Gong, Z-G Yang/ Materials and Design 32 (2011)671-681 a。下 corrosion produets etallographic structures of the fractured inlet tube (a)100x and (b) polished state 200x. 31/TY/7 5E 00010020030040050060070800 0m1002003m40050607m8m Fig. 11. Morphologies and EDS of the cross-section of the fractured inlet tube(a)macroscopic morphology, (b)SEM micrograph, (c) EDS of site A and (d)EDS of site B. reached 50-500 um. Then micro-area chemical compo in site b was the existence of the sulfur element, whose content of the two sites marked as a(matrix metal )and b(corrosion was 5.21% Thus, it can be inferred now that the sulfur related cor- cts) in Fig. 11b were detected by EDS, and the results were rosion may have been mainly blamed for the fracture of the inlet in Fig. 11c and d and Table 2. The most obvious characteristic tube and further discussion is needed to determine its causes Ind mechanisms Chemical compositions of site A and B(wt%). 3. 2. Manhole doors ement C Cr Fe Inspection 08130.1345.7610.6 16.559520.891582263425.675.21 Chenical mma ositions of the matrix metals of the two manhole in table 3. which are in accordance with theready reached 50–500 lm. Then micro-area chemical composi￾tions of the two sites marked as A (matrix metal) and B (corrosion products) in Fig. 11b were detected by EDS, and the results were listed in Fig. 11c and d and Table 2. The most obvious characteristic in site B was the existence of the sulfur element, whose content was 5.21%. Thus, it can be inferred now that the sulfur related cor￾rosion may have been mainly blamed for the fracture of the inlet tube, and further discussion is needed to determine its causes and mechanisms. 3.2. Manhole doors 3.2.1. Matrix metal inspection Chemical compositions of the matrix metals of the two manhole doors are listed in Table 3, which are in accordance with the Fig. 10. Metallographic structures of the fractured inlet tube (a) 100 and (b) polished state 200. Fig. 11. Morphologies and EDS of the cross-section of the fractured inlet tube (a) macroscopic morphology, (b) SEM micrograph, (c) EDS of site A and (d) EDS of site B. Table 2 Chemical compositions of site A and B (wt.%). Element C O Si Cr Fe Ni S Site A 12.49 / 0.81 30.13 45.76 10.61 / Site B 16.55 9.52 0.89 15.82 26.34 25.67 5.21 676 Y. Gong, Z.-G. Yang / Materials and Design 32 (2011) 671–681