Controlling Variability in Mechanical Properties of Plates by Reducing Centerline Segregation to Meet Strain-Based Design of Pipeline Steel

Abstract

Low variability in mechanical properties is required for pipeline project designs to meet a strain-based design, which is used in regions of large ground movements. The objective of this study is to elucidate the influence of centerline segregation in continuously cast slab on variability in the mechanical property of pipeline steel, and controlling centerline segregation can meet the requirements of a strain-based design. Mannesmann rating method was used to evaluate the degree of segregation of two slabs and its effect on variability in mechanical properties of corresponding plates. Microstructural characterization indicated that bainite/martensite was formed in a segregated area where the content of C and Mn enriched. The mechanical property results indicated that controlling the degree of centerline segregation can reduce tensile strength variability and improve ductile-brittle transition temperature (DBTT).

A comprehensive quantitative characterisation of the multiphase microstructure of a thick-section high strength steel

“…Such elemental variation in the mid-thickness are reported to affect phase transformation temperatures (e.g. bainite and martensite start temperature) and may lead to different microstructural compositions in the centreline segregation bands compared to the depleted areas and also within the bands at the same cooling rate [35][36][37].…”

High-Strength Low-Alloy Steels

“…Jiménez-Peña et al [15] compared the fatigue response of high-strength low-alloy plates with holes manufactured by five processes, namely punching, drilling, waterjet-cut, plasma, and laser-cut. Guo et al [16] evaluated the variability in the mechanical properties of pipeline steel associated with the centreline segregation in continuously cast slab to meet the requirements of strain-based design.Ślęzak [17] studied the fatigue crack initiation and fatigue crack growth in welded joints made of S960QL high-strength low-alloy steel subjected to straincontrolled conditions. Harun et al [18] analysed the effect of the localized wall thinning on low-cycle fatigue resistance of elbows, with artificially introduced defects, made of C70600 steel from full-scale tests.…”

High-Strength Low-Alloy Steels

“…Jiménez-Peña et al [15] compared the fatigue response of high-strength low-alloy plates with holes manufactured by five processes, namely punching, drilling, waterjet-cut, plasma, and laser-cut. Guo et al [16] evaluated the variability in the mechanical properties of pipeline steel associated with the centreline segregation in continuously cast slab to meet the requirements of strain-based design. Ślęzak [17] studied the fatigue crack initiation and fatigue crack growth in welded joints made of S960QL high-strength low-alloy steel subjected to straincontrolled conditions.…”