The effect of sulfide inclusions on the susceptibility of steels to pitting,stress corrosion cracking and hydrogen embrittlement

Recent opinions on the effect of nonmetallic inclusions, especially sulfides, on the nucleation of pits, stress corrosion cracks, and hydrogen-induced cracks are reviewed. The nonmetallic inclusions present in steels as impurities adversely affect the corrosion resistance of steels. This is true for both the general and local corrosion mechanisms, like pitting corrosion, stress corrosion cracking (SCC), and hydrogen embrittlement (HE). The effect of nonmetallic inclusions (in particular that of sulfides) on the pitting corrosion mechanism has been the subject of numerous investigations. A fairly aboundant information can be found in vast original literature and in many review articles [1–3]. The role of nonmetallic inclusions in SCC is relatively less covered in the pertinent literature. Since, however, the nucleation of corrosion cracks frequently starts from pits, and pits nucleate at sulfides, the presence of sulfides is likely to affect the SCC process. Another corrosion mechanism that leads to a local cracking of a metal is the hydrogen embrittlement. The presence of nonmetallic inclusions enhances susceptibility of steel to hydrogen-induced cracking [4]. This review will be concerned with the effect of nonmetallic inclusions on the local corrosion types mentioned.