Impact Toughness and Fracture Structure about Welded Joints of Low Chromium Nickel Ferritic Stainless Steel Containing Ce/Ti.

In order to improve the impact toughness and reduce inclusion, rare earth element Ce and stable element Ti are added in the low chromium nickel ferritic stainless steel welded joints and heat treatment. The Charpy test and tensile test are carried out and fracture structure are analyzed. The results show that when the ratio of Ce is 0.24% and Ti is 0.72% in welded joints of ferritic stainless steel, the mechanical properties is the best. The impact energy of welded joint is 9.4 times more than the samples without Ce and Ti, the impact toughness is also increased by 123.6% after heat treatment and the tensile strength increases by 41.9% The fracture structure is main ductile fracture and dimple, the shape of dimples is parabolic. The dimple is large and deep, and in the bottom of dimple has second phase particles. There is a few cleavage facets and river patterns in the fracture. After thermal cycling, the number of oxide particles reduce and the second phase particles are refined, so the impact toughness is improved. [ABSTRACT FROM AUTHOR]