Study of the Plastic Deformation in Nanocrystalline and Ultrafine Iron and Carbon Steels

2008 ◽  
Vol 584-586 ◽  
pp. 617-622 ◽  
Author(s):  
Josep Antonio Benito ◽  
Robert Tejedor ◽  
Rodriguez Rodríguez-Baracaldo ◽  
Jose María Cabrera ◽  
Jose Manuel Prado
Keyword(s):  
Grain Size ◽  
Low Carbon Steel ◽  
High Strength ◽  
Carbon Steels ◽  
Low Carbon ◽  
Compression Tests ◽  
Consolidation Process ◽  
Heat Treated ◽  
Average Grain Size ◽  
Grain Size Distributions

Samples of nanostructured and ultrafine grained steels with carbon content ranging from 0.05 to 0.55%wt. have been obtained by a warm consolidation process from mechanically milled powders and subsequent heat treatments. In general, homogeneous grain size distributions were obtained except for the low-carbon steel in which a bimodal grain size distribution was observed when it was heat treated at high temperatures. The stress-strain response has been studied by means of compression tests. Nanostructured materials showed high strength but poor results in terms of ductility. In the low-ultrafine range (mean grain size between 100-500 nm) the three materials showed an increase in the ductility with strain softening. Finally, when the average grain size was close to 1 µm samples showed larger ductility and strain hardening.

scholarly journals Effect of Carbon Partitioning, Carbide Precipitation, and Grain Size on Brittle Fracture of Ultra-High-Strength, Low-Carbon Steel after Welding by a Quenching and Partitioning Process

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 747 ◽  
Author(s):  
Farnoosh Forouzan ◽  
M. Guitar ◽  
Esa Vuorinen ◽  
Frank Mücklich
Keyword(s):  
Grain Size ◽  
Carbon Steel ◽  
Weld Zone ◽  
Low Carbon Steel ◽  
High Strength ◽  
Precipitate Size ◽  
Low Carbon ◽  
Quenching And Partitioning ◽  
High Level ◽  
The Impact

To improve the weld zone properties of Advanced High Strength Steel (AHSS), quenching and partitioning (Q&P) has been used immediately after laser welding of a low-carbon steel. However, the mechanical properties can be affected for several reasons: (i) The carbon content and amount of retained austenite, bainite, and fresh martensite; (ii) Precipitate size and distribution; (iii) Grain size. In this work, carbon movements during the partitioning stage and prediction of Ti (C, N), and MoC precipitation at different partitioning temperatures have been simulated by using Thermocalc, Dictra, and TC-PRISMA. Verification and comparison of the experimental results were performed by optical microscopy, X-ray diffraction (XRD), Scanning Electron Microscop (SEM), and Scanning Transmission Electron Microscopy (STEM), and Energy Dispersive Spectroscopy (EDS) and Electron Backscatter Scanning Diffraction (EBSD) analysis were used to investigate the effect of martensitic/bainitic packet size. Results show that the increase in the number density of small precipitates in the sample partitioned at 640 °C compensates for the increase in crystallographic packets size. The strength and ductility values are kept at a high level, but the impact toughness will decrease considerably.

Surface Nanocrystallization of Low Carbon Steel Induced by Circulation Rolling Plastic Deformation

2005 ◽  
Vol 475-479 ◽  
pp. 133-136 ◽  
Author(s):  
Xin Min Fan ◽  
Bosen Zhou ◽  
Lin Zhu ◽  
Heng Zhi Wang ◽  
Jie Wen Huang
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Surface Layer ◽  
Carbon Steel ◽  
Severe Plastic Deformation ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Surface Nanocrystallization ◽  
Average Grain Size ◽  
The Matrix

In this paper, the circulation rolling plastic deformation(CRPD) surface nanocrystallization technology is proposed based on the idea that the severe plastic deformation can induce grain refinement. The equipment of CRPD is designed and manufactured. A nanocrystallization surface layer was successfully obtained in a column sample of low carbon steel. The average grain size in the top surface layer is about 18 nm, and gradually increases with the distance from the surface. The hardness increases gradually from about 200HV0.1 in the matrix to about 600HV0.1 in the surface layer.

Tempering of Direct Quenched Low-Alloy Ultra-High-Strength Steel, Part I – Microstructure

2014 ◽  
Vol 922 ◽  
pp. 316-321 ◽  
Author(s):  
Antti J. Kaijalainen ◽  
Sakari Pallaspuro ◽  
David A. Porter
Keyword(s):  
Grain Size ◽  
Low Carbon Steel ◽  
High Strength ◽  
Steel Part ◽  
Grain Structure ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Direct Quenching ◽  
Austenite Grain ◽  
Effective Grain Size

The direct quenching of low-carbon steel has been shown to be an effective way of producing ultra-high-strength, tough structural steels in the as-quenched state without tempering. However, in the present study, the influence of tempering at 500 °C has been studied in order to evaluate the possibilities of widening the range of strengths that can be produced from a single base composition. The chosen composition was 0.1C-0.2Si-1.1Mn-0.15Mo-0.03Ti-0.002B. In order to compare direct quenching with conventional quenching, two pre-quench austenite states were studied: a thermomechanically rolled, non-recrystallized, pancaked austenite grain structure and a recrystallized, equiaxed grain structure. Quenched and quenched-and-tempered microstructures were studied using FESEM and FESEM-EBSD. The as-quenched microstructures of the reheated and quenched and direct quenched specimens were fully martensitic and martensitic-bainitic, respectively. In both cases, tempering made the needle-shaped auto-tempered carbides of the as-quenched materials more spherical. In the case of the direct quenched (DQ) material, tempering led to a notable increase in the size of the grain boundary carbides. Prior austenite grain size and effective grain size after quenching were larger in the case of reheated and quenched material (RQ). Tempering had no effect on effective grain size. The crystallographic texture of the DQ material showed strong {112}<131> and {554}<225> components. The RQ material also contained the same components, but it also contained an intense {110}<110> and {011}<100> components. The effects of these microstructural changes on tensile, impact toughness and fracture toughness are described in part II.

Effect of Hot Band Grain Size on the Anisotropy of Warm Rolled Low Carbon Steels

2005 ◽  
Vol 500-501 ◽  
pp. 787-794
Author(s):  
M. Sánchez-Araiza ◽  
Stéphane Godet ◽  
Pascal J. Jacques ◽  
John J. Jonas
Keyword(s):  
Grain Size ◽  
Shear Banding ◽  
Shear Bands ◽  
Low Carbon Steel ◽  
Carbon Steels ◽  
Low Carbon ◽  
Flow Localization ◽  
Normal Anisotropy ◽  
Annealing Texture ◽  
Hot Band

In warm rolled steels, the intensity of the <111>//ND annealing texture, which favours formability, has been related to the formation of shear bands during rolling. Coarse hot band grain sizes (HBGS’s) facilitate flow localization, the mechanism associated with the formation of shear bands.In this work, the effect of grain size after hot rolling was studied in a low carbon steel containing small additions of Cr and Mn. The formation of shear bands and their subsequent influence on the normal anisotropy rm and planar anisotropy Dr in the annealed steels were of particular interest. Two HBGS’s (18 and 30mm) were employed and the specimens were warm rolled to reductions of 65 and 80% at various temperatures between 640 and 700°C. The results show that the frequency of shear banding is slightly lower for the smaller grain size. The normal anisotropy was not affected by the HBGS; by contrast, much lower Dr values were associated with the finer grained steel.

Effects of Thermo-Mechanical Process on the Microstructure and Mechanical Properties of Low Carbon HSLA Steels

2006 ◽  
Vol 15-17 ◽  
pp. 786-791 ◽  
Author(s):  
J.S. Kang ◽  
Y. Huang ◽  
C.W. Lee ◽  
Chan Gyung Park
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Cooling Rate ◽  
High Strength ◽  
Nucleation Site ◽  
Polygonal Ferrite ◽  
Low Alloy Steels ◽  
Low Carbon ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size

Effects of deformation at austenite region and cooling rate on the microstructure and mechanical properties of low carbon (0.06 wt. % C) high strength low alloy steels have been investigated. Average grain size decreased and polygonal ferrite transformation promoted with increasing deformation amount at austenite region due to increase of ferrite nucleation site. Microstructure was also influenced by cooling rate resulting in the development of a mixture of fine polygonal ferrite and acicular ferrite at 10°C/s cooling rate. Discontinuous yielding occurred in highly deformed specimen due to the formation of polygonal ferrite. However, small grain size of highly deformed specimen caused lower ductile-to-brittle transition temperature than slightly deformed specimen.

Controlling Mechanism of Ferrite Grain Size Generated through Large Strain Deformation of 0.15C Steel

2006 ◽  
Vol 503-504 ◽  
pp. 687-692
Author(s):  
S.V.S. Narayana Murty ◽  
Shiro Torizuka ◽  
Kotobu Nagai
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Large Strain ◽  
Low Carbon Steel ◽  
Temperature Deformation ◽  
Specific Reference ◽  
Low Carbon ◽  
Compression Tests ◽  
Controlling Mechanism ◽  
Ferrite Grain Size

During large strain deformation of materials, the width of the initial high angle grain boundaries approaches the order of mean diffusion distances encountered during elevated temperature deformation. Since the evolution of ultrafine grains is attributed to thermally activated processes, the role of interfaces in determining the grain size is significant. In order to investigate into this role, microstructure development in low carbon steel (0.15% C) subjected to large strain deformation was studied with specific reference to the controlling mechanism of ferrite grain size evolution. Plane strain compression tests have been conducted in the temperature range of 773-923K at strain rates of 0.01 s -1 and 1 s-1 and the specimens were deformed to 25% of the original thickness and the Microstructural evolution is studied. Based on the results obtained, diffusion along grain boundaries was found to be the mechanism controlling ferrite grain size in this material processed through large strain deformation.

scholarly journals Strain Hardening of Low-Carbon Steel in the Area of Jerky Flow

2021 ◽  
pp. 65-75
Author(s):  
І. О Vakulenko ◽  
D. M Bolotova ◽  
S. V Proidak ◽  
B Kurt ◽  
A. E Erdogdu ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Carbon Steel ◽  
Strain Hardening ◽  
Low Carbon Steel ◽  
Carbon Steels ◽  
Cold Plastic Deformation ◽  
Low Carbon ◽  
Jerky Flow ◽  
Ferrite Grain Size

Purpose. The aim of this work is to assess the effect of ferrite grain size of low-carbon steel on the development of strain hardening processes in the area of nucleation and propagation of deformation bands. Methodology. Low-carbon steels with a carbon content of 0.06–0.1% C in various structural states were used as the material for study. The sample for the study was a wire with a diameter of 1mm. The structural studies of the metal were carried out using an Epiquant light microscope. Ferrite grain size was determined using quantitative metallographic techniques. Different ferrite grain size was obtained as a result of combination of thermal and termo mechanical treatment. Vary by heating temperature and the cooling rate, using cold plastic deformation and subsequent annealing, made it possible to change the ferrite grain size at the level of two orders of magnitude. Deformation curves were obtained during stretching the samples on the Instron testing machine. Findings. Based on the analysis of stretching curves of low-carbon steels with different ferrite grain sizes, it has been established that the initiation and propagation of plastic deformation in the jerky flow area is accompanied by the development of strain hardening processes. The study of the nature of increase at dislocation density depending on ferrite grain size of low-carbon steel, starting from the moment of initiation of plastic deformation, confirmed the existence of relationship between the development of strain hardening at the area of jerky flow and the area of parabolic hardening curve. Originality. One of the reasons for decrease in Luders deformation with an increase of ferrite grain size of low-carbon steel is an increase in strain hardening indicator, which accelerates decomposition of uniform dislocations distribution in the front of deformation band. The flow stress during initiation of plastic deformation is determined by the additive contribution from the frictional stress of the crystal lattices, the state of ferrite grain boundaries, and the density of mobile dislocations. It was found that the size of dislocation cell increases in proportion to the diameter of ferrite grain, which facilitates the development of dislocation annihilation during plastic deformation. Practical value. Explanation of qualitative dependence of the influence of ferrite grain size of a low-carbon steel on the strain hardening degree and the magnitude of Luders deformation will make it possible to determine the optimal structural state of steels subjected to cold plastic deformation.

Dynamic Recrystallization of Ferrite in Low Carbon Steels

2007 ◽  
Vol 558-559 ◽  
pp. 617-622 ◽  
Author(s):  
Zu Qing Sun ◽  
Long Fei Li ◽  
Wang Yue Yang
Keyword(s):  
Carbon Steel ◽  
Dynamic Recrystallization ◽  
Low Carbon Steel ◽  
Carbon Steels ◽  
Low Carbon ◽  
Compression Tests ◽  
Hollomon Parameter ◽  
Low Carbon Steels ◽  
Continuous Dynamic Recrystallization ◽  
Continuous Dynamic

Dynamic recrystallization(DRX) of ferrite in low carbon steels was investigated by hot compression tests at temperatures of 550 to 700oC at strain rates of 0.001 to 10s-1. The results indicate that DRX of ferrite can occur in low carbon steels and lead to grain refinement. With increasing Zener-Hollomon parameter Z, its mechanism changes from discontinuous dynamic recrystallization to continuous dynamic recrystallization, the turning point is approximately at Z=1×1016s-1 for a low carbon steel with 0.171wt% C. The results also indicate that changing the minor constituents of the low carbon steel from pearlite colonies to fine cementite particles has an effect on promoting DRX of ferrite, and the increase of Mn content and the presence of tiny Nb precipitates have opposite effects respectively. However, all these changes are of benefit to the refinement of recrystallized grains.

Effect of Asymmetric Rolling with Cone-Shaped Rolls on Microstructure and Tensile Properties of Low-Carbon Steel

2015 ◽  
Vol 1105 ◽  
pp. 149-153
Author(s):  
Toleu K. Balgabekov ◽  
Eldar M. Azbanbayev ◽  
Aristotel Z. Isagulov ◽  
Diana A. Isagulova ◽  
Nurlybek B. Zakariya ◽  
...  
Keyword(s):  
Grain Size ◽  
Carbon Steel ◽  
Tensile Properties ◽  
Low Carbon Steel ◽  
Middle Layer ◽  
Low Carbon ◽  
Asymmetric Rolling ◽  
Fine Grain ◽  
Average Grain Size ◽  
Different Temperatures

The effect of asymmetric rolling with cone-shaped rolls on ultra-fine grain evolution was investigated. To do this, low-carbon steel containing 0.15 % C (mass fraction) billet (h|b|l = 10|45|100 mm3) with the initial average grain size of 60 μm was deformed up to the thickness of 5mm in cone-shaped rolls with diameters ratio of 1.5, as well as in cylindrical rolls. Rolling was conducted at three different temperatures: 900 °C, 1000 °C and 1100 °C. Four passes of asymmetric rolling in cone-shaped rolls were given to gain thickness of 5 mm with total reduction of 61,7 %. It has been shown that during asymmetric rolling in cone-shaped rolls at low temperature of 900 °C grain size is smaller (0.092 μm – at the surface layer and 0.112 μm – at the middle layer) than that of 1000 °C and 1100 °C. Tensile properties of asymmetrically rolled specimen were much higher (580 MPa) in comparison to symmetrically rolled one (486 MPa).

Modeling Ferrite Grain Size Distributions during the Transformation of Hot Worked Austenite

2005 ◽  
Vol 500-501 ◽  
pp. 403-410
Author(s):  
R. Zubialde ◽  
Beatriz López ◽  
J.M. Rodriguez-Ibabe
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Carbon Steels ◽  
Microalloyed Steels ◽  
Size Distributions ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Grain Size Distributions ◽  
Ferrite Grain Size

A model has been developed to predict the ferrite grain size distribution resulting after the austenite to ferrite transformation in slowly cooled low carbon steels. The model uses the austenite grain size distribution present before transformation as input and provides the size distribution of ferrite grains at any instant in the transformation range, whether the microstructure is partially either completely transformed. The model is based on empirical equations relating the mean austenite and ferrite grain sizes and log-normal shape grain size distributions. A validation of the model was carried out in the laboratory by torsion tests for Nb and Nb-V microalloyed steels.

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