scholarly journals New Technology to Produce 1 GPa Low Carbon Microalloyed Steels from Cast Strip

Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 662 ◽  
Author(s):  
Andrii Kostryzhev ◽  
Olexandra Marenych
Keyword(s):  
Mechanical Properties ◽  
Global Economy ◽  
New Technology ◽  
Carbon Steels ◽  
Thin Strip ◽  
Microalloyed Steels ◽  
Accelerated Cooling ◽  
Low Carbon ◽  
Elongation To Failure ◽  
Carbon Microalloyed

Global economy requires steel with further increasing mechanical properties and simultaneously decreasing price. In mass manufacturing three major methods can be used to increase strength: (i) increase microalloying element additions (increases cost), (ii) decrease deformation temperature and (iii) increase cooling rate after high temperature processing (both can be challenging for equipment). Thin strip casting is an effective way to reduce cost as it brings a reduction in number of deformation passes and shortens the production line. However, the mechanical properties can be missed due to insufficient microstructure development. In this article, we investigate a recently proposed technology based on Austenite Conditioning followed by Accelerated Cooling and Warm Deformation (AC2WD). Two low carbon steels microalloyed with either 0.012Ti or 0.1Mo-0.064Nb-0.021Ti (wt.%) were subjected to three processing modifications of the AC2WD-technology with two, one or no deformation of cast microstructure in the austenite temperature field. The Ti- and MoNbTi-steels exhibited 685–765 MPa and 880–950 MPa of the yield stress, 780–840 MPa and 1035–1120 MPa of tensile strength, and 20–30% and 22–24% of elongation to failure, respectively. The nature of strengthening mechanisms associated with the AC2WD-technology is discussed on the basis of detailed microstructure characterisation.

scholarly journals Evolution of Microstructure and Precipitation State During Thermomechanical Processing of a Low Carbon Microalloyed Steel

2012 ◽  
Vol 18 (S5) ◽  
pp. 119-120
Author(s):  
P. Valles ◽  
M. Gómez ◽  
S. F. Medina ◽  
A. Pastor ◽  
O. Vilanova
Keyword(s):  
Mechanical Properties ◽  
Acicular Ferrite ◽  
Thermomechanical Processing ◽  
Transformation Products ◽  
Microalloyed Steels ◽  
Accelerated Cooling ◽  
Low Carbon ◽  
Fine Grained ◽  
Increasing Demand ◽  
Carbon Microalloyed

The increasing demand of sources of energy such as oil and natural gas induces at the steel industry a development on low carbon microalloyed steels for pipeline applications in order to achieve excellent mechanical properties of strength and toughness at a reduced cost. To obtain an adequate fine-grained final structure, the strict control of thermomechanical processing and accelerated cooling is crucial. Depending on the thermomechanical processing conditions and chemical composition, pipeline steels can present different microstructures. Several authors have found that the microstructure of acicular ferrite usually provides an optimum combination of mechanical properties. Higher levels of austenite strengthening before cooling promote a refinement of final microstructure but can also restrict the fraction of low temperature transformation products such as acicular ferrite.

Effect of Cool Deformation on the Mechanical Properties of Low C Microalloyed Steels

2008 ◽  
Author(s):  
Jessica Calvo ◽  
Abdelbaset Elwazri ◽  
Dengqi Bai ◽  
Stephen Yue
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
Thermomechanical Processing ◽  
Carbon Steels ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Strengthening Mechanisms ◽  
Rolling Schedule ◽  
Low Carbon Steels ◽  
Carbon Microalloyed

The application of small amounts of deformation at coiling temperatures, i.e. cool deformation, has been shown to be an effective method to improve the mechanical properties of low carbon microalloyed steels. Improvements are related to the effect of cool deformation on strengthening mechanisms such as precipitation, grain refinement and phase transformation. However, it is not clear to what extent mechanical properties will improve when cool deformation is applied after TMP (Thermomechanical Processing). In this work, cool deformation was applied in torsion after a simulation of an industrial rolling schedule to samples of six experimental low carbon steels containing different amounts of Nb, Cu, Mo and Si. In general, it was found that cool deformation improved the mechanical properties of all the steels, and the extent of these improvements was dependent on the chemical composition.

Effect of the Time between Last Deformation Pass and Accelerated Cooling on the Mechanical Properties in Nb and Nb-Mo Microalloyed Steels

2016 ◽  
Vol 716 ◽  
pp. 281-290
Author(s):  
Gorka Larzabal ◽  
Nerea Isasti ◽  
J.M. Rodriguez-Ibabe ◽  
Isabel Gutiérrez ◽  
P. Uranga
Keyword(s):  
Mechanical Properties ◽  
Charpy Impact ◽  
Holding Time ◽  
Microalloyed Steels ◽  
Accelerated Cooling ◽  
Low Carbon ◽  
Compression Tests ◽  
Electron Backscattered Diffraction ◽  
Microstructural Refinement ◽  
Deformation Pass

The microstructural refinement induced when the holding time between last deformation pass and accelerated cooling is reduced, affects the mechanical properties in low carbon Nb and Nb-Mo microalloyed steels. Plane strain compression tests were performed and mechanical property samples machined in order to quantify this effect using tensile and Charpy impact tests. A complete microstructural characterization was carried out using electron backscattered diffraction (EBSD) measuring unit size distributions and homogeneity of complex microstructures. The synergetic combination of Nb and Mo elements modifies the final microstructures and, therefore, affects the contribution of different strengthening mechanisms, such as substructure, precipitation hardening and dislocation density. Even though strength is not clearly affected by the reduction of the holding time after the last deformation pass, Charpy properties are considerably improved in the case of the Nb steel. The presence of MA islands in the Nb-Mo steel limits the beneficial effect of the microstructural refinement and toughness remains unmodified.

Effect of Nb and V in the Development of Texture and Plastic Strain Ratio in Low Carbon Microalloyed Steels Produced by A.S.T. Technology

2005 ◽  
Vol 500-501 ◽  
pp. 279-286
Author(s):  
Carlo Mapelli ◽  
Roberto Venturini ◽  
Antonio Guindani
Keyword(s):  
Mechanical Properties ◽  
Strain Ratio ◽  
Tensile Tests ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Plastic Strain Ratio ◽  
Steel Technology ◽  
Back Scattering ◽  
Carbon Microalloyed ◽  
Hot Rolled

The effects of Nb and V on the anisotropy and textures featuring the hot rolled low carbon microalloyed steels produced by A.S.T. (Arvedi Steel Technology) have been studied as a function of the final coiling temperatute Tcoiling. Mechanical properties and r-values for twelve steels have been determined through tensile tests performed on three main different directions: 0°, 45°, 90° to the rolling one. The samples have been analysed by EBSD (Electron Back Scattering Diffraction) to identify the textures developed during the process. The relations among the chemical composition of the steels (i.e. C, N, Nb, V contents), the mechanical properties, the temperature during the coiling operations, the textures and the formability properties have been pointed out.

scholarly journals Effect of the Chemical Composition on the Structural State and Mechanical Properties of Complex Microalloyed Steels of the Ferritic Class

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 646 ◽  
Author(s):  
Alexander Zaitsev ◽  
Anton Koldaev ◽  
Nataliya Arutyunyan ◽  
Sergey Dunaev ◽  
Dmitrii D’yakonov
Keyword(s):  
Mechanical Properties ◽  
Structural State ◽  
Strength Properties ◽  
Carbon Steels ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Low Carbon Steels ◽  
Transmission Electron ◽  
Ferrite Fraction ◽  
Hot Rolled

The most promising direction for obtaining a unique combination of difficult-to-combine properties of low-carbon steels is the formation of a dispersed ferrite microstructure and a volumetric system of nanoscale phase precipitates. This study was aimed at establishing the special features of the composition influence on the characteristics of the microstructure, phase precipitates, and mechanical properties of hot-rolled steels of the ferritic class. It was carried out by transmission electron microscopy and testing the mechanical properties of metal using 8 laboratory melts of low-carbon steels microalloyed by V, Nb, Ti, and Mo in various combinations. It was found that block ferrite prevails in the structure of steel cooled after hot rolling at a rate of 10–15 °C/s. Lowering of the microalloying components content leads to a decrease in the block ferrite fraction to 20–35% and the dominance of polygonal ferrite. The presence of nanoscale carbide (carbonitride) precipitates of austenitic and interphase/mixed types was detected in the rolled steels. It was established that the tendencies of changes in the characteristics of the structural state and present phase precipitates correlate well with obtained values of strength properties. The advantages of titanium-based microalloying systems in comparison with vanadium-based are shown.

scholarly journals Mechanical and Microstructural Investigations of the Laser Welding of Different Zinc-Coated Steels

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 91 ◽  
Author(s):  
Eva Zdravecká ◽  
Ján Slota
Keyword(s):  
Mechanical Properties ◽  
Laser Welding ◽  
Heat Affected Zone ◽  
Microstructural Analysis ◽  
Welding Process ◽  
Tensile Tests ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Tailor Welded Blanks ◽  
Carbon Microalloyed

Tailor welded blanks (TWB) represent an anisotropic and non-homogenous material. The knowledge of the mechanical properties and microstructure of the fusion zone and heat-affected zone (HAZ) obtained with laser welding is essential to ensure the reliability of the process. In this paper, laser-welded hot-dip Zn-coated low carbon microalloyed steels with different thickness and mechanical properties were used. The mechanical properties of the laser-welded blanks were determined by tensile tests and formability by Erichsen cupping tests. In addition, the pore formation during the laser welding process was analyzed. The microstructural analysis confirmed the formation of the favorable structure of the weld metal and the heat-affected zone without the presence of martensite. The obtained results showed that it is possible to produce TWBs with suitable mechanical properties by laser welding.

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