Masaaki Sugiyama

X100 Linepipe With Excellent HAZ Toughness and Deformability

Good low-temperature toughness of the base material (BM) and weld heat-affected zone (HAZ), and good deformability of the pipe body together with good field weldability are required for X100 linepipe to ensure the safety of pipelines and to facilitate field welding. It is, however, very difficult to attain these properties simultaneously because of the large addition of alloys. The technology of improving HAZ toughness by reducing carbon content through the reduction of M-A constituents harmful to low-temperature toughness was developed, and accelerated cooling after controlled rolling was applied to attain good low-temperature toughness of BM and high uniform elongation together with sufficient strength corresponding to X100. Two newly developed types of X100 linepipe, a “high HAZ toughness type” and a “high uniform elongation type”, exhibited excellent low-temperature toughness of the HAZ and high uniform elongation together with sufficient strength, respectively.Copyright

Development and Properties of Ultra-High Strength UOE Linepipe

High-pressure operation through high strength linepipe reduces long distance transportation cost of natural gas. In order to maximize the cost reduction, X120 UOE pipe has been developed. Low C-Mo-B steel with fine-grained lower bainite (LB) microstructure realizes high strength, excellent low temperature toughness and good weldability. The technology was verified in small-scale commercial production or “mini-rolls”. Suitability for use as linepipe was demonstrated through an extensive development program that covers burst test, fracture toughness evaluation, girth welding technology, etc. A demonstration line was successfully constructed using the pipes manufactured in the “mini-rolls”.Copyright

X120 UOE Linepipe With Improved Properties and Varied Sizes

Nippon Steel has developed X120 UOE linepipe as a part of joint development program with ExxonMobil. After establishment of the basic production technology of X120, the mechanical properties have been improved, especially to increase the suitability to strain based design application and the size range has been expanded. The combination of heavily deformed austenite grains and a mild accelerated cooling to lower cooling stop temperatures (MAC) achieves the aim to lower the yield strength (YS) and the yield to tensile (Y/T) ratio for the B-containing chemistry that was decided to meet the CG-HAZ toughness target. The properties of MAC pipes met the targets and the pipes with OD from 28” to 48” and WT from 13mm to 20mm were made for test purpose.Copyright

Roles of Copper and Nickel in 13%Cr Stainless Steel for Improvement of Wet Carbon Dioxide Corrosion Resistance

Abstract Resistance to hydrogen sulfide (H2S) and carbon dioxide (CO2) corrosion in 13%Cr stainless steel (SS) has been studied to develop a new material in an application field of oil country tubular goods (OCTG). Recently, the combined addition of copper and nickel was found to increase the corrosion resistance of 13%Cr SS under wet, high-temperature, and CO2 environments. The purpose of the present work was to make clear the role of such copper and nickel elements as additive elements to the 13%Cr SS. With the increase in the addition of copper and nickel to the steel, a thickness of corrosion film growing in the immersion test decreased drastically, and the corrosion rate reached < 0.1 mm/y, even at 200°C. The transmission electron microscope analysis revealed that the thin corrosion film was an amorphous phase, and that the addition of copper caused the change of the corrosion film structure from a spinel crystalline to the amorphous one. Nano-ordered segregation of copper at the interface between th...

Importance of Controlling Microstructure Heterogeneity when Designing Steel

Steel has been used since long in the past, but there still remain many unexplored possibilities. In order to draw out this latent potential, the concept of materials integration is garnering attention in view of discontinuously improving the function and performance of steel products, while reducing the necessary development period. In this paper, considering the utilization of materials integration, the evolution of the microstructure during plastic deformation and phase transformation as well as controlling hydrogen embrittlement are discussed in terms of heterogeneity. In addition, a brief outlook on the future of materials integration is presented.