Isochronal Phase Transformations of Low‐Carbon High Strength Low Alloy Steel upon Continuous Cooling

Abstract

Aimed to acquire optimum comprehensive properties for the oil and gas pipeline steels, thermal treatment should be controlled to achieve ideal microstructures. Effects of cooling rates on transformation kinetics and microstructures of the low-carbon high strength low alloy (HSLA) steel were investigated to obtain an optimized thermal treatment technology. Dilatometric measurements, light microscopy, scanning electron microscopy, and transmission electron microscopy were employed in present work. The transformed microstructures contained polygonal ferrite þ pearlite, acicular ferrite (AF), and bainitic ferrite (BF) due to the cooling rates increasing from 5 to 30008C min À1 , in present investigated HSLA steel. The result shows that, the increase of cooling rate accelerates AF transformation and refines the steel's matrix. The morphology of martensite/austenite structures transformed from islands in AF to films in BF with the increase of cooling rate.

Effect of microstructure variation on the corrosion behavior of high-strength low-alloy steel in 3.5wt% NaCl solution

“…3(f) are distributed within the martensite matrix. According to previous studies, these precipitates can effectively pin the dislocation and stabilize the substructure [18]; thus, the Vickers hardness is the highest. …”

Kinetics of the austenitization in the Fe-Mo-C ternary alloys during continuous heating

“…The optical microscopy was employed to study the structures. The statistics for the size of the austenite grain were obtained through the line-intercept method in the optical micrographs [20]. Fig.…”

Effect of Bainitic Packet Size Distribution on Impact Toughness and its Scattering in the Ductile-Brittle Transition Temperature Region of Q&T Mn-Ni-Mo Bainitic Steels

“…[1,2] Preventing their brittle failure at low temperature and high pressure is an important issue because their service temperature are usually as low as -45 to -60 8C, which may fall in the ductile-brittle transition temperature (DBTT) region. Besides dramatically varying upon small temperature change, the toughness in the DBTT region also shows large scattering from one sample to another at the same temperature.…”

“…High‐strength low‐alloy bainitic steels are widely used in manufacturing cryogenic pressure vessel components . Preventing their brittle failure at low temperature and high pressure is an important issue because their service temperature are usually as low as –45 to –60 °C, which may fall in the ductile–brittle transition temperature (DBTT) region.…”