Effects of Mo, Cr, and V Additions on Tensile and Charpy Impact Properties of API X80 Pipeline Steels

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 40; no. 8; pp. 1851 - 1862
• Main Authors: Han, Seung Youb, Shin, Sang Yong, Seo, Chang-Hyo, Lee, Hakcheol, Bae, Jin-Ho, Kim, Kisoo, Lee, Sunghak, Kim, Nack J.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01-08-2009; Springer; Springer Nature B.V
• Subjects: Alloys; Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Crack propagation; Exact sciences and technology; Fractures; Grain boundaries; Impact tests; Materials Science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metallic Materials; Metallurgy; Metals. Metallurgy; Nanotechnology; Regression analysis; Structural Materials; Studies; Surfaces and Interfaces; Thin Films; Acicular Ferrite; Charpy Impact; Finish Cool Temperature; Pipeline Steel; Granular Bainite; Oil industry; Microalloyed steel; Rupture; Mechanical properties; Carbon steel; Tensile property; Application; Impact test; Pipeline
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-009-9884-3

In this study, four API X80 pipeline steels were fabricated by varying Mo, Cr, and V additions, and their microstructures and crystallographic orientations were analyzed to investigate the effects of their alloying compositions on tensile properties and Charpy impact properties. Because additions of Mo and V promoted the formation of fine acicular ferrite (AF) and granular bainite (GB) while prohibiting the formation of coarse GB, they increased the strength and upper-shelf energy (USE) and decreased the energy transition temperature (ETT). The addition of Cr promoted the formation of coarse GB and hard secondary phases, thereby leading to an increased effective grain size, ETT, and strength, and a decreased USE. The addition of V resulted in a higher strength, a higher USE, a smaller effective grain size, and a lower ETT, because it promoted the formation of fine and homogeneous of AF and GB. The steel that contains 0.3 wt pct Mo and 0.06 wt pct V without Cr had the highest USE and the lowest ETT, because its microstructure was composed of fine AF and GB while its maintained excellent tensile properties.