Ferrite Formation Above the Ae3 in a Medium-Carbon Steel

2011 ◽  
Vol 172-174 ◽  
pp. 372-377 ◽  
Author(s):  
John J. Jonas ◽  
Vladimir V. Basabe
Keyword(s):  
Critical Strain ◽  
Volume Fraction ◽  
Isothermal Holding ◽  
Medium Carbon Steel ◽  
Medium Carbon ◽  
Ferrite Formation ◽  
Grain Sizes ◽  
Dynamic Transformation ◽  
Gas Atmosphere ◽  
Experimental Parameters

A 0.45% C steel was deformed in torsion over the temperature range 762-872°C in a 5%H2-Argas atmosphere. Strains of 0.25-3.0 were applied at a strain rate of ε.= 4 s-1. The experimental parameters were varied in order to study the effects of strain and temperature on the formation of ferrite by dynamic transformation (DT) at temperatures above the Ae3. The critical strain for ferrite formation by DT was about 0.2 and its volume fraction increased with strain. The average ferrite grain sizes were about 1 to 2 µm and were fairly independent of temperature. It was observed that the deformation-induced ferrite remained fairly stable during 800 s of isothermal holding. In general, the experiments showed that DT takes place at temperatures above the Ae3and that the reversestatictransformation is much slower than the forwarddynamictransformation.

Formation of Deformation-Induced Divorced Eutectoid Pearlite above the Ae1

2011 ◽  
Vol 409 ◽  
pp. 829-834 ◽  
Author(s):  
Vladimir V. Basabe ◽  
John J. Jonas ◽  
Chiradeep Ghosh
Keyword(s):  
Carbon Steel ◽  
Strain Rate ◽  
Isothermal Holding ◽  
Plain Carbon Steel ◽  
Dynamic Transformation ◽  
Gas Atmosphere ◽  
Experimental Parameters ◽  
Intercritical Region ◽  
Ar Gas ◽  
Parent Austenite

A 0.21% C plain carbon steel was deformed in torsion to strains of ε = 0.15-3.0 at a strain rate of ε ̇= 4.5 s-1 over the temperature range 722-822°C in a 5%H2-Ar gas atmosphere. The experimental parameters were varied in order to study the formation of ferrite and pearlite by dynamic transformation (DT) in the intercritical region. This transformation was observed right up to the highest experimental temperature (822°C). The pearlite formed by DT contained cementite spheroids whose size distribution evolved during isothermal holding after deformation. In the first stage, corresponding to the first 800 s of holding, spheroid coarsening took place. When the holding time exceeded 800 s, the spheroids dissolved and the pearlite reverted into the original parent austenite. The results indicate that pearlite can form by DT at temperatures well above the Ae1 and that the reverse static transformation is much slower than the forward dynamic transformation.

scholarly journals On the decomposition of austenite in a high-silicon medium-carbon steel during quenching and isothermal holding above and below the Ms temperature

2020 ◽  
Vol 162 ◽  
pp. 110224 ◽  
Author(s):  
S. Pashangeh ◽  
M.C. Somani ◽  
S.S. Ghasemi Banadkouki ◽  
H.R. Karimi Zarchi ◽  
P. Kaikkonen ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Isothermal Holding ◽  
Medium Carbon Steel ◽  
Medium Carbon ◽  
High Silicon

scholarly journals Acicular ferrite formation in a medium carbon steel with a two stage continuous cooling

1999 ◽  
Vol 41 (3) ◽  
pp. 229-235 ◽  
Author(s):  
I Madariaga ◽  
I Gutiérrez ◽  
C Garcı́a-de Andrés ◽  
C Capdevila
Keyword(s):  
Carbon Steel ◽  
Acicular Ferrite ◽  
Medium Carbon Steel ◽  
Two Stage ◽  
Medium Carbon ◽  
Ferrite Formation ◽  
Continuous Cooling

Effect of Number of Roughing Passes on the Dynamic Transformation of Austenite during Simulated Plate Rolling

2018 ◽  
Vol 941 ◽  
pp. 717-722
Author(s):  
Samuel F. Rodrigues ◽  
Fulvio Siciliano ◽  
Clodualdo Aranas Jr. ◽  
Gedeon S. Reis ◽  
Brian J. Allen ◽  
...  
Keyword(s):  
Grain Size ◽  
Volume Fraction ◽  
Austenite Phase ◽  
Mean Flow ◽  
Grain Sizes ◽  
Dynamic Transformation ◽  
Plate Rolling ◽  
Forward Transformation ◽  
The Mean ◽  
Rough Rolling

When austenite is deformed within the austenite phase field, it partially transforms dynamically into ferrite. Here, plate rolling simulations were carried out on an X70 steel using rough rolling passes of 0.4 strain each. The influence of the number of roughing passes on the grain size and volume fraction of induced ferrite was determined. Up to three roughing passes applied at 1100 °C followed by 5 finishing passes at 900 °C were employed. The sample microstructures were analysed by means of metallographic techniques. Both the critical strain to the onset of dynamic transformation as well as the grain size decreased with pass number during the roughing simulations. For the finishing passes, the mean flow stresses (MFS`s) applicable to each schedule decreased when a higher number of roughing passes was applied. The volume fraction of dynamically formed ferrite retained after simulated rolling increased with the roughing pass number. This is ascribed to the increased amount of ferrite retransformed into austenite and the finer grain sizes produced during roughing. The forward transformation is considered to occur displacively while the retransformation into austenite during holding takes place by a diffusional mechanism. This indicates that both dynamic transformation (DT) and dynamic recrystallization were taking place during straining.

Effect of Different Strain on Microstructure Evolution of Medium Carbon Steel

2013 ◽  
Vol 652-654 ◽  
pp. 923-928 ◽  
Author(s):  
Peng Tian ◽  
Zhi Yong Zhong ◽  
Wei Jun Hui ◽  
Rui Guo Bai ◽  
Xing Li Zhang
Keyword(s):  
Carbon Steel ◽  
Microstructure Evolution ◽  
Simulation Experiment ◽  
Volume Fraction ◽  
True Strain ◽  
Medium Carbon Steel ◽  
Controlled Cooling ◽  
Medium Carbon ◽  
The Right ◽  
Equilibrium Content

Uniaxial hot compression simulation experiment at 700°C with different true strain was carried out to study the microstructure evolution of medium carbon steel, the predominant mechanism on the cementite softening has been explored, the experimental results show that the volume fraction of deformation induced ferrite (DIF) increased with increasing true strain and even exceeds the equilibrium content. With the increase of DIF, more and more carbon atoms congregated in the boundaries such as the interface of DIF and the interphase of DIF/deformation austenite. Carbon congregation provides the right carbon content and the optimized microstructure for divorced decomposition during the process of controlled cooling. Therefore spherical or rod-like cementite and degenerated pearlite can be obtained.

Austenite Stabilization by Quenching and Partitioning in a Low-Alloy Medium Carbon Steel

2012 ◽  
Vol 706-709 ◽  
pp. 2234-2239
Author(s):  
E. Paravicini Bagliani ◽  
E. Anelli ◽  
Marco Boniardi
Keyword(s):  
Retained Austenite ◽  
Room Temperature ◽  
Isothermal Holding ◽  
High Strength Steels ◽  
High Strength ◽  
Medium Carbon Steel ◽  
Medium Carbon ◽  
Quenching And Partitioning ◽  
Untransformed Austenite

Innovative treatments like quenching and partitioning (Q&P) have been recently proposed to improve the combination of strength and ductility of high strength steels by stabilization of significant fractions of retained austenite in a microstructure of tempered martensite. The decomposition of austenite into bainite and carbides precipitation are the two main competitive processes that reduce the content of retained austenite achievable at room temperature. A medium carbon low-silicon steel (0.46% C and 0.25% Si) has been studied to identify in which limits the austenite can be enriched in C and stabilized by Q&P, although a silicon content well below 1.5%, commonly used to retard cementite precipitation, is adopted; indeed, high Si contents are detrimental to the surface quality of the product due to the formation of adherent scale in high temperature manufacturing cycles. The heat treatments have been carried out with a quenching dilatometer, investigating the carbon partitioning process mainly below Ms, where cementite precipitation is not activated. The dilatometric curves show the progressive enrichment of carbon in the untransformed austenite and the occurrence of austenite phase transformation during the isothermal holding below Ms. A range of temperatures and times has been found where a content of about 10% of retained austenite can be stabilized at room temperature, a percentage much lower than the theoretical maximum achievable with the carbon content of this steel.

The Effect of Controlled Rolling and Cooling on the Microstructure Evolution of Boron Microalloyed Medium-Carbon Steel

2010 ◽  
Vol 146-147 ◽  
pp. 1305-1309
Author(s):  
Wu Hua Yuan ◽  
Qiang Fu ◽  
Heng Zhou
Keyword(s):  
Carbon Steel ◽  
Grain Boundaries ◽  
Microstructure Evolution ◽  
Volume Fraction ◽  
Controlled Rolling ◽  
Medium Carbon Steel ◽  
Rolling Temperature ◽  
Compression Tests ◽  
Medium Carbon ◽  
Average Grain Size

The processes of controlled rolling and cooling were simulated using hot compression tests on a Gleeble 1500 simulator with boron microalloyed medium-carbon steel. Effects of finish rolling temperature ranging from 760oC to 840oC and loop-laying temperature ranging from 660oC to 700oC on the microstructure evolution were studied. Experimental observations show that the average grain size of ferrite decreases while the volume fractions of ferrite and spheroidized pearlite increase when lowering rolling temperature. The maximum volume fraction of ferrite (62%) reached in our tests was obtained in the specimen whose rolling temperature and loop-laying temperature was 760oC and 700oC respectively. Excessive precipitation of the ferrite resulted in the carbon enrichment on some grain boundaries. Boron addition is effective to improve hot plastic deformation ability by removing nitrogen from AlN to form coarse BN particles on the grain boundaries.

Induced ferrite formation above the Ae3 during plate rolling simulation of a X70 steel

MRS Advances ◽  
2019 ◽  
Vol 4 (57-58) ◽  
pp. 3077-3085
Author(s):  
Samuel F. Rodrigues ◽  
Thiago B. Carneiro ◽  
Clodualdo Aranas ◽  
Eden S. Silva ◽  
Fulvio Siciliano ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Accelerated Cooling ◽  
Strain Accumulation ◽  
Mean Flow ◽  
Ferrite Formation ◽  
Dynamic Transformation ◽  
Cooling Conditions ◽  
Plate Rolling ◽  
Stable Austenite ◽  
The Mean

ABSTRACTPartial amount of austenite can be dynamically transformed into ferrite above the Ae3 temperature when it is being deformed. This happens by a displacive mechanism. On removal of the load, it retransforms back into the stable austenite by diffusional processes. Plate rolling simulation under continuous cooling conditions was carried out on a high Nb X70 steel. Pass strains of 0.2 together with interpass times of 10, 20 and 30 s were employed. The initial and final temperatures for the finishing simulation were 920 and 830 °C, respectively. The mean flow stresses (MFS`s) behaviour indicates that dynamic transformation (DT) and recrystallization (DRX) were taking place during straining. It is shown that ferrite is formed during the roughing passes and increases its volume fraction throughout the finishing rolling steps. The ferrite formation is favoured by strain accumulation, shorter time between passes and also when the temperature reaches the Ae3 line. The results obtained here can be used to design improved models for transformation on accelerated cooling.

INFLUENCE THE QUENCHING AND TEMPERING ON THE MICROSTRUCTURE, MECHANICAL PROPERTIES AND SURFACE ROUGHNESS, OF MEDIUM CARBON STEEL

2018 ◽  
Vol 18 (1) ◽  
pp. 125-135
Author(s):  
Sattar H A Alfatlawi
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Surface Roughness ◽  
Carbon Steel ◽  
Cold Water ◽  
Medium Carbon Steel ◽  
Medium Carbon ◽  
Heating And Cooling ◽  
Treatment Processes ◽  
Quenching And Tempering

One of ways to improve properties of materials without changing the product shape toobtain the desired engineering applications is heating and cooling under effect of controlledsequence of heat treatment. The main aim of this study was to investigate the effect ofheating and cooling on the surface roughness, microstructure and some selected propertiessuch as the hardness and impact strength of Medium Carbon Steel which treated at differenttypes of heat treatment processes. Heat treatment achieved in this work was respectively,heating, quenching and tempering. The specimens were heated to 850°C and left for 45minutes inside the furnace as a holding time at that temperature, then quenching process wasperformed in four types of quenching media (still air, cold water (2°C), oil and polymersolution), respectively. Thereafter, the samples were tempered at 200°C, 400°C, and 600°Cwith one hour as a soaking time for each temperature, then were all cooled by still air. Whenthe heat treatment process was completed, the surface roughness, hardness, impact strengthand microstructure tests were performed. The results showed a change and clearimprovement of surface roughness, mechanical properties and microstructure afterquenching was achieved, as well as the change that took place due to the increasingtoughness and ductility by reducing of brittleness of samples.

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