Tnr Dependent Hot Rolling Microstructure and Texture Development in C-Mn Dual Phase and HSLA Steels

2019 ◽  
Vol 391 ◽  
pp. 120-127
Author(s):  
J. Prakash Gautam ◽  
A. Miroux ◽  
Jaap Moerman ◽  
Leo Kestens
Keyword(s):  
Hot Rolling ◽  
High Strength ◽  
Transformation Products ◽  
Dual Phase ◽  
X Ray Diffraction ◽  
Dual Phase Steels ◽  
Hsla Steels ◽  
Final Microstructure ◽  
Evolution Of Microstructure ◽  
Parent Austenite

No recrystallization of austenite, Tnr, has an important influence on the transformed phase fractions and the final crystallographic texture after hot deformation. This paper investigates the evolution of microstructure and texture components during hot-rolling in two austenitic region based on Tnr along with three different cooling trajectory and coiling in dual-phase steels and high strength low alloys steel. The recrystallization of the austenite, the austenite deformation followed by the austenite-to-ferrite transformation influence the final microstructure and texture in dual phase steels, have been examined by means of optical microscopy, X-ray diffraction (XRD) measurements. Recrystallized and deformed austenite have clearly different texture components and, due to the specific lattice correspondence relations between the parent austenite phase and its transformation products, the resulting ferrite textures are different as well.

scholarly journals Study of the Microstructure and Strain Induced Precipitation during Thermomechanical Processing of Low Carbon Microalloyed Steels

2012 ◽  
Vol 706-709 ◽  
pp. 2118-2123
Author(s):  
Manuel Gómez ◽  
Pilar Valles ◽  
Sebastián F. Medina
Keyword(s):  
Hot Rolling ◽  
Thermomechanical Processing ◽  
High Strength ◽  
Transformation Products ◽  
Carbon Steels ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Mean Flow ◽  
Wide Range ◽  
Final Microstructure

A series of anisothermal multipass hot torsion tests were carried out to simulate hot rolling on three high-strength low-carbon steels with different amounts of Mn, Mo, Nb and Ti and designed for pipeline construction. Mean Flow Stress was graphically represented against the inverse of temperature to characterize the evolution of austenite microstructure during rolling. The effect of austenite strengthening obtained at the end of thermomechanical processing on the final microstructure obtained after cooling was studied. 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. This combined effect gives rise to a wide range of final microstructures and mechanical properties depending on the composition, processing schedule and cooling rates applied. On the other hand, the precipitation state obtained at diverse temperatures during and at the end of hot rolling schedule was evaluated by means of transmission electron microscopy (TEM) in two microalloyed steels. It was found that two families of precipitates with different morphology, composition and mean size can coexist in microalloyed steels.

The limit drawing ratio and formability prediction of advanced high strength dual-phase steels

2011 ◽  
Vol 32 (6) ◽  
pp. 3320-3327 ◽  
Author(s):  
Wang Wu-rong ◽  
He Chang-wei ◽  
Zhao Zhong-hua ◽  
Wei Xi-cheng
Keyword(s):  
High Strength ◽  
Drawing Ratio ◽  
Dual Phase ◽  
Limit Drawing Ratio ◽  
Dual Phase Steels ◽  
Formability Prediction

scholarly journals A Unified Model for Plasticity in Ferritic, Martensitic and Dual-Phase Steels

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 764
Author(s):  
Shuntaro Matsuyama ◽  
Enrique I. Galindo-Nava
Keyword(s):  
Grain Size ◽  
Dislocation Density ◽  
Carbon Content ◽  
Grain Boundaries ◽  
Uniform Elongation ◽  
High Strength Steels ◽  
High Strength ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Dislocation Generation

Unified equations for the relationships among dislocation density, carbon content and grain size in ferritic, martensitic and dual-phase steels are presented. Advanced high-strength steels have been developed to meet targets of improved strength and formability in the automotive industry, where combined properties are achieved by tailoring complex microstructures. Specifically, in dual-phase (DP) steels, martensite with high strength and poor ductility reinforces steel, whereas ferrite with high ductility and low strength maintains steel’s formability. To further optimise DP steel’s performance, detailed understanding is required of how carbon content and initial microstructure affect deformation and damage in multi-phase alloys. Therefore, we derive modified versions of the Kocks–Mecking model describing the evolution of the dislocation density. The coefficient controlling dislocation generation is obtained by estimating the strain increments produced by dislocations pinning at other dislocations, solute atoms and grain boundaries; such increments are obtained by comparing the energy required to form dislocation dipoles, Cottrell atmospheres and pile-ups at grain boundaries, respectively, against the energy required for a dislocation to form and glide. Further analysis is made on how thermal activation affects the efficiency of different obstacles to pin dislocations to obtain the dislocation recovery rate. The results are validated against ferritic, martensitic and dual-phase steels showing good accuracy. The outputs are then employed to suggest optimal carbon and grain size combinations in ferrite and martensite to achieve highest uniform elongation in single- and dual-phase steels. The models are also combined with finite-element simulations to understand the effect of microstructure and composition on plastic localisation at the ferrite/martensite interface to design microstructures in dual-phase steels for improved ductility.

An integrated hot rolling and microstructure model for dual-phase steels

2014 ◽  
Vol 22 (4) ◽  
pp. 045005 ◽  
Author(s):  
D Bombac ◽  
M J Peet ◽  
S Zenitani ◽  
S Kimura ◽  
T Kurimura ◽  
...  
Keyword(s):  
Hot Rolling ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Microstructure Model

Development of Laminar Flow Cooling of Ultra-High Strength Ferrite-Bainite Dual Phase Steel

2012 ◽  
Vol 184-185 ◽  
pp. 940-943
Author(s):  
Wei Lv ◽  
Di Wu ◽  
Zhuang Li
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Laminar Flow ◽  
Hot Rolling ◽  
Retained Austenite ◽  
High Strength ◽  
Total Elongation ◽  
Granular Bainite ◽  
Dual Phase ◽  
Dp Steel

In the present paper, controlled cooling in different ways was performed using a laboratory hot rolling mill in ultra-high strength hot rolled ferrite-bainite dual phase (DP) steel. The results have shown that the final microstructures of DP steel comprise ferrite, bainite and a small amount of retained austenite and martensite. DP steel has a tensile strength ranging from 1010 to 1130MPa and yet retains considerable total elongation in the range of 14–17%. The addition of Mn and Nb to DP steel leads to the maximum ultimate tensile strength, yield strength and the product of ultimate tensile strength and total elongation due to the formation of retained austenite and granular bainite structure. Laminar flow cooling after hot rolling results in a significant increase in the quantity of ferrite and bainite due to the suppression of pearlite transformation, and as a result, the present steel possesses high strengths and good toughness.

A novel approach to producing architectured ultra-high strength dual phase steels

2021 ◽  
pp. 142582
Author(s):  
Hamid Azizi ◽  
Javad Samei ◽  
Hatem S. Zurob ◽  
David S. Wilkinson ◽  
David Embury
Keyword(s):  
High Strength ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Novel Approach
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