Microalloyed Steels through History until 2018: Review of Chemical Composition, Processing and Hydrogen Service

Abstract

Microalloyed steels have evolved in terms of their chemical composition, processing, and metallurgical characteristics since the beginning of the 20th century in the function of fabrication costs and mechanical properties required to obtain high-performance materials needed to accommodate for the growing demands of gas and hydrocarbons transport. As a result of this, microalloyed steels present a good combination of high strength and ductility obtained through the addition of microalloying elements, thermomechanical processing, and controlled cooling, processes capable of producing complex microstructures that improve the mechanical properties of steels. These controlled microstructures can be severely affected and result in catastrophic failures, due to the atomic hydrogen diffusion that occurs during the corrosion process of pipeline steel. Recently, a martensite-bainite microstructure with acicular ferrite has been chosen as a viable candidate to be used in environments with the presence of hydrogen. The aim of this review is to summarize the main changes of chemical composition, processing techniques, and the evolution of the mechanical properties throughout recent history on the use of microalloying in high strength low alloy steels, as well as the effects of hydrogen in newly created pipelines, examining the causes behind the mechanisms of hydrogen embrittlement in these steels.

Advances in Microalloyed Steels

“…The present Special Issue on Advances in Microalloyed Steels includes two review papers [1,2] and nine research papers [3][4][5][6][7][8][9][10][11]. In all of them, different combinations of microalloying elements are analyzed in terms of process, microstructure, and mechanical property modification.…”

“…The alternatives in microalloying are clearly reflected in terms of the grades studied in the different papers. Nb is present in many of them [1,2,5,7,8,10,11], alone or in combination with Mo [2,5,10], Ti [8], and V [10]. Two papers deal with Ti-Mo combinations [6,9], and the last two articles analyze the addition of V [4] and Al [3] as microalloying elements.…”

“…Even if some papers cover specific performance problems and optimization alternatives for industrial processing conditions [1,2,7,11], most of the papers deal with more fundamental analyses of the relationship between microstructure and mechanical properties [4][5][6]8,10]. Some papers also analyze the effect of microalloying on hot and cold working behaviors [3,9].…”

The Impact of Isothermal Treatment on the Microstructural Evolution and the Precipitation Behavior in High Strength Linepipe Steel

“…High-strength low alloy (HSLA) steels present a good combination of high strength and ductility obtained through the addition of microalloying elements, thermo-mechanical controlled processing (TMCP), and processes capable of producing complex microstructures that improve the mechanical properties of steels [1]. HSLA steels containing niobium and/or titanium as the microalloying elements are widely used for construction, line pipe, pressure vessel, engineering, automobile, naval, and defense applications [2][3][4].…”

Influence of the local degree of deformation on the temperature dependent fatigue behaviour of a ferritic–pearlitic steel

“…In the 1970s, the development of precipitation-hardened ferritic-pearlitic steels began [1][2][3][4] with the aim to use the materials directly from the forging heat to save process costs 2,3 for forged automobile industry parts. Hence, the subsequent heat treatment of quenching and tempering would no longer be necessary.…”