Corrosion Behaviour of Stainless Steel and its Weld in High Temperature Sodium Under Tensile Stress

It is well known that the main corrosion types of LMFBR cladding in high temperature sodium are of uniform corrosion, intergranular corrosion, selection solution of composition elements and mass transfer effect [1–4]. On the other hand, the cladding of fuel pins suffers many kinds of stress, such as mechanical interaction between fuel and cladding due to the difference in thermal-expansion when power changes and reactor restart; increasing of internal pressure of cladding with fission products release, and so on. For the weld, the chemical-metallurgical process caused by heating and cooling rather quickly will occur in the welding seam, and the heating effect and residual stress will appear in it. The corrosion, creep, and tensile behaviour of weld in sodium have been studied [4–7]. Its corrosion behaviour is different obviously from those of the material itself. Therefore, the investigation of the corrosion behaviour of cladding materials, especially their weld, in high temperature sodium under tensile stress is rather important for the development of FBR fuel cladding material.