The effect of Al and Nb contents, cooling rate and rolling condition on the microstructure and corrosion behaviour of HSLA steel

Abstract

The effect of the addition of aluminium and niobium, and processing conditions, including cooling rate and rolling condition, on the corrosion behaviour of HSLA steel in 10 wt% sulphuric acid environment has been investigated. The experimental procedures included electrochemical corrosion techniques using potentiodynamic and electrochemical impedance spectroscopy, as well as weight loss method. The microstructure was examined using optical and scanning electron microscopes in order to investigate the effect of the microstructural features on the corrosion behaviour. Surface films were evaluated by X-ray photoelectron spectroscopy (XPS) to identify the corrosion products formed on the surface. The results showed that increasing the Al content enhanced the corrosion resistance through obstructing pitting attack on the surface by the refinement of grain boundary carbides and the formation of a protective passive layer rich in carbide and oxide compounds. The combination of both Al and Nb promoted the corrosion resistance further, by enriching the passive layer with Nb and higher levels of carbide and oxide compounds, despite the presence of martensite and grain size refinement by niobium carbonitride (NbCN). Increasing the cooling rate reduced the corrosion resistance due to the refinement of grain size, giving a higher density of grain boundaries that act as active sites, besides increasing the level of carbide distribution in the microstructure. Controlled rolling offered higher corrosion resistance than hot rolling, independent of the composition, because of the absence of martensite, the presence of lowangle boundary and the refinement of grain boundary carbides provided by controlled rolling.

Effect of Cooling Mode on the Microstructure of High-Strength Steel during Hot Rolling

“…The results show that the effective grain size obtained by the cooling method in process 1 has a remarkable refining effect, which is beneficial to improve the comprehensive properties of materials. This is more consistent with Abdullah's [16] findings. In order to characterize the effect of the cooling process on the structure grain size, EBSD (Bruker, Saarbrucken, Germany) is used to analyze the effective grain size, as shown in Figure 7.…”

“…The results show that the effective grain size obtained by the cooling method in process 1 has a remarkable refining effect, which is beneficial to improve the comprehensive properties of materials. This is more consistent with Abdullah's [16] findings. The ferrite proportion in industrial test results is consistent with that in the laboratory simulation results, but the grain size and the uniformity of the structure are quite different, which is related to the sample size during the actual industrial production and the holding time after coiling.…”

“…How to ensure that the coil collapse does not occur under the higher coiling temperature is one of the core production technologies to guarantee the batch and stable production of high-strength steel [14]. According to some literature research [15][16][17], the effect of the cooling process on microstructure and phase transition is studied in this paper, and the way to reduce the coil collapse defect by improving the cooling mode is put forward and is applied in the practical production, which obtains a better effect. The research theory also has strong reference significance for improving other high-strength steel products.…”

An Overview of Laser Welding of High Strength Steels for Automotive Application

“…ADVANCED HIGH STAINLESS STEEL HSS is a solid solution, precipitation or grain grinding hardens, while Advance High Stainless Steel is hardened by phase-processing. The chemical compositions are carefully selected and multiphase microstructures are controlled by the heating and cooling process to form the unique combination of material and mechanical properties of AHSS grades [35]. AHSS has superior strength and more ductile in comparison to HSS.…”

Study on Microstructure and Mechanical Properties of Marine 10Ni5CrMoV Steel during Tempering

“…High strength low alloy (HSLA) steels are widely used in various fields such as construction machinery, offshore platforms, and ship plates due to their excellent combination of strength and toughness. [1][2][3] In response to the growing demand for exploring deep-sea resources, research on marine materials worldwide is increasingly focused on achieving high strength and high toughness, particularly at cryogenic temperatures. [4][5][6] In general, the high strength of steel often results in limited impact toughness, especially at low temperatures, which restricts the application of high-strength steel in specific fields.…”