While much progress has been made toward understanding stress-corrosion cracking (SCC) of line-pipe steels, a number of unresolved issues merit further research. Even under well-controlled conditions in the laboratory, crack growth rate varies considerably with time, and many cracks appear to become dormant. Determining the reasons for dormancy and reactivation of dormant cracks is critical to life prediction. In high-pH environments, the threshold stress for SCC has been related to cyclic strain-hardening behavior. The relationship between cyclic strain-hardening behavior and microstructure as affected by steel composition and processing would foster the development of SCC-resistant steels. Whether the same relationship holds for near-neutral-pH SCC also should be determined. While hydrogen
appears to be important for near- neutral-pH SCC, its role has not been explained, nor is the role of dissolution clearly understood. Recommendations for research to address those issues are offered along with some thoughts about the mechanisms of initiation and growth in near-neutral-pH SCC.