Influence of alloying elements on the kinetics of strain-induced martensitic nucleation in low-alloy, multiphase high-strength steels

2006 ◽  
Vol 37 (1) ◽  
pp. 109-124 ◽  
Author(s):  
L. Samek ◽  
E. De Moor ◽  
J. Penning ◽  
B. C. De Cooman
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Alloying Elements ◽  
Kinetics Of ◽  
Martensitic Nucleation

Influence of the Alloying Elements on Phase Transitions of High Strength Steels

2011 ◽  
Vol 337 ◽  
pp. 358-362
Author(s):  
Reimund Neugebauer ◽  
Anja Rautenstrauch ◽  
Enrique Meza Garcia
Keyword(s):  
Phase Transitions ◽  
Steel Sheet ◽  
High Strength Steels ◽  
High Strength ◽  
Alloying Elements ◽  
Quenching Rate ◽  
Steel Alloys ◽  
B Additions ◽  
Alloy Properties ◽  
Cct Diagrams

Continuous Cooling Transformation (CCT) diagrams determined with a dilatometer were used to analyse the influence of the alloying elements on the phase transitions of high strength steel sheet alloys. Mo and Cr additions showed a significant influence on the extension of the bainitic region, whereas C and B additions showed noteworthy improvement on the quenchability of these steel alloys. These alloy properties are desirable requirements to be integrated in hot formed components. In addition to these experimental results, thermodynamic calculations were done with help of the JMatPro software in order to analyse the effect of Mn and C on the resulting mechanical properties as function of the quenching rate.

Effect of Coiling Temperature on Kinetics of Austenite Formation in Cold Rolled Advanced High Strength Steels

2012 ◽  
Vol 706-709 ◽  
pp. 2112-2117 ◽  
Author(s):  
R.R. Mohanty ◽  
O.A. Girina
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Continuous Heating ◽  
Austenite Formation ◽  
Continuous Annealing ◽  
Hard Material ◽  
Low Carbon ◽  
Coiling Temperature ◽  
Hot Rolled ◽  
Kinetics Of

A systematic experimental investigation was conducted using lab processed low carbon 0.08C-2.0Mn-Cr-Mo steel microalloyed with Ti/Nb to evaluate the influence of initial hot-rolled microstructures on the kinetics of austenite formation and decomposition after cold-rolling and subsequent annealing. Coiling temperature as a major hot rolling parameter was used to obtain different types of hot-rolled microstructures. Dilatometer and continuous annealing simulator were employed for austenite formation studies and annealing simulations, respectively. It was found that the coiling temperature affects the processes occurring during heat treatment in continuous annealing lines of full hard material: ferrite recrystallization, austenite formation during continuous heating and austenite decomposition during cooling. A decrease in coiling temperature accelerates the recrystallization of ferrite and nucleation of austenite, which results in formation of refined ferrite-martensite structure. The effect of initial hot rolled structure on final mechanical properties after continuous annealing was also investigated.

Microalloying effects on structure-forming processes during hot plastic deformation

2021 ◽  
pp. 5-16
Author(s):  
S. V. Korotovskaya ◽  
O. V. Sych ◽  
E. I. Khlusova ◽  
N. S. Novoskoltsev
Keyword(s):  
Plastic Deformation ◽  
Deformation Temperature ◽  
Thermal Deformation ◽  
Static Recrystallization ◽  
High Strength Steels ◽  
High Strength ◽  
Homogeneous Structure ◽  
Hot Plastic Deformation ◽  
Austenite Grains ◽  
Kinetics Of

The kinetics of austenite grains' growth upon heating has been investigated, and the processes of dynamic and static recrystallization occurring under different modes of plastic deformation (reduction pattern, deformation temperature) of high-strength steels with various microalloying complexes have been studied. The research made it possible to reveal the thermal deformation conditions for the formation of a finely dispersed homogeneous structure of steel. Technological recommendations have been developed for the production of high-strength steels depending on their microalloying (vanadium, niobium).

Influence of Boron on the Precipitation Kinetics in Advanced Ultra-High Strength Steels

2015 ◽  
Vol 1765 ◽  
pp. 91-96
Author(s):  
G. Altamirano ◽  
I. Mejía ◽  
A. Hernández-Expósito ◽  
J.M. Cabrera
Keyword(s):  
Stress Relaxation ◽  
High Strength Steels ◽  
High Strength ◽  
Relaxation Method ◽  
Low Carbon ◽  
Precipitation Kinetics ◽  
Austenite Recrystallization ◽  
Ultra High Strength Steels ◽  
Relaxation Curves ◽  
Kinetics Of

ABSTRACTIn the present work, the stress relaxation method was employed to determine the influence of B addition on the kinetics of strain-induced precipitation and its interaction with the static austenite recrystallization. For this purpose, the behavior of two low carbon advanced ultra-high strength steels was analyzed during stress relaxation tests at different temperatures and constant pre-strain rate. The precipitation start (Ps) and finish (Pf) times were determined from the relaxation curves and then the corresponding precipitation-time-temperature diagrams were constructed for each steel. Transmission Electron Microscopy was used to determine the chemical nature and evolution of precipitation. In general, the results show that the addition of B retards the austenite recrystallization, tends to accelerate the precipitation kinetics of carbonitrides and leads to a finer and denser distribution of precipitates. These results are discussed in terms of the driving force for the nucleation of precipitation, which in turn is controlled by the degree of supersaturation of microalloying element and as a function of B segregation and B-vacancy complexes to dislocations and grain boundaries.

scholarly journals First-Principles Calculations of Thermal and Electrical Transport Properties of bcc and fcc Dilute Fe–X (X = Al, Co, Cr, Mn, Mo, Nb, Ni, Ti, V, and W) Binary Alloys

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1988
Author(s):  
Yang Lin ◽  
Xiaoyu Chong ◽  
Yingchun Ding ◽  
Yunxuan Zhou ◽  
Mengdi Gan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Transport ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
High Strength Steels ◽  
High Strength ◽  
Alloying Elements ◽  
Total Thermal Conductivity ◽  
Boltzmann Transport ◽  
Ultra High Strength Steels

The adiabatic shear sensitivity of ultra-high-strength steels is closely related to their thermal conductivity. Therefore, it is essential to investigate the effects of alloying elements on the thermal conductivity of ultra-high-strength steel. In this study, the variation in the scattering behavior of electrons with respect to temperature and the mechanism of three-phonon scattering were considered for obtaining the contributions of electrons and phonons, respectively, to the thermal conductivity of alloys while solving the Boltzmann transport equation. By predicting the effect of ten alloying elements on the electronic thermal conductivity (κe), it was found that, at 1200 K, the doping of iron with Ni and Cr endowed iron with κe values of 24.9 and 25.7 W/m K, respectively. In addition, the prediction for the lattice thermal conductivity (κL), which was performed without considering point defect scattering, indicated that elements such as Al, Co, Mn, Mo, V, and Cr demonstrate a positive effect on the lattice thermal conductivity, with values of 3.6, 3.7, 3.0, 3.1, 3.9, and 3.8 W/m K, respectively. The contribution of κL is only 5–15% of the total thermal conductivity (κtotal). The alloying elements exhibited a similar effect on κtotal and κe. Δκi; the change in thermal conductivity with respect to κ0 owing to the alloying element i was evaluated according to the total thermal conductivity. These values were used to understand the effect of the concentration of alloying elements on the thermal conductivity of iron. The Δκi values of Ni, Co, and W were 6.44, 6.80, and 6.06, respectively, indicating a reduction in the thermal conductivity of iron. This paper provides theoretical guidance for the design of ultra-high-strength steels with a high thermal conductivity.

Influence of niobium microalloying on the kinetics of static and dynamic recrystallization during hot rolling of medium-carbon high-strength steels

2020 ◽  
pp. 5-15
Author(s):  
T. V. Knyazyuk ◽  
N. S. Novoskoltsev ◽  
A. A. Zisman ◽  
E. I. Khlusova
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Rolling ◽  
Static Recrystallization ◽  
High Strength Steels ◽  
High Strength ◽  
Medium Carbon Steel ◽  
Medium Carbon ◽  
Niobium Microalloying ◽  
Temperature Strain ◽  
Kinetics Of

The temperature-strain conditions of dynamic and static recrystallization during hot deformation were determined at a rate of 1 sec–1 for medium-carbon steel microalloyed with titanium, boron, and vanadium containing different amounts of niobium. It was found that under hot rolling conditions niobium prevents the completion of dynamic recrystallization, and at temperatures below 970°C it drastically slows down static recrystallization in the pauses between successive reductions.

Segregation and Selective Surface Oxidation at the Intermediate Steps of Recrystallization Annealing

2011 ◽  
Vol 309-310 ◽  
pp. 203-208 ◽  
Author(s):  
Srinivasan Swaminathan ◽  
Michael Rohwerder
Keyword(s):  
High Strength Steels ◽  
Surface Oxidation ◽  
High Strength ◽  
Dew Point ◽  
Alloying Elements ◽  
Recrystallization Annealing ◽  
Annealing Atmosphere ◽  
Surface Evolution ◽  
Fe Oxides ◽  
Binary Model

High strength steels for automotive industry undergo recrystallization annealing in N2-H2 gas atmosphere prior to hot dip galvanizing. Segregation and selective surface oxidation of the alloying elements (Al, Mn, Si, Cr etc.) depending on their extend, can be a serious problem for subsequent galvanizing as the wettability of these oxides with zinc is poor. Moreover, the H2 uptake from the annealing atmosphere majorly depends on the surface evolution during recrystallization annealing. In order to understand the surface phenomena during annealing of multicomponent alloy (i.e. steel), a systematic approach on model alloys is needed. In this work, selective surface oxidation of Mn, Al and the reduction of native Fe oxides in Fe 2 wt. % Mn and Fe 3 wt. % Al binary model alloys have been investigated by interrupting the recrystallization annealing cycle at the desired temperature. The specimens were annealed to various temperatures (200-800 °C) in N2-5%H2 gas atmospheres with a dew point of 30 °C. It has been found that the segregation and selective oxidation of the alloying elements starts at 300 °C whereas the significant reduction of native Fe oxides takes place at 400 °C. Further increase of temperature, increases the surface coverage by forming the oxide islands.

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