6. JQ2 sample
6.1. IGSCC observations on cross -section
The loading procedure for JQ2 was aimed at producing longer cracks. As shown in Fig. 11, the cracks at the cross section were longer than that in JQ1. Fig. 11 shows that the crack can branch along different grain boundaries at an early stage. Fig. 11(c) and (d) shows wider cracks;these are interpreted as having been opened due to overload at the end of the SCC test.
6.2. Fracture surface of JQ2
An overview of the fracture surface is shown in Fig. 12. Location ‘‘A’’ is the original surface. Locations B, C, D are the fracture surface. Location E is the electropolished surface. Location F is a crack at the edge of the specimen. The high-magnification observation at different locations indicated as follows. Location ‘‘A’’ showed an oxide-covered surface. Most of locations B, C & D showed dimple rupture indicative of a ductile fracture process.
 

Fig. 9. IGSCC at surface grew along ferrite grain boundaries.