Phases transformation textures in steels

2004 ◽  
Vol 120 ◽  
pp. 137-144
Author(s):  
C. Cabus ◽  
H. Regle ◽  
B. Bacroix
Keyword(s):  
Phase Transformation ◽  
Thermomechanical Processing ◽  
Texture Evolution ◽  
Residual Austenite ◽  
Carbon Steels ◽  
Low Carbon ◽  
Orientation Relationships ◽  
Cold Rolling And Annealing ◽  
Transformation Mechanisms ◽  
Ebsd Technique

Low-carbon steels used for deep-drawability applications have properties which depend greatly on their crystallographic texture. It is therefore important to control the texture evolution during the thermomechanical processing. Until recently, little attention has been paid on the understanding of the textures formation after hot-rolling, which are produced by phase transformation, although it is recognised that they have an effect on the development of the texture in the further process (cold rolling and annealing). Indeed, one of the main difficulties consists in the measurement of texture above ambient temperature, in the austenite range. In the present work, EBSD technique is employed on a low-C steel and a method is proposed to determine local austenite orientation thanks to martensitic one, even if there is no residual austenite in the steel. The orientation relationships between the austenite phase and each of its product phases, here martensite and polygonal ferrite, are analysed and compared. Common Kurdjumov Sachs variants are detected for both phases. Variations in the intensities of these variants are also detected and could be due to the different phase transformation mechanisms, diffusion or shear.

scholarly journals Effects of Double Reduction and Annealing on the Texture during Continuous Rolling of Ultrathin Sheets of Low Carbon Steels

2019 ◽  
Author(s):  
Laura G. Castruita-Avila ◽  
Francisco A. García-Pastor ◽  
Manuel de J. Castro-Roman ◽  
Jesus Emilio Camporredondo-Saucedo ◽  
Fabián Equihua-Guillen ◽  
...  
Keyword(s):  
Texture Evolution ◽  
Low Carbon Steel ◽  
Rolling Process ◽  
Carbon Steels ◽  
Low Carbon ◽  
Double Reduction ◽  
Process Stage ◽  
Texture Intensity ◽  
Pole Figures ◽  
Ebsd Technique

In this paper were analyzed the effects of double reduction and annealing during rolling process on texture evolution in an ultrathin sheet of low carbon steel. Experimental samples were obtained from each process stage. EBSD technique and correlated tools as orientation density functions and pole figures were used to analyze the microstructural changes and the texture. Results show that {111} recrystallized grains were formed during process, reducing dramatically gamma-fibre texture intensity and generating an adequate finished product for deep die stamping.

Surface Microstructure and Texture Evolution during Interrupted Annealing in Ultra Low Carbon Steels

2010 ◽  
Vol 89-91 ◽  
pp. 202-207
Author(s):  
J. Gautam ◽  
Roumen H. Petrov ◽  
Leo Kestens ◽  
Elke Leunis
Keyword(s):  
Phase Transformation ◽  
Surface Texture ◽  
Texture Evolution ◽  
Low Carbon Steel ◽  
Carbon Steels ◽  
Control Surface ◽  
Surface Microstructure ◽  
Low Carbon ◽  
Metal Vapour ◽  
Low Carbon Steels

The austenite-to-ferrite phase transformation, which is an inherent feature of low-alloyed ultra low carbon steels, has scarcely been investigated to control surface texture and microstructure evolution. This paper investigates the systematic evolution of texture and microstructure at the metal-vapour interface during interrupted annealing in vacuum. Interrupted annealing experiments were carried out on three ultra low carbon steel sheets alloyed with Mn, Al and Si. The texture and microstructures have been investigated by X-ray diffraction and SEM-EBSD techniques. These results reveal a very clear variation in the surface texture components as well as in the surface microstructure after BCC recrystallisation and double  transformation interrupted annealing. The recrystallisation texture consists mainly of a <111>//ND fibre, while the transformation texture at the surface exhibits a <100>// ND fibre in combination with components of the <110> //ND fibre. It has been revealed that the latter specific surface texture was present in a monolayer of outer surface grains which were in direct contact with the vapour atmosphere. This observed phenomenon could be explained by considering the role of surface energy anisotropy occurring during phase transformation annealing.

scholarly journals Effects of hot and warm rolling on microstructure, texture and properties of low carbon steel

2011 ◽  
Vol 64 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Roberto Gerardo Bruna
Keyword(s):  
Mechanical Properties ◽  
Thermomechanical Processing ◽  
Low Carbon Steel ◽  
Warm Rolling ◽  
Carbon Steels ◽  
Low Carbon ◽  
Coiling Temperature ◽  
Microstructure And Mechanical Properties ◽  
Cold Rolling And Annealing ◽  
Hot And Cold Rolling

It is well-known that variations in the thermomechanical processing can have a profound effect on the microstructure and mechanical properties of Low Carbon steels. Numerous studies have been published on the effect of composition, slab reheating temperature (SRT), hot rolling finishing temperature (FRT), coiling temperature after rolling (CT), amount of deformation during hot and cold rolling, and annealing temperature on the mechanical properties of LC steels. There are, however, some disagreements in the results presented in the literature. In this work the FRT and CT effects on the microstructure, recrystallization behavior and texture of LC steels rolled under hot and warm-rolling industrial conditions were investigated. The results in terms of the microstructure, crystallographic texture and properties are shown and discussed. In addition, this study will present the possible mechanisms responsible for the microstructure and mechanical properties observed.

Effect of Cool Deformation on the Mechanical Properties of Low C Microalloyed Steels

2008 ◽  
Author(s):  
Jessica Calvo ◽  
Abdelbaset Elwazri ◽  
Dengqi Bai ◽  
Stephen Yue
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
Thermomechanical Processing ◽  
Carbon Steels ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Strengthening Mechanisms ◽  
Rolling Schedule ◽  
Low Carbon Steels ◽  
Carbon Microalloyed

The application of small amounts of deformation at coiling temperatures, i.e. cool deformation, has been shown to be an effective method to improve the mechanical properties of low carbon microalloyed steels. Improvements are related to the effect of cool deformation on strengthening mechanisms such as precipitation, grain refinement and phase transformation. However, it is not clear to what extent mechanical properties will improve when cool deformation is applied after TMP (Thermomechanical Processing). In this work, cool deformation was applied in torsion after a simulation of an industrial rolling schedule to samples of six experimental low carbon steels containing different amounts of Nb, Cu, Mo and Si. In general, it was found that cool deformation improved the mechanical properties of all the steels, and the extent of these improvements was dependent on the chemical composition.

In Situ Measurements of Grain Growth and Recrystallization by Laser Ultrasonics

2013 ◽  
Vol 753 ◽  
pp. 25-30 ◽  
Author(s):  
Matthias Militzer ◽  
Thomas Garcin ◽  
Warren J. Poole
Keyword(s):  
Grain Growth ◽  
Thermomechanical Processing ◽  
Texture Evolution ◽  
Carbon Steels ◽  
Laser Ultrasonics ◽  
Sensor Technology ◽  
Austenite Formation ◽  
Low Carbon ◽  
Potential Applications

Laser ultrasonics for metallurgy (LUMet) is an innovative sensor technology for in-situ measurement of microstructure evolution during thermomechanical processing. This unique sensor has been attached to a Gleeble 3500 thermomechanical simulator for dedicated laboratory studies during processing of steel, aluminum, magnesium and titanium samples. Advanced processing software has been developed for the measurement of grain size and texture evolution from laser ultrasonic signals. Results of austenite grain growth measurements in low carbon steels will be described to demonstrate the capabilities of the LUMet technique. Further, applications of the system to measure recrystallization of ferrite and austenite formation during intercritical annealing simulations of dual phase steels will be presented. The ability to rapidly acquire data both during a single test and for multiple conditions over a range of conditions from different samples has important implications on expediting process modelling and alloy design. Although certain limitations exist, the LUMet technique offers a very reliable characterization platform with a number of potential applications in metallurgical process engineering.

scholarly journals Texture Evolution During the Drawing of Low Carbon Steel

1994 ◽  
Vol 22 (4) ◽  
pp. 261-278 ◽  
Author(s):  
C. Schuman ◽  
C. Esling ◽  
M. J. Philippe ◽  
M. Hergesheimer ◽  
M. Jallon ◽  
...  
Keyword(s):  
Deformation Rate ◽  
Early Stage ◽  
Texture Evolution ◽  
Reduction Rate ◽  
Carbon Steels ◽  
Texture Gradient ◽  
Interstitial Free ◽  
Low Carbon ◽  
Fibre Texture ◽  
Drawing Direction

This study deals with the texture evolution during drawing of interstitial-free low carbon steels under different conditions to study the possible influence of the drawing direction, deformation rate and metal/die friction coefficient. The drawing has been carried out without intermediary annealing, with constant die angle and deformation rate per pass. In all cases, a 〈110〉 fibre texture has been observed at the early stage of deformation (a few percents). The drawing direction, whether alternate or unidirectional, has little effect on texture. Slight differences only in the intensity of peaks on pole figures (PFs) are noted. Alternate drawing leads to higher drawing limits. The grain size affects both the texture and the mechanical properties, which are improved by fine grains. For industrial drawing, i.e. at a high deformation rate, no texture gradient has been clearly observed. Nevertheless, slight differences have been noted in the PF intensities, with generally a slightly sharper texture in the core, compared to the surface. The microhardness tests show no hardness gradient. In slow drawing (low deformation rate), there is a weak texture gradient which disappears at larger deformation. In order to visualize the influence of the metal/die friction, we used a material covered with copper. Results show that at a given reduction rate, the material covered with copper shows peak intensities on the (110) PF which are half these of a material drawn under conventional conditions. The drawing textures of BCC materials always present a 〈110〉 fibre texture. A modeling of the texture evolution during drawing has also been carried out using the Taylor model.

scholarly journals Optimization of Niobium Content in Direct Quenched High-Strength Steels

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 807
Author(s):  
Jaakko Hannula ◽  
David Porter ◽  
Antti Kaijalainen ◽  
Mahesh Somani ◽  
Jukka Kömi
Keyword(s):  
Phase Transformation ◽  
High Strength Steels ◽  
Significant Loss ◽  
Carbon Steels ◽  
Optimum Level ◽  
Low Carbon ◽  
Niobium Content ◽  
Low Carbon Steels ◽  
Finish Rolling ◽  
Different Levels

This paper focuses on understanding the effect of niobium content on the phase transformation behavior and resultant mechanical properties of thermomechanically rolled and direct-quenched low carbon steels containing 0.08 wt.% carbon. Investigated steels contained three different levels of niobium: 0, 0.02 and 0.05 wt.%. The continuous cooling transformation (CCT) diagrams covering cooling rates in the range 3–96 °C/s constructed based on the dilatometer studies showed only a minor effects of Nb on the phase transformation characteristics. In addition, experiments were performed for reheating and soaking the slabs at 1050–1200 °C and the results revealed that for these low-carbon steels, Nb failed to prevent the austenite grain growth during slab reheating. In the case of hot rolling trials, two different finish rolling temperatures of 820 °C and 920 °C were used to obtain different levels of pancaking in the austenite prior to direct quenching. The resultant microstructures were essentially mixtures of autotempered martensite and lower bainite imparting yield strengths in the range 940–1070 MPa. The lower finish rolling temperature enabled better combinations of strength and toughness in all the cases, predominantly due to a higher degree of pancaking in the austenite. The optimum level of Nb in the steel was ascertained to be 0.02 wt.%, which resulted not only in marginally higher strength but also without any significant loss of impact toughness.

Texture Evolution of Tertiary Oxide Scale during Steel Plate Finishing Hot Rolling Simulation Tests

2007 ◽  
Vol 550 ◽  
pp. 557-562 ◽  
Author(s):  
Lucia Suarez ◽  
Roumen H. Petrov ◽  
Leo Kestens ◽  
M. Lamberigts ◽  
Yvan Houbaert
Keyword(s):  
Oxide Layer ◽  
Hot Rolling ◽  
Texture Evolution ◽  
Deformation Behaviour ◽  
Rolling Process ◽  
Columnar Structure ◽  
Protective Atmosphere ◽  
Orientation Relationships ◽  
Complex Deformation ◽  
Ebsd Technique

Thin tertiary scale layers have been grown on ULC steel specimens under controlled conditions. After heating under a protective atmosphere (nitrogen), the samples have been oxidised in air for various oxidation times at 1050°C. These experiments are considered a quantitatively and qualitatively reasonable simulation of the scale formation and growth occurring before hot rolling. Immediately after controlled oxidation, some of the samples were subjected to plane strain compression, in order to simulate the finishing hot rolling process. This approach provided a better insight into the deformation behaviour of the tertiary oxide layer in the first hot rolling pass. The layers produced were examined under the SEM using the EBSD technique for texture characterisation and phase morphology determination. The texture of the deformed oxide scales, originally grown on ULC steel at 1050°C, was determined in order to achieve a better understanding of their complex deformation behaviour. This paper gives a first approach of the study of deformed oxides by EBSD. Strongly textured wustite grains with a clearly pronounced columnar structure were observed after oxidation at 1050°C. As the substrate deformation probably affects the oxide layer, orientation relationships between scale layer and substrate were observed. The detailed EBSD study reveals that the oxide layer can accommodate a significant amount of deformation. The oxide layers exhibit good adhesion to the substrate and remain homogeneous over the thickness after compression.

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