Enhancing the ductility of ferritic/martensitic stainless steel through the use of PM HIP manufacturing techniques

• Fracture of the fuel cladding tubes fabricated by PM HIP and conventional techniques were investigated.
• The ring tensile test method was used to determine the mechanical properties.
• The different fracture modes of the specimens fabricated by above mentioned techniques were observed.
• The thermal aging of cladding tubes was performed at 600 and 700 °C for 1400 and 1000 h.
• The advantage of the cladding tubes properties fabricated by PM HIP was found to retain after thermal aging.

In this work, comparative tensile tests of ferritic/martensitic stainless steel cladding tube specimens and an investigation of the microstructure, fracture mode, carbon and boron distribution were performed in the specimens of cladding tubes and semi-products manufactured using powder metallurgy via hot isostatic pressing of rapidly quenched powder (PM HIP) and in specimens made using conventional technology. A multi-scale investigation of the carbon and boron distribution was performed using direct high-sensitivity autoradiography methods. Additionally, a multi-scale structure investigation using metallography and other methods, such as scanning electron microscopy and X-ray spectral microanalysis, was carried out. Enhanced ductility of the cladding tubes manufactured using the PM HIP technique was observed compared with the cladding tubes produced using conventional technology. This enhancement was attributed to the change in the fracture mode under tension. Greater homogeneity of the carbon and boron distribution in addition to a greater dispersion of the microstructure in the specimens produced using the PM HIP technique was detected.