Understanding mechanical property anisotropy in high strength niobium-microalloyed linepipe steels

Effects of specimen geometry and anisotropic material response on the tensile strain capacity of flawed spiral welded pipes

“…Linepipe steel is known to be anisotropic with respect to not only yield strength but also work hardening, ductility and toughness [32][33][34][35][36][37]. A numerical implementation of all aspects requires highly advanced material definitions.…”

Relationships among crystallographic texture, fracture behavior and Charpy impact toughness in API X100 pipeline steel

“…To improve the pipeline transport efficiency, large diameter, high pressure [1] and long distance transmission pipelines become a trend in the development of pipeline steels. It strongly requires pipeline steels to obtain a good combination of high strength and excellent toughness [2].…”

“…Alloying elements such as Mn, Nb, V, Ti, Cu, Ni, Mo and Cr are commonly employed in pipeline steels so as to obtain the desired mechanical properties. For example, the numbers of alloying elements are reduced to attain low carbon equivalent (CE) in order to ensure good weldability [1]. In addition, alloying elements such as Cr, Cu, and Ni are added to obtain strength in the severe corrosive environment [5].…”

Microstructure and microtexture assessment of delamination phenomena in charpy impact tested specimens

“…The combination of high strength and toughness allows an increase in the transmission capacity by operation at duct in high pressures. The increase in resistance allows a significant reduction in thickness, with a consequent reduction in weight, and contributes to improving the fracture toughness, which tends to decrease with the thickness increasing 1,2 . The thermomechanical process is mainly responsible for the increasing resistance, and consequently, for the reduction in thickness.…”

“…This anisotropy is attributed to the presence of inclusions, anisotropic microstructure, crystallographic texture, the presence of inclusions such as manganese sulfide, which tend to become stretched during rolling, and pearlite bands resulting from chemical segregation in the solidification process. With respect to texture, these steels tend to develop a strong fiber texture during controlled rolling, involving deformation, recrystallization and phases transformation 2,3 . With regard to the fracture process by impact test, these steels exhibit the phenomenon known as delamination, whose occurrence can be attributed to crystallographic texture, intergranular fracture along grain boundaries of retained austenite, segregation of elements such as phosphorus and sulfur, microstructural anisotropy, banding, inclusions and aligned particles 3 .…”