scholarly journals Thermomechanical processing route to achieve ultrafine grains in low carbon microalloyed steels

2016 ◽  
Vol 119 ◽  
pp. 43-54 ◽  
Author(s):  
P. Gong ◽  
E.J. Palmiere ◽  
W.M. Rainforth
Keyword(s):  
Thermomechanical Processing ◽  
Microalloyed Steels ◽  
Processing Route ◽  
Low Carbon ◽  
Ultrafine Grains ◽  
Carbon Microalloyed

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.

scholarly journals Effect of Mo, Nb and V on Hot Deformation Behaviour, Microstructure and Hardness of Microalloyed Steels

2018 ◽  
Vol 941 ◽  
pp. 3-8
Author(s):  
Navjeet Singh ◽  
Andrii G. Kostryzhev ◽  
Chris R. Killmore ◽  
Elena V. Pereloma
Keyword(s):  
Thermomechanical Processing ◽  
Deformation Behaviour ◽  
Solute Drag ◽  
Granular Bainite ◽  
Recrystallization Temperature ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Iron Carbides ◽  
Bainite Microstructure ◽  
Carbon Microalloyed

Three novel low carbon microalloyed steels with various additions of Mo, Nb and V were investigated after thermomechanical processing simulations designed to obtain ferrite-bainite microstructure. With the increase in microalloying element additions from the High V- to NbV- to MoNbV-microalloyed steel, the high temperature flow stresses increased. The MoNbV and NbV steels have shown a slightly higher non-recrystallization temperature (1000 °C) than the High V steel (975 °C) due to the solute drag from Nb and Mo atoms and austenite precipitation of Nb-rich particles. The ambient temperature microstructures of all steels consisted predominantly of polygonal ferrite with a small amount of granular bainite. Precipitation of Nb-and Mo-containing carbonitrides (>20 nm size) was observed in the MoNbV and NbV steels, whereas only coarser (~40 nm) iron carbides were present in the High V steel. Finer grain size and larger granular bainite fraction resulted in a higher hardness of MoNbV steel (293 HV) compared to the NbV (265 HV) and High V (285 HV) steels.

Mechanism of Microstructural Banding in Hot Rolled Microalloyed Steels

2005 ◽  
Vol 500-501 ◽  
pp. 171-178 ◽  
Author(s):  
S. Cai ◽  
J.D. Boyd
Keyword(s):  
Grain Growth ◽  
Thermomechanical Processing ◽  
Boundary Migration ◽  
Pilot Scale ◽  
Abnormal Grain Growth ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Plate Rolling ◽  
Austenite Grains ◽  
Carbon Microalloyed

Pilot-scale plate rolling experiments and laboratory thermomechanical processing experiments were carried out to understand the mechanism of microstructural banding in low-carbon microalloyed steels. The microstructural banding originates with large elongated austenite grains, which are present at the roughing stage of rolling. The large austenite grains develop when conditions favour abnormal grain growth during reheat and/or strain induced grain boundary migration (SIBM) in the first few rolling passes. Microstructural banding is eliminated by designing TMP schedules to avoid abnormal grain growth and SIBM.

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.

Evidence of Strain-Induced Precipitation on a Nb- and N-Bearing Austenitic Stainless Steel Biomaterial

2005 ◽  
Vol 500-501 ◽  
pp. 179-186 ◽  
Author(s):  
E.J. Giordani ◽  
Alberto Moreira Jorge ◽  
O. Balancin
Keyword(s):  
Grain Growth ◽  
Thermomechanical Processing ◽  
Boundary Migration ◽  
Pilot Scale ◽  
Abnormal Grain Growth ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Plate Rolling ◽  
Austenite Grains ◽  
Carbon Microalloyed

Pilot-scale plate rolling experiments and laboratory thermomechanical processing experiments were carried out to understand the mechanism of microstructural banding in low-carbon microalloyed steels. The microstructural banding originates with large elongated austenite grains, which are present at the roughing stage of rolling. The large austenite grains develop when conditions favour abnormal grain growth during reheat and/or strain induced grain boundary migration (SIBM) in the first few rolling passes. Microstructural banding is eliminated by designing TMP schedules to avoid abnormal grain growth and SIBM.

Effect of Mo Concentration on Dynamic Recrystallization Behavior of Low Carbon Microalloyed Steels

2013 ◽  
Vol 84 (12) ◽  
pp. 1191-1195 ◽  
Author(s):  
Thomas Schambron ◽  
Liang Chen ◽  
Taliah Gooch ◽  
Ali Dehghan-Manshadi ◽  
Elena V. Pereloma
Keyword(s):  
Dynamic Recrystallization ◽  
Microalloyed Steels ◽  
Recrystallization Behavior ◽  
Low Carbon ◽  
Dynamic Recrystallization Behavior ◽  
Carbon Microalloyed

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.

Isothermal transformation of low-carbon microalloyed steels

2005 ◽  
Vol 54 (4-5) ◽  
pp. 417-422 ◽  
Author(s):  
Furen Xiao ◽  
Bo Liao ◽  
Yiyin Shan ◽  
Ke Yang
Keyword(s):  
Isothermal Transformation ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Carbon Microalloyed

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.

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