Method of testing the long-term strength of clad steels in corrosion-active media

Clad materials in which the substrate is represented by a carbon or low-alloy steel and the cladding layer is in the form a high-alloy steel are used to save very scarce corrosion-resisting materials. A method has been developed of examining the long-term strength of clad steels in corrosion-active media at high temperatures and pressures. The experimental setup provides provisions for pressurizing, heating, temperature measurement and stress measurement. The results show that the long-term strength of the clad specimens in hydrogen is higher than the strength of unprotected steel 20 in air at the same temperature. The metallographic examination of the clad specimens after testing for long-term strength at 500/sup 0/C and a hydrogen pressure of 58.8 MPa shows that at the ratio of the thicknesses of the cladding to main layers of 1:4 hydrogen has no effect on steel 20; however, surface decarburization of the main layer takes place at a ratio of 1:9. The specimens may be made of metals of almost any combination and any ratio of the thickness of the cladding to main layers.