Extra Low Carbon Steel Research Articles

Comparison of contamination by non-metallic inclusions in continuous cast slabs of special low carbon steel

The paper studies and compares the macrostructure quality of continuously cast slabs of extra low carbon steel grades DX54D, DX56D, DX57D and 006/IF during casting on a curved-type CCM with and without a vertical section. For this purpose the array of production data of casting of steel of the above mentioned grades, totaling 383 melts, was studied. At the same time, 149 melts were cast on four CCMs (conventionally named A, B, C, D) of curvilinear type with a base radius of 8 m, and 234 melts – on a machine of curvilinear type (E) with a base radius of 11 m and a vertical section of 2.7 m length. Contamination of the cast metal with non-metallic inclusions was assessed metallographically by the degree of development of the defect “point heterogeneity”. The presence of a vertical section allows to reduce the degree of development of point heterogeneity from 1.29 to 0.75 points – by 0.54 points or by 41.9% (relative). With a probability of 99.9% we can assert that the difference between the average values of point heterogeneity is not random and is limited by the presence of the vertical section of the CCM

Facilitating the occurrence of dynamic recrystallization in plain extra low-carbon steel by warm asymmetric rolling

The occurrence of dynamic recrystallization in warm rolling of plain extra-low carbon steel was examined by applying 75% thickness reduction in a single pass. The investigated temperature range was ambient to 700 °C. Results show apparently dynamic recrystallization remains absent in symmetric rolling below 600 °C. Nevertheless, dynamic recrystallization not only just occurs but accelerates as the condition of warm rolling changed from symmetric to asymmetric condition. The analysis of grain internal disorientations and geometrically necessary dislocation densities by High-angular Resolution on-axis Transmission Kikuchi Diffraction (HR-TKD) allowed to identify the type of dynamic recrystallization and its evolution through the warm temperature range. New grains formed by either continuous or discontinuous dynamic recrystallization are preferentially orientated according a typical shear texture up to 600 °C in the case of asymmetric rolling. Above 600 °C, dynamically recrystallized grains produce restrengthening in the rolling texture as well as in the overall texture.

Interpretation of the magnetic susceptibility behaviour of soft carbon steels based on the scaling theory of second order phase transitions for systems with supercritical disorder

The experimental magnetic susceptibility curves of several soft steel grades, like interstitial free (IF) or low carbon (LC) steels, can be interpreted within the framework of universal scaling functions obtained for systems with quenched disorder, such as the one described by the random field Ising model with supercritical disorder. Mean-field theory (both scalar and site-dependent) is used to explore the behaviour at the proximity of the coercive field, and explicit expressions are derived. As a result, the susceptibility values close to the coercive field can be approximated to a good extend by a Lorentzian function. Theoretical results are compared against a number of experimental curves obtained from interstitial free (IF) and extra low carbon (ELC) steels subjected to isothermal annealing.

Effect of Carbon Content on Microstructure, Properties and Texture of Ultra-Thin Hot Rolled Strip Produced by Endless Roll Technology.

In order to make a comprehensive comparison between ultra-thin hot rolled low carbon steel (LC) and extra low carbon steel (ELC) produced by endless roll technology and explain the differences, a detailed investigation into the microstructural characterization, characteristics of cementite and precipitates, mechanical properties, internal friction peaks, texture characterization by an X-ray powder diffractometer and electron backscatter diffraction, and formability including earing behavior, hole expanding ratio and V-shaped bending properties was carried out with different carbon content for 1.0 mm thickness ultra-thin hot rolled strip produced in endless strip production line. The experimental results indicate that the microstructure of both is composed of multi-layer areas with different grain sizes and thicknesses, the strength and elongation of LC are higher than that of ELC, but the content of solid solution carbon atoms and r of ELC are higher than that of LC, at the same time, the formability of ultra-thin strip ELC is better than that of LC mainly related to the content of {hkl} <110> and {111} <112> of ELC was higher than those of LC. The mechanical and formability properties of ultra-thin hot rolled strip by endless roll technology can meet the requirements of replacement cold rolled strip by hot rolled strip.

A Study on the Bake Hardenability of a Ti-Nb Stabilized Extra Low carbon Steel

Yakıt t&amp;amp;uuml;ketimini d&amp;amp;uuml;ş&amp;amp;uuml;rmek ve bu şekilde egzoz gazlarının &amp;amp;ccedil;evreye verdiği zararı en aza indirmek amacıyla otomotiv g&amp;amp;ouml;vde ağırlığının azaltılması son yıllarda otomotiv sanayindeki en &amp;amp;ouml;nemli beklentilerden birisidir. Arzu edilen &amp;amp;ouml;zellikler fırınlama sırasında sertleşen &amp;amp;ccedil;eliklerle elde edilmiştir. Ancak fırınlama sırasında sertleşme &amp;amp;ouml;zelliği &amp;amp;ouml;n deformasyon miktarı ve fırınlama sıcaklığına bağlı olarak değişmektedir. Bu &amp;amp;ccedil;alışmada Ti-Nb ile stabilize edilmiş &amp;amp;ccedil;ok d&amp;amp;uuml;ş&amp;amp;uuml;k karbonlu bir &amp;amp;ccedil;elik sacın fırınlamayla sertleşme &amp;amp;ouml;zelliği &amp;amp;ouml;n deformasyon miktarı ve fırınlama sıcaklığına bağlı olarak incelenmiştir.

Effect of strain path change on texture and microstructure evolution in asymmetric rolled extra-low carbon steel

In asymmetric rolling, it is possible to introduce a shear strain component in the bulk of the sheet. In this work, the rolling sequence was changed in alternate passes by rotating the sheet about its three axes: the rolling, transverse and normal directions. Depending on the strain path, the shear component can be increased or even be cancelled. The objective of changing the strain path is to investigate the consequences of the varying imparted shear introduced by the asymmetric rolling on the deformed microstructure and the texture evolution. Comparisons were made with respect to the monotonic rolling case. It has been found that when the strain path change is reducing the shear, there are more differences in the microstructure with monotonic rolling than in shear-reinforcement strain path sequence. The texture evolution as well as the grain boundary characteristics are also very sensitive to the strain path. Severe rolling was examined up to 99% rolling reduction. It has been found that there was an increase in the average grain size in the 95%–99% rolling stage. This effect can be related to the texture-evolution induced grain coarsening phenomenon.

Metallurgical Characterization of the Interfaces in Steel Plates Clad with Austenitic Steel or High Ni Alloys by Hot Rolling

An integrated experimental-theoretical approach to the metallurgical characterization of the interfaces in steel plates clad by hot rolling is proposed. Three different couplings of materials have been studied: ASTM A 515 Gr.60 low carbon steel clad with austenitic stainless steel AISI 304L; extra low carbon steel ASTM A283 clad with high Ni content Alloy 59; and, low carbon steel AISI 1010 clad with Cu-Ni Monel 400. Experimental investigations, which are addressed to analyse the microstructural changes near the interfaces and identify the present phases, have been carried out through scanning electron microscopy (SEM) observations, microanalytical measurements by energy dispersive spectroscopy (EDS), and Vickers microhardness tests. In all of the cases examined, the zones that are affected by detrimental microstructural changes results in being considerably less thick than the overall cladding layer. Simulations that are based on theoretical diffusion modelling have been integrated to the experimental characterization by introducing a cladding parameter that acts on the diffusion bonding efficiency, in order to evaluate the effects of process temperature and time variations on diffusion bonding efficiency and stability. In particular, this analytical investigation has shown how the shorter is the duration of the diffusion transient and the higher the temperature, the lower results the sensitivity of the diffusion processes to temperature fluctuations.

Tailoring One-Pass Asymmetric Rolling of Extra Low Carbon Steel for Shear Texture and Recrystallization.

Systematic single pass rolling experiments were carried out at room temperature on extra low carbon steel by varying the roll diameter ratio between 1:1 to 1:2 and thickness reduction per pass in the range of 20–75%. The aim of this study was to define the conditions under which the rolling texture can transit into a shear texture. The consequences for grain fragmentation, tensile strength, recrystallization texture, and grain growth kinetics were also studied. It was found that in a certain range of thickness reduction per pass and asymmetric ratio, an effective rotation towards the shear texture takes place in conventional rolling. The value of the shear coefficient factor (shear strain rate/rolling strain rate) in asymmetric rolling depends on the selection of thickness reduction per pass. The measured value of shear coefficient was found to be independent of the number of passes used in asymmetric rolling. The consequence of arising shear textures is an acceleration of grain fragmentation. After rapid heat treatment, both tensile strength and recrystallization kinetics of asymmetric rolled sheets showed merits over the conventional rolling. Only the evolved Goss orientation from asymmetric conditions of deformation shows higher stability than any other preferred shear texture components after complete recrystallization.

Effects of Processing Conditions on Texture and Microstructure Evolution in Extra-Low Carbon Steel during Multi-Pass Asymmetric Rolling.

Multi-pass rolling was carried out on extra-low carbon steel at room temperature by imposing different ratios of asymmetry in the roll-diameters as well as by conventional mode. The aim of this study is to understand the effect of shear deformation due to the asymmetric conditions on the development of the rolling texture and the possibilities of propagating the shear deformation into the mid-thickness area of the sheet. The trends of the measured texture developments in both symmetric and asymmetric rolling indicate their dependence primarily on the stability and fraction of the Goss {110}<001> and the rotated cube {001}<111> orientations. The effects of asymmetry conditions were further examined on the microstructure evolution and were correlated to the increased orientation inhomogeneity and grain fragmentation. Both texture and microstructure development showed their dependence on the applied thickness reduction per pass, on the total thickness reduction of the sheet as well as on the degree of the imposed asymmetry. It was found that shear textures can be obtained by asymmetric rolling at conditions where all three parameters—asymmetry ratio, strain in one pass, and the total accumulated strain—are as large as possible.

Effect of Annealing Temperature and Coiling Temperature on r-value of Nb and B-added Extra Low-carbon Steel

When a welded can body is expanded in the pail can manufacturing process, it shrinks in the direction of can height. The change of the can height is influenced by the r-value of the steel sheet.

Waste steel scrap to nanostructured powder and superior compact through powder metallurgy: Powder generation, processing and characterization

The present paper reports fabrication of superior steel compact using nanostructured steel powder generated from industrial steel scrap. Extra low carbon and low carbon steel powders with size of submicron were generated from industrial waste by planetary milling for 5h. The milled powders are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and hardness. Finest particles are obtained after 3h of milling in both cases. In case of extra-low carbon steel, cold welding and agglomeration is observed after 5h of milling. However, in case of low carbon steel, no such phenomenon is visible after 5h of milling. The effect of ball to powder weight ratio (BPR) is studied using BPR of 12:1 and 6:1 for low carbon steel chips by milling for 3h. A higher yield of 94.29% is obtained when milling conducted at BPR 12:1 than 86.94% yield at BPR 6:1 after milling low carbon steel for 3h. Lower average particle size of 5–10μm is obtained when milling is carried out at BPR 12:1 than 15–20μm at BPR 6:1. In case of low carbon steel, % yield increases from 94.29% to 99.14% as milling time increases from 3 to 5h. Yttria free and 1wt% yttria dispersed both extra-low carbon and low carbon steel powders are cold compacted and conventionally sintered at 1100°C for 1h. Significant improvement in the hardness was achieved through addition of small amount of yttria with both the steel powder generated from the steel scrap.

Development of Micro-shear Fatigue Test and its Application to Single Crystal of Pure Iron

In this study, a new fatigue testing method under shear and axial loading was developed for small specimens (3mm long and 0.3mm thick). The method was applied to a single crystal of pure iron and extra-low carbon steel in order to investigate the effect of shear and normal stress on cyclic slip activity. The specimen was sufficiently small to be prepared from a single crystal, aiming at a specific slip system in the shear loading direction. Moreover, the specimen had a single edge notch, which was designed to generate both pure shear stress and normal stress. Using this testing method, shear fatigue strength with a static normal stress on the slip system ▪[111] was evaluated, and the fatigue strength was compared with that of polycrystalline ferrite steel with static axial loading.

溶接缶用Nb-B複合添加極低炭素鋼のr値に及ぼす焼鈍温度と巻取り温度の影響

When the welded can body is expanded in the pail can manufacturing,it shrinks in the direction of can height.

溶接缶用Nb-B複合添加極低炭素鋼のr値に及ぼす冷延圧下率の影響

溶接缶用Nb-B複合添加極低炭素鋼のr値に及ぼす冷延圧下率の影響

肩部回転ダイを用いた波面容器の成形性

The formability of the corrugated cup was investigated by the deep drawing process. The die having rotating shoulder was used to enhance the functionality of the drawn cup. The blank is formed into a cylindrical cup by means of a punch that presses the blank into the die cavity. To form the corrugated surface, the bearing balls were set on the shoulder of a die. The balls rotate freely during forming. The deep drawing process was performed using an oil hydraulic press at a forming speed of about 10 mm/min. The blanks were commercially extra-low carbon steel SPCC, stainless steel SUS304, pure cooper C1100, and pure titanium TP340. The initial diameter and thickness of the blank are 70 to 100 mm and 0.5 mm. The lubricant used was the solid powders of molybdenum disulfide. The metal sheets were successfully drawn without the cracks. It was found that the corrugated cups were successfully formed by using the roller die.

Segmentation of 3D EBSD data for subgrain boundary identification and feature characterization

Subgrain structures formed during plastic deformation of metals can be observed by electron backscatter diffraction (EBSD) but are challenging to identify automatically. We have adapted a 2D image segmentation technique, fast multiscale clustering (FMC), to 3D EBSD data using a novel variance function to accommodate quaternion data. This adaptation, which has been incorporated into the free open source texture analysis software package MTEX, is capable of segmenting based on subtle and gradual variation as well as on sharp boundaries within the data. FMC has been further modified to group the resulting closed 3D segment boundaries into distinct coherent surfaces based on local normals of a triangulated surface. We demonstrate the excellent capabilities of this technique with application to 3D EBSD data sets generated from cold rolled aluminum containing well-defined microbands, cold rolled and partly recrystallized extra low carbon steel microstructure containing three magnitudes of boundary misorientations, and channel-die plane strain compressed Goss-oriented nickel crystal containing microbands with very subtle changes in orientation.

Cu첨가 극저탄소강 냉간압연재의 초기 재결정 거동에 미치는 변형미세조직의 영향

Cu첨가 극저탄소강 냉간압연재의 초기 재결정 거동에 미치는 변형미세조직의 영향

Nb-B複合添加極低炭素鋼の熱間延性に及ぼす窒素の影響

Nb-B複合添加極低炭素鋼の熱間延性に及ぼす窒素の影響

Technical Investigation into the In-situ Electron Backscatter Diffraction Analysis for the Recrystallization Study on Extra Low Carbon Steels

Technical investigation to figure out the problems arising during in-situ heating electron backscatter diffraction (EBSD) analysis inside scanning electron microscopy (SEM) was carried out. EBSD patterns were successfully acquired up to <TEX>$830^{\circ}C$</TEX> without degradation of EBSD pattern quality in steels. Several technical problems such as image drift and surface microstructure pinning were taking place during in-situ experiments. Image drift problem was successfully prevented in constant current supplying mode. It was revealed that the surface pinning problem was resulted from the <TEX>$TiO_2$</TEX> oxide particle formation during heating inside SEM chamber. Surface pinning phenomenon was fairly reduced by additional platinum and carbon multi-layer coating before in-situ heating experiment, furthermore was perfectly prevented by improvement of vacuum level of SEM chamber via leakage control. Plane view in-situ observation provides better understanding on the overall feature of recrystallization phenomena and cross sectional in-situ observation provides clearer understanding on the recrystallization mechanism.

The Investigation on Wire Rod Materials of Low Carbon Steels and Extra Low Carbon Steels

In this study, three kinds of rolled wire rod materials constantly used on screws and bolts are concerned. The relation among mechanical properties, phase ratios, micro-structures and grain sizes is investigated on the wire materials of low carbon steels and extra low carbon steels. Also the Electron Microscope and Energy Spectrum analysis are applied to distinguish the type of Precipitation phase. The results are shown that the precipitation phase of titanium nitrides and titanium carbides exist in the extra low carbon steel so that the hardness ratio of the wire materials with extra low carbons after cold forming is higher than that of the wire materials with low carbons for around 10%. In addition, The wire rod materials with course ferrite grains mainly added by titanium elements in extra low carbon steels could be made as the wire materials for cold processing and it still kept good ductility not necessary to be softened under heat treatment. So in the research of function comparisons, to save cost expenses through cold forming without annealing process is expected.