Effect of Heat Treatment Before and After Incremental Rolling on the Mechanical Properties of Titanium-Stabilized Austenitic Stainless Steel

Abstract

Austenitic stainless steel 08Ch18N10T stabilised with titanium is used for parts of VVER nuclear power reactors. The final mechanical properties are strongly affected by the previous processing history. This is mainly due to the deformation hardening that is incorporated into the material during the production of semi-finished products. The experimental program was performed on 08Ch18N10T steel bars with a diameter of 30 mm. Incremental rolling was performed on bars that remained in the delivered condition and on bars subjected to solution annealing at 1020 °C for 60 minutes before rolling. The rolled bars were stabilised annealed at different temperatures. Then a metallographic evaluation and a tensile test at RT and 350 °C were performed. The results show that the rolling speed significantly affects the mechanical properties after stabilisation annealing. By reducing the rolling speed, it was possible in some cases to increase the yield strength up to 349 MPa. The stabilisation annealing temperature of 720 ° C with a holding time of 10 hours was evaluated as the most advantageous. In the case of higher stabilisation annealing temperatures, the lowest rolling speed, i.e. 25 rpm, had to be performed to achieve higher hot yield strength values exceeding 177 MPa.