In heat-transfer plates, independently of the type of steel, corrosion pits appear mainly at the tops of corrugations (at the sites of minimum gaps between the adjacent plates). The role of sites of their initiation is played by nonmetallic inclusions of complex oxides (Al, Si, Ti, and Mg) and oxysulfides (Ti and Ca). It is experimentally established that the deformation of heat-transfer plates has almost no influence on the corrosion losses in the course of the tests carried out in chloride-containing media. The process of stable depassivation and development of pitting runs near nonmetallic inclusions of a certain type. In chloride-containing solutions without oxidizers, the pits are initiated near oxides and oxysulfide nonmetallic inclusions, whereas in chloride-containing solutions with oxidizers, they are initiated near oxysulfide and nitride inclusions.