Carbon Steel Bars Research Articles

Strain distribution and microstructural evolution in multi-pass warm caliber rolling

The three-dimensional finite element-analysis and electron backscattered diffraction analysis are used to study quantitative correlation between effective strain and deformed microstructure in low carbon steel bars fabricated through multi-pass warm caliber rolling. The strain imposed in the rolled bars has a distribution with maximum at around corners, and large strain of over 5.7 is introduced into corners when nominal reduction in area is 89%. The area of around corners introduced strain over 5.7 is filled with the ultrafine ferrite grains of below 680 nm. It is shown that microstructural parameters, the fraction of high angle grain boundaries (HAGBs) and the average misorientation, not only depend on strain imposed but also local reduction in area.

Crystallographic Texture of Warm Caliber-rolled Low Carbon Steel

The evolution of crystallographic texture with effective strain up to 5.9 is studied in low carbon steel bars fabricated using multi-pass warm caliber rolling. Three-dimensional finite element analysis was carried out to evaluate distributions of effective strain accumulated and strain components introduced with each pass through the rolled bars. The texture at characteristic deformation sites on the cross section in the bars was analyzed using the electron back-scattered diffraction method. Although the texture in the area around the center is dominated by a strong α-fiber (RD||〈101〉), in the other two areas, an α-fiber texture is not produced. It is clarified that this difference depends on three deformation modes during rolling. Consequently, the areas around the corners, where effective strain of over 5.7 is introduced, are filled with ultrafine ferrite grains of below 680 nm, and the texture in the areas is random regardless of the increase of the effective strain under a bi-directional simple compressive condition.

Distortion and Residual Stress Behavior of Super-High Frequency Induction Hardened Carbon Steel Bar with Small Diameter

Distortion and Residual Stress Behavior of Super-High Frequency Induction Hardened Carbon Steel Bar with Small Diameter

Interaction of steel with pure Al, Al–7Si and A356 alloys

Carbon steel bars were dipped in aluminum alloy melts for different periods of time. A reactive iron–aluminum intermetallic layer grew at the interface between the melt and the steel substrate. This reactive layer was mainly composed of intermetallic Fe–Al (Fe 2Al 5) and its thickness was influenced by dipping time (3–60 min), surface roughness (0.74 μm versus 0.07 μm) and carbon content (0.2–0.4 wt%) of the steel bars and the elements (mainly Si and Mg) added in the aluminum alloys. An oxide film, which existed at the interface between steel bar and melt, hampered the Al–Fe reaction. In comparison with a pure Al melt, the thickness of the reactive layer of the Al–7Si alloy melt decreased after a very short dipping time (3 min), increased following an increase in the dipping time (10 min) then decreased after a long dipping time (>20 min). The thickness of the reactive layer of a 1040 steel bar dipped in an A356 alloy (Al–7Si–0.4Mg) melt for a given dipping time at 973 K, was the narrowest among all melts studied; including pure Al, Al–7Si, Al–1Mg and Al–7Si–0.4Mg alloys.

Aspects of behaviour of CFRP reinforced concrete beams in bending

The corrosion of steel poses a serious problem to the durability of reinforced concrete structures and fibre reinforced polymer (FRP) has emerged as a potential alternative material to the traditional steel. The results of a test series consisting of carbon FRP (CFRP) and steel bars reinforced concrete beams are reported in this paper. The results indicated that the behaviour of CFRP and steel reinforced beams was similar in many aspects. Both type of beams failed in their predicted modes of failure. The strength design method underestimated nominal moment capacity of CFRP reinforced beams. The deflection of CFRP reinforced beams was satisfactory at service load level, corresponding to theoretical load capacity. The deformability factor of CFRP reinforced beams was more than 6 indicating their ductile nature of failure.

Bar diameter as an influencing factor on temperature in turning

Factors such as cutting speed, feed rate, tool material, etc., are well known to have an effect on tool wear in metal turning. However, reliable methods of wear prediction over a broad spectrum of cutting circumstance remain elusive, suggesting that not all factors have been recognised as significant and thus considered. This paper demonstrates that one such factor is bar diameter. The findings are analysed in three separate ways. All tests were performed under identical cutting conditions, i.e. cutting speeds were constant as well as the feed rate and depth of cut, also the same bar was used except for varying the bar diameter. All experiments were performed in single point turning on solid carbon steel bar (BS970 080A42), by using uncoated ISO (4957) (BS 4659 BT42) HSS insert.

Substructural evolution during cyclic torsion of drawn low carbon steel bars

Strain softening effects have been previously observed in drawn low carbon steel bars as a result of cyclic torsion experiments. In this paper, the substructural aspects related to the phenomenon have been investigated. Single pass drawn bars were subjected to a quarter, to a half, to a full torsion cycle and to 10 such cycles. Transmission electron microscopy revealed the development of extended microbands crossing the former dislocation arrangement of the drawn metal, which evolves to a rectangular shaped subgrains structure as torsion deformation is conducted.

海洋環境下におけるステンレス鉄筋の適用性に関する検討

For the application to port concrete structures under marine environment, corrosion-resistant property of three types of stainless steel bars (SUS430, SUS304 and SUS316) in concrete was studied by immersing each steel bars in the simulated pore solution in concrete and exposing concrete specimens, in which each steel bars was embedded, under marine environment. Results obtained are as follows. 1. In the sound concrete region without crack, no corrosion was observed in all stainless steels (SUS430, SUS304, SUS316) under high chloride ion content which was around 15 kg/m3 in concrete. Therefore, it can be judged that the chloride threshold level for corrosion of these stainless steels is more than 15 kg/m3. 2. In the cracked concrete region, no corrosion was observed in two types of stainless steel (SUS430 and SUS316). However, very small corrosion was observed in the only crack region on SUS304. This reason is considered to be larger crack width than SUS430 and SUS316. This indicates that some large crack width can not be allowed in case of the stainless steel which has similar corrosion-resistant property to SUS304. It is necessary to study on the maximum allowable crack width. 3. In case that stainless steel bar is applied to port concrete structures under marine environment, the life cycle cost can be lower than the case of carbon steel bar in some specific cases.

Magnetic Characteristics of Architectural Materials for Non-magnetic Buildings

The magnetic properties of several major materials used for buildings are measured at room temperature using SQUID magnetic sensor. The magnetization of SUS304 plate, SUS304 hinge with and without plastic deformation, and bent SUS304 plate were determined. It was observed that saturation magnetization of the plastically deformed portion of the hinge is twenty times higher than that of the undeformed portion of the hinge. Also, the magnetization was found to increase as the bending angle increases suggesting that the magnetic properties of SUS304 are significantly enhanced by plastic deformation. Nonmagnetic bar, cement and sand have magnetization less than SUS304 plate but ferromagnetic carbon steel bar shows high magnetization.

The effect of cyclic straining on the drawing stress of low carbon steel bars

The investigations covering the work hardening behavior of metals under strain path changes have pointed out the possibility of employing the strain softening phenomenon in sequential forming operations, specially in the case of cyclic straining. In this paper, the effects of cyclic torsion on the drawing stress of low carbon steel bars have been investigated. The material was drawn up to five passes. Cyclic straining was carried out between the last two stages of drawing and between every drawing pass. The substructural aspects of the bars were also analyzed. Cyclic torsion led to a decrease in the drawing stress values, whose magnitude depended on the number of forming passes considered in the experiment. The results also showed the occurrence of non-cumulative strain softening effects. Dislocation restructuring was found to be the softening mechanism related to the results.

High strength and low yield ratio carbon steel bar processed by thermomechanical rolling

Adding alloying elements or refining grain size are the common means to increase the strength of steels. By refining ferrite grains down to ~1μm through thermomechanical rolling, a high strength and low yield ratio (the ratio of yield strength to tensile strength) steel bar with good impact toughness has been developed from an ingot with a similar chemical composition to that of mild steel. The steel bar consisted of large ferrite grains (1 – 15μm), small ferrite colonies (smaller than ~1μm), and martensite. The tensile strength, 0.2% offset yield strength, yield ratio, uniform tensile elongation, and elongation up to fracture of the developed steel were: 856 MPa, 478 MPa, 0.558, 11.6%, and 19.1%, respectively. The absorbed energy in Charpy impact test at -40°C was 134 J. The toughness and strength of the steel can be adjusted by varying the volume fractions of the large ferrite grains, small ferrite colonies, and martensite.

A force model of turning stainless steel with worn tools having nose radius

To study cutting forces, tip’s surface temperature, the mechanism of secondary chip and main chip formation when turning stainless steel with a chamfered main cutting nose radius tool are considered to have pre-wear. A holder with special tools and geometry are designed first. Secondly, the tool holders made of medium carbon steel bars are milled and ground to make them fit to various specifications. Finally, the tip’s mounting in the tool holder are ground to wearing depth measured with a toolmaker’s microscope and a new force model incorporating a tool pre-wear factor using the variations of shear plane areas cooperating with tool pre-wear situations is made. After the cutting processes have occurred, more wear factors of tool are considered in the force model. For successfully predicting cutting forces, however, shear plane areas vary due to the wearing effects of the tool edge in cutting stainless steel.

Study of microstructure, mechanical properties, and magnetization process in low carbon steel bars by Barkhausen emission

Correlation between Barkhausen emission (BE) signal, microstructure and mechanical properties of a series of low carbon steel bars after receiving different heat treatments are studied for the purpose of further developing the nondestructive BE technique to monitor the stress–strain characteristics of steel components. It is found that the BE signal, which is proportional to the number of unpinning events of domain walls (DW), is more intense in samples with small grains which have been annealed at lower temperatures, than in those with large grains which have been annealed at higher temperatures. The small-grain samples have larger BE signals, because they have large fractional volume of grain boundaries that act as sites for the DW unpinning. A qualitative model is proposed to describe the BE signal obtained from these ferritic steel samples. BE measurements are also made in-situ on each sample while it is under increasing tension. The BE signal increases in sample under tension. In the case of small-grain sample, the increase is mainly due to the re-orientation of domain configurations that facilitates the magnetization process. In the case of large-grain sample, tensile stress re-orients the domain configurations as well as creating new DWs that increase the number of unpinning events. In this work, it is also found that the BE–strain plots of the steel bars annealed at temperatures ranging from room temperature to 600 °C exhibit behaviors which are similar to their corresponding stress–strain curves.

Mechanical properties relationships in V‐ and Ti‐microalloyed steels

Microalloyed steels are characterised by their mechanical properties. Nowadays, they are used in a wide range of applications. The convenience and simplicity of hardness tests permit to obtain economically and rapidly information on the structure of steels and control their treatments. This study has been carried out to derive equations for prediction of the mechanical properties of microalloyed steels by hardness measurement. With this objective, V‐ and Ti‐microalloyed plain carbon steel bars were melted, hot rolled, heat treated and machined for the measurement of their mechanical properties and to reach a correlation between both ultimate tensile strength, yield strength and uniform elongation and Vickers hardness. The obtained data were treated using different mathematical fittings. They are mathematically treated as groups according to the heat treatment processes and as one group. The derived equations show good agreement with each other and with most of the little relations found in the literature. General equations for deducing mechanical properties values from the easily measured Vickers hardness values were derived. The equations derived from one group without regarding the treatment processes are more reliable.

Nondestructive evaluation of carbon contents and microstructures in plain carbon steel bars by Barkhausen emission

Plain carbon steels with different carbon contents have been widely used in industry. There is a pressing need for the nondestructive inspection of steel parts during their fabrication and when they are in service. Barkhausen emission (BE) is one of the nondestructive testing methods that is being used. Recently, we find that the following parameters of the BE signals depended strongly on the carbon content in steel sample, namely, the rising slope of the BE profile, the root-mean-square of the signals, and the half-maximum-width of the profile. The values of these parameters increase as the amount of carbon in the sample increases. The dependence is similar to that of the mechanical hardness on the carbon contents in the samples.

Work softening of drawn low carbon steel bars

The work hardening of metals subjected to complex processing paths is different from that in monotonic deformation. Changes in the deformation mode can promote transients in the strain-hardening rate, leading to anomalous softening or hardening of the material. This paper investigates the influence of strain path changes on the tensile behavior of drawn 0.12% steel rods. Annealed or predrawn specimens were submitted to cyclic twisting and then tested in tension. The results show that the cyclic deformation causes changes in the mechanical behavior of the metal, and the effect will depend on the previous "history" of the material. Cyclic twisting causes hardening in annealed samples, but leads to softening of the drawn bars. These phenomena are in line with the corresponding substructural aspects.

Study of eddy current power loss from outer-winding coils of a magnetic position sensor

The present analysis is concerned with eddy current power loss of a magnetic position sensor, which arises from a non-uniform flux linkage distribution between magnetic material and position sensor. In the paper, a magnetic position sensor system is simplified to be an outer-winding coil along the axial direction of a low carbon steel bar, and developed a numerical model to compute the electrical characteristics by an excited current source. According to the simulated and measured data in this proposed model from 2.52 to 11.37 Oes, eddy current power losses of conducting material have a variation of 6.1% and 9.77%, respectively. Finally, the phases of waveform of the induced output voltage will also be obtained in the conducting material, and have a variation of 3.68% obtained by using the current source in the proposed model.

Effect of temperature and deformation histories on grain coarsening in medium carbon steel

Hot rolling of medium carbon steel bars using a prototype mill and numerical analyses were carried out to examine quantitatively the effect of temperature and strain throughout rolling on the final grain size of the product. Cross-sections of the rolled bars were subjected to optical microscopy to investigate the effect of the instantaneous decrease in temperature owing to contact with the roll groove on grain coarsening in the vicinity of the bar surface. By analysing the grain size after rolling, the temperature history throughout rolling, and the equivalent plastic strain after rolling, it was found that the instantaneous decrease in temperature owing to contact did not affect grain coarsening unless the final values of the temperature and strain fell within a narrow band of values meeting the criteria for grain coarsening. Referring to both the present results and the authors' previous studies, criteria have been established for the prevention of grain coarsening in steel bar sizing operations.

A force model for nose radius worn tools with a chamfered main cutting edge

The three-dimensional cutting forces for nose radius tools with a chamfered main cutting edge incorporated with a tool-worn factor are presented in this paper. The variations in shear plane areas occurring in the tool-worn situation are used. The results obtained from the proposed model shows good agreement with the experimental data on both chip formation as well as cutting forces. In the experimental work the throwaway tips are locked onto the pocket of the tool holder. The holders for special tools are designed first. Next, the tool holders are manufactured by using medium carbon-steel bars and the mounting tips are designed based on various specifications. Finally, the nose radius tips mounting in the tool holder are ground to a wear depth, and the worn tool dimensions are measured by using a profile projector. The shear area and the friction area are calculated accordingly. Then the three-dimensional cutting forces will be obtained from those data.

Turning of stainless steel with worn tools having chamfered main cutting edges

A force model is proposed in this study for a single-point tool with a chamfered main cutting edge incorporating a wear factor. The variations of shear plane areas occurring in the tool-worn situation are also used. Cutting experiments are conducted on stainless steel bars and the experimental data correlated closely with the theoretical values. A preliminary discussion is also made of the design of special tool holders and their geometrical configurations. The tool holders were milled using medium carbon-steel bars and these holders with the mounting tips were ground to fit various specifications.