scispace - formally typeset
Search or ask a question
Topic

Microalloyed steel

About: Microalloyed steel is a research topic. Over the lifetime, 2183 publications have been published within this topic receiving 33586 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, a low-carbon microalloyed steel containing high Ni and Cu content has been developed and subjected to thermo-mechanical processing by varying the finish rolling temperature (FRT∼850-750 °C) and cooling rates (air cooling and water quenching).
Abstract: A low-carbon microalloyed steel containing high Ni and Cu content has been developed and subjected to thermo-mechanical processing by varying the finish rolling temperature (FRT∼850–750 °C) and cooling rates (air cooling and water quenching). Microstructures of air cooled samples consist of granular bainite and lath or plate-like bainite, whereas, water quenched samples exhibit a mixture of lower bainite and lath martensite. A refinement in microstructure has been noticed with the decrease in FRT and increase in cooling rate. Transmission electron microscopy demonstrates the presence of coarse (Ti, Nb)C precipitates (~90–160 nm) and fine Cu precipitates (<20 nm). Macro-texture and micro-texture results reveal the dominance of Goss and rotated Goss texture components, which strengthened with the decrease in FRT and increase in cooling rate. The proposed steel composition and TMCP schedule have offered YS ∼ 1000 MPa, UTS ∼ 1400 MPa, total elongation greater than 10% maintaining a low YS: UTS ratio (0.68–0.80). Such a satisfactory combination of tensile properties achieved in as-cooled or as-quenched conditions (without the need of any tempering treatment) makes the steel suitable for automotive application.

31 citations

Journal ArticleDOI
22 Feb 2017
TL;DR: In this article, a detailed characterization of the microstructural features of three different microalloyed steels, Nb, nb-Mo and Ti-Mo, is described using mainly the electron backscattered diffraction technique (EBSD) as well as transmission electron microscopy (TEM).
Abstract: Low carbon microalloyed steels show interesting commercial possibilities by combining different “micro”-alloying elements when high strength and low temperature toughness properties are required. Depending on the elements chosen for the chemistry design, the mechanisms controlling the strengths and toughness may differ. In this paper, a detailed characterization of the microstructural features of three different microalloyed steels, Nb, Nb-Mo and Ti-Mo, is described using mainly the electron backscattered diffraction technique (EBSD) as well as transmission electron microscopy (TEM). The contribution of different strengthening mechanisms to yield strength and impact toughness is evaluated, and its relative weight is computed for different coiling temperatures. Grain refinement is shown to be the most effective mechanism for controlling both mechanical properties. As yield strength increases, the relative contribution of precipitation strengthening increases, and this factor is especially important in the Ti-Mo microalloyed steel where different combinations of interphase and random precipitation are detected depending on the coiling temperature. In addition to average grain size values, microstructural heterogeneity is considered in order to propose a new equation for predicting ductile–brittle transition temperature (DBTT). This equation considers the wide range of microstructures analyzed as well as the increase in the transition temperature related to precipitation strengthening.

31 citations

Journal ArticleDOI
TL;DR: In this paper, different hot rolling simulation techniques, testing schedules and types of analysis were used to determine the recrystallization kinetics of a microalloyed steel, and good agreement was found between the results from different test equipment for the double deformations tests.
Abstract: A high amount of deformation below the non-recrystallization temperature (T-nr) is a common industrial practice to achieve a good combination of toughness and strength in microalloyed steels. To combine the industrially relevant optimum combination of high productivity and product quality, an accurate knowledge of T-nr and the recrystallization kinetics is required. Although a lot of literature data is available on the recrystallization behaviour of microalloyed steels, correlations are often difficult to be made due to the effect of different experimental setups, types of analysis and test schedules that are used to obtain this data. Although this would significantly improve the knowledge about these steels, so far, no systematic comparison has been presented in literature to correlate the different techniques and methods. In this study, different hot rolling simulation techniques, testing schedules and types of analysis were used to determine the recrystallization kinetics of a microalloyed steel. On the one hand, good agreement was found between the results from different test equipment for the double deformations tests. On the other hand, stress relaxation tests showed accelerated kinetics and appeared to be less effective.

31 citations

Journal ArticleDOI
F. J. Ma1, G. H. Wen1, P. Tang1, X. Yu1, Jiangling Li1, G. D. Xu, F. Mei 
TL;DR: In this paper, the authors investigated the causes of transverse corner cracks in some microalloyed steels produced on some vertical bending type continuous slab casters and found that the cracks are usually found on the fixed (outer) side corner of the slabs through inspection of the acid pickled surface and macroscopic examination.
Abstract: Transverse corner cracks have been frequently observed and are extremely difficult to prevent in some microalloyed steels produced on some vertical bending type continuous slab casters. The cracks are usually found on the fixed (outer) side corner of the slabs through inspection of the acid pickled surface and macroscopic examination. In the present study, the slab surface microstructure was investigated, and the results show that the causes of the crack formation are chain-like precipitations and film-like proeutectoid ferrite in the austenite grain boundaries when the slabs are bent. Initially, when the temperature of the slabs dropped after solidification, the Nb, V or Ti carbides and/or nitrides precipitated in chain-like way, then pinned onto the austenite grain boundaries. This process hindered grain boundary slippage and lowered the force on the grain boundaries. Second, due to the stress mismatch between the matrix and the fine precipitates during bending operations, the chain-like precipi...

31 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the effect of hydrogen on the properties of the passive film on X70 microalloyed steel and found that hydrogen increases the capacitance and donor density, and decreases the flatband potential and the space-charge layer thickness of passive film.
Abstract: It has been reported that hydrogen decreases the stability of the passive films on iron and stainless steel and promotes their localized corrosion. However, the mechanism of hydrogen-promoted corrosion is still not clear. Potentiostatic, electrical impedance spectroscopy measurements, and Mott-Schottky analysis were used to investigate the effect of hydrogen on the properties of the passive film on X70 microalloyed steel. In the range of passive potentials, hydrogen retards the passive film formation and decreases its stability. Impedance spectra of passive film on X70 steel show that hydrogen decreases the resistance towards charge transfer and ion diffusion and increases the capacitance of the passive film. Mott-Schottky analyses show that hydrogen increases the capacitance and donor density, and decreases the flatband potential and the space-charge layer thickness of the passive film. A new explanation is proposed for the effects of hydrogen on the properties of the passive films. According to this explanation, hydrogen creates an additional electric repulsion on Fe 2+ or Fe 3+ and oxygen vacancies, and enhances the diffusion rate of cations and anion vacancies. At steady state, hydrogen will not only decrease the concentrations of O 2- and Fe 3+ , but also increase the concentration of Fe 2+ in the passive films, resulting in changes in the structure and a decrease in the thickness of the passive films.

31 citations


Network Information
Related Topics (5)
Alloy
171.8K papers, 1.7M citations
84% related
Microstructure
148.6K papers, 2.2M citations
84% related
Deformation (engineering)
41.5K papers, 899.7K citations
82% related
Grain boundary
70.1K papers, 1.5M citations
81% related
Welding
206.5K papers, 1.1M citations
79% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202328
202288
202164
202090
201986
201888