Austenite formation and mechanical properties of a cold rolled ferrite-martensite structure during intercritical annealing

: The effect that the microstructure exerts on the TRIP phenomenon and on the mechanical properties in a multiphase steel was studied. Samples of an initially cold-rolled ferrite-pearlite steel underwent different intercritical annealing treatments at 750 °C until an equal fractions of austenite/ferrite was reached; the intercritical treatment was followed by isothermal bainitic treatments before cooling the samples to room temperature. Samples in the first treatment were heated  directly to the intercritical temperature, whereas other samples were heated to either 900 or 1100 °C to obtain a fully homogenized, single phase austenitic microstructure prior to the conducting the intercritical treatment. The high temperature homogenization of austenite resulted in the decrease in its stability, so a considerable austenite fraction transformed into martensite by cooling to room temperature after the bainitic heat treatment. Most of the retained austenite transformed during the tensile tests, and as a consequence, the previously homogenized steels showed the highest UTS. In turn, the steel with a ferritic-pearlitic initial microstructure, exhibited higher ductility than the other steels and texture components that favor forming processes.     

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Effects of Heat Treatment on Morphology, Texture, and Mechanical Properties of a MnSiAl Multiphase Steel with TRIP Behavior

Metals ◽

10.3390/met8121021 ◽

2018 ◽

Vol 8 (12) ◽

pp. 1021 ◽

Cited By ~ 2

Author(s):

Alvaro Salinas ◽

Alfredo Artigas ◽

Juan Perez-Ipiña ◽

Felipe Castro-Cerda ◽

Nelson Garza-Montes-de-Oca ◽

...

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Room Temperature ◽

Single Phase ◽

Intercritical Annealing ◽

Tensile Tests ◽

Transformation Induced Plasticity ◽

Temperature Homogenization ◽

Cold Rolled ◽

Multiphase Steel

The effect that the microstructure exerts on the Transformation-Induced Plasticity (TRIP) phenomenon and on the mechanical properties in a multiphase steel was studied. Samples of an initially cold-rolled ferrite–pearlite steel underwent different intercritical annealing treatments at 750 °C until equal fractions of austenite/ferrite were reached; the intercritical treatment was followed by isothermal bainitic treatments before cooling the samples to room temperature. Samples in the first treatment were heated directly to the intercritical temperature, whereas other samples were heated to either 900 °C or 1100 °C to obtain a fully homogenized, single-phase austenitic microstructure before performing the intercritical treatment. The high-temperature homogenization of austenite resulted in a decrease in its stability, so a considerable austenite fraction transformed into martensite by cooling to room temperature after the bainitic heat treatment. Most of the retained austenite transformed during the tensile tests, and, consequently, the previously homogenized steels showed the highest Ultimate Tensile Strength (UTS). In turn, the steel with a ferritic–pearlitic initial microstructure exhibited higher ductility than the other steels and texture components that favor forming processes.

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Microstructural Evolution and Recrystallization Kinetics of a Cold-Rolled, Ferrite-Martensite Structure During Intercritical Annealing

Metallurgical and Materials Transactions A ◽

10.1007/s11661-016-3528-1 ◽

2016 ◽

Vol 47 (7) ◽

pp. 3271-3276 ◽

Cited By ~ 7

Author(s):

S. A. Etesami ◽

M. H. Enayati

Keyword(s):

Microstructural Evolution ◽

Intercritical Annealing ◽

Recrystallization Kinetics ◽

Cold Rolled ◽

Kinetics Of ◽

Martensite Structure

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Recrystallization, grain growth and austenite formation in cold rolled steels during intercritical annealing

Journal of Materials Research and Technology ◽

10.1016/j.jmrt.2020.08.015 ◽

2020 ◽

Vol 9 (5) ◽

pp. 11263-11277 ◽

Cited By ~ 1

Author(s):

Okan Poyraz ◽

Bilgehan Ögel

Keyword(s):

Grain Growth ◽

Intercritical Annealing ◽

Austenite Formation ◽

Cold Rolled

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Grain Refinement of a Cold Rolled TRIP Assisted Steel after Ultra Short Annealing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.715-716.661 ◽

2012 ◽

Vol 715-716 ◽

pp. 661-666 ◽

Cited By ~ 12

Author(s):

Roumen H. Petrov ◽

Jurij J. Sidor ◽

Wlodzimierz Kaluba ◽

Leo Kestens

Keyword(s):

Grain Size ◽

Grain Refinement ◽

Steel Sheet ◽

Intercritical Annealing ◽

Austenite Formation ◽

Rolled Steel ◽

Structural Refinement ◽

Cold Rolled ◽

Short Annealing ◽

Ferrite Grain Size

Recrystallization and austenite formation in a TRIP-assisted steel during conventional and ultra fast reheating for intercritical annealing are studied with the purpose to clarify the possibility for grain refinement. Partially recrystallized (or transformed) samples were prepared by reheating and water quenching to temperatures between 650 and 1050°C at reheating rates of 10, 50, and 3000 °C/s, respectively, without isothermal soaking from 95% cold rolled steel sheet with ferrite-pearlite microstructure. By monitoring the hardness and microstructure, it was shown that the increase of the reheating rate from 10 to 3000°C/s causes grain refinement from 5µm to 1µm in diameter and the final ferrite grain size depends significantly on both reheating temperature and reheating rate. It was observed that after an extreme reheating rate of 3000°C/s the α-γ phase transformation starts before the completion of the recrystallization. This opens up possibilities for further structural refinement and alternative texture control.

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