Carbon Steel Bars Research Articles

Transitions in wear mechanisms of alumina cutting tools

Alumina inserts were used to turn medium carbon steel bars in dry, continuous cutting conditions at a cutting speed of 450 m min−1. Three wear mechanisms were identified: plastic deformation-induced necking of asperities; grain spallation; and bulk plastic deformation of alumina. The crater wear land was characterized by spikes nearer the cutting edge and ridges further away because the temperatures and compressive stresses were higher nearer the cutting edge. The crater wear-rate, as measured by the maximum crater depth, was controlled by plastic deformation-induced necking, which was also responsible for the formation of the spikes. The flank wear land was characterized by ridges during the initial stage of machining, formed by the spallation of grains and their subsequent smearing by single glide. As the temperatures and compressive stresses on the flank wear land increased with increasing width of the wear land and machining forces, a transition to a two-zone wear feature (TF) characterized by spikes and ridges occurred, similar to that observed on the rake face. Seizure then followed and a transition in wear rate (TR) was observed in that further increases in the width of the flank wear land occurred by bulk plastic deformation of the to material at a much reduced rate. The present work shows that there exists a transition zone (from TF to TR) in flank wear, sepa the rapid wear mechanism of grain spallation from the slower mechanism of bulk plastic deformation, defined by both machining time and a critical flank wear land width.

Relation between Local Strain and Macroscopic Strain in Static Deformation of Plain Specimens of Isotropic Carbon Steel.

Tensile and torsional tests were carried out on the plain specimens of isotropic carbon steels. One of the materials is an annealed cast carbon steel and the other is a rolled round carbon steel bar (S45C) which was diffusion-annealed. Fine grid lines were drawn on the surface of specimens with a diamond-point needle. The lines were fine enough not to influence the structure of the slip bands. The local strains were measured from the elongated or distorted grids. The local deformations were not uniform in either tension or torsion, and most of the local strains were not the same as the given macroscopic strain. That is, there existed various local strains which were from near zero to two or three times the given macroscopic strain. It showed the minor differences of the variation of local strains between tensile test and torsional test.

機械加工を複合化した精密溶射加工装置の開発(第2報)

A process of plasma spraying combined with machining has been proposed and successfullyemployed to produce alumina coatings of high quality over a plain carbon steel bar. Making useof a clean and active bulk surface which has just been machined is of essence in the proposedclean-cut plasma spraying. Besides, integration of grinding into the spraying, in which thegrinding without coolant is conducted just after spraying, makes a contribution to some extentto raise the bond strength between the coating and the substrate. In order to evaluate thebond strength a scratch test has been performed. When the coated substrate is machined by asharp cutting tool, the scratching force and the damaged area are measured, and a shear bondstrength is estimated. The coating made by the combined method gives higher bond strength andlarger wear resistance as well.

Nonuniformity of Local Strain and Strain Concentration in Static Deformation of Plain Specimens of Rolled Round Carbon Steel Bars.

Tensile and torsional tests were carried out on the plain specimens of rolled round carbon steel bars (S15C, S35C, S45C). Each specimen is regarded as an anisotropic material because it has a banded structure of ferrites and pearlites which were produced by rolling. Fine grid lines were drawn on the surface of specimen with a diamond-point needle. The lines were fine enough not to influence the structure of the slip bands. The local strains were measured from the elongated or distorted grids. The local deformations were not uniform in both tension and torsion, and most of the local strains were not the same as the given macroscopic strain. That is, there existed various local strains which were from near zero to several times the given macroscopic strain. The variety of local strains in torsion was greater than that in tension. The banded structure affected the local strain greatly in torsion, but hardly affected that in tension. Strain concentration in tension was small ; however, in torsion, this was large within the ferrite sandwiched between pearlite bands. When the materials had a clear banded structure and large binding force due to pearlites, the banded structure greatly influenced the local strain in torsion. The result of this study is important to the understanding of the fatigue of plain specimens of rolled round carbon steel bars.

The effect of thermo‐mechanical treatment on The pitting corrosion of reinforcing carbon steel bars

AbstractSteel reinforcing rods with varying amounts of cold work and carbon concentrations (0.06 to 0.45% C) exposed in soil embankments has shown various degrees of pitting corrosion. To understand this pitting process, laboratory investigations on residual stresses, microstructures and potentiodynamic cyclic polarization were undertaken. Analysis of residual stresses in the steels indicated low value of compressive stresses in hot rolled steels and high value of tensile stresses in the cold worked counterparts. Hot rolled steels displayed a slightly better pitting corrosion resistance than cold worked samples which is consistent with the above internal stress pattern. No definite correlation was obtained between the percentage of carbon in the steels and pitting susceptibility. An attempt has been made to define the role of the complex steel‐soil system for pitting corrosion behavior.

Fatigue Limit and Small-Crack Growth Law in Rotating Bending and Torsional Fatigue of Rolled Round Carbon Steel Bars which are Quenched and Tempered.

Rotating bending and torsional fatigue tests were carried out on plain specimens and small-hole specimens of rolled round carbon steel bars which were quenched and tempered. The present specimens are regarded as isotropic materials although the original materials have a banded structure. The fatigue limit ratio between rotating bending and torsional fatigue (τw/σw) in the specimens is different from that in an annealed rolled round carbon steel bar, and is approximately the same as that in isotropic cast carbon steel. We should use isotropic materials in discussing effects of combined stresses on fatigue. In the torsional fatigue tests, crack propagation on plain specimens was of the shear type in the initial stage and of the tension type in the later stage. Cracks of the shear type were generated in both the circumferential and axial directions. The crack growth laws in bending and torsion are expressed by dl/dN∝ σ anl or dl/dN∝τanl. The dependency of 1/Nf on the stress amplitude σa and τa in bending and torsional fatigue is approximately the same as the dependency of the crack growth rate on σa or τa, respectively.

Microstructure of a steel perforated by a metallic jet

The purpose of this work is to present a metallographic study of a carbon steel bar perforated by the impulsive loading of a metallic jet. The results show that the passage of shock waves through the material has strong effects on its microstructure. The development of intense twinning, shear bands, grain growth, and recrystallization was observed.

Effect of lubricant fluid on the burnishing process using a rotating ball-tool

A cylindrical surface of a medium carbon steel bar is burnished using a lathe and using a ball as a tool, ie a ball-tool. The ball-tool is rotated by the drive of a workpiece mounted on the lathe. To investigate the effects of lubricant on the burnishing process, various mineral oils (low viscosity JIS-VG10, and ores containing separately sulphur and phosphorus as additives) are used for six kinds of ball-tool, ie cemented carbide, bearing steel, silicon nitride, silicon carbide, and alumina ceramic ball-tools. The surface of the ball-tool used is also examined for surface damage by a surface profilometer and analysed using electron probe microanalysis and X-ray photoelectron spectroscopy. Tricresyl phosphate used as a phosphorus additive has an excellent effect of reducing roughness of the burnished surface when the cemented carbide, silicon nitride ceramic and bearing steel ball-tools are used.

Microstructural studies of a roll-bonded laminated ultrahigh carbon steel bar

The microstructure and hardness of a metal matrix laminated composite, containing an ultrahigh carbon steel and medium carbon steel, is examined and evaluated. The composite, in the form of a round bar, is made by a novel method using a helical radial-shear rolling process developed in the Soviet Union. The as-hot-rolled laminate is shown to have a high hardness of HV = 500 in the ultrahigh carbon steel region, which is attributable to the fine microstructure consisting of eutectic carbides, a discontinuous network of proeutectoid carbides, and ultrafine pearlite.

冷間引抜鋼丸棒の残留応力

Residual stresses in 0.25% carbon steel and 0.45% carbon steel bar specimens which were cold drawn to cross-sectional reductions from 5 to 29% were measured. The cold drawing was carried out several times by the cross-sectional reduction of about 5% per pass. The residual stresses in the section of specimens after drawing were tensile at the outer part of the specimens, and compressive at the inner part of the specimens. The maximum residual stress at the outer part increased successively with the cross-sectional reduction to about 20%, and decreased over 20%. There are differences in the variation of the normal residual stress distribution with increasing cross-sectional reduction below and over at 20%. The textures in the outer and inner parts of these specimens were measured. The influence of the structure for the occurrence of residual stresses was discussed.

Study of quench cracking of high carbon and chromium steel bar. 4th report. Repeated quenching.

The preceding paper has reported on the numerical evaluation of quench crack susceptibility. The disadvantage of the experimental method has been the assumption of a great number of samples i.e., high cost. This paper deals with a modified method for evaluating quench crack susceptibility. Quenching was repeated n-th times until a crack was generated, using 45 test pieces. The results obtained are discussed and compared with the data presented in the preceding paper. In quench cracking of a high carbon and chromium steel bar, vertical crack value in 1/n crack generation is closely related to the crack percentage, while fin crack value slightly deviates. The residual stresses caused by repeated quench were measured by the X-ray diffraction method. The residual stresses caused by repeated quench were measured by the X-ray diffraction method. The residual stress (tensile stress) on the surface increased with repeat time. It was clarified on the basis of observations using a metallurgical microscope that the repeat of quenching should be less than 34 times.

Study of quench cracking of a high carbon and chromium steel bar. 2nd Report. Effects of interrupted quenching and delayed quenching on quench cracking.

The preceding paper has reported that the increase of polyalkylene glycol (PAG) polymer concentration results in the decrease of fin cracks and increase of vertical cracks because of the low cooling rate of the quenchant. This paper deals with the effects of interrupted quenching and delayed quenching on quenching. The residual stress and hardness were measured by the X-Ray diffraction method and Rockwell hardness tester, respectively. The interrupted quenching method is more effective to prevent cracking in PAG solutions. Immersed for 6seconds in 5% PAG sol. and for 15 seconds in 15% PAG sol., the steel bars exhibited high hardness and residual stress. Delayed quenching is less effective to prevent cracking. As the crack percentage decreases, the hardness and residual stress become lower in the delayed quenching.

Study of quench cracking of a high carbon and chromium steel bar. (1st report Effects of austenitizing temperature and properties of polymer quenchant on quench cracking)

Ouench cracking is generally considered to occur under thermal and transformational stresses. In this paper, some of the quench effects on cracks (fin and/or vertical), hardness and residual stresses of a SUJ 2 bar were examined by using polyalkylene glycol (PAG) solutions. The fin crack by water quenching occurred in all specimens at the austenitizing temperatures higher than 800°C. Similarly, the vertical crack occurred in all specimens at higher than 900°C. The increase in PAG polymer concentration results in the decrease of a fin crack and increase of a vertical crack. The PAG quenchant temperature is closely related to the fin crack, because of the clouding points of PAG solutions. The residual stresses caused by quenching were mearured by the X-ray diffraction method. A considerable tensile stress existed on the surface area of all specimens.

Study of quench cracking of a high carbon and chromium steel bar. (3rd report. Effects of clouding point of polymer quenchant on quench cracking).

The preceding paper has shown that the increase of polyalkylene glycol (PAG) polymer concentration results in a decrease of fin cracks and an increase of vertical cracks, because of the clouding point (81°C) of PAG sol.. This paper deals with the effects of the clouding points of quenchant on the quench cracking of a SUJ 2 bar. The clouding point is affected enormously over pH 13.0 of the PAG quenchant and goes down to 43°C at pH 13.5. The high cooling rate of the PAG quenchant is obtained by the low clouding point quenchant. Therefore, the behavior of quench cracking in the pH 13.5 PAG sol. is similar to that of water. When SUJ 2 was quenched from austenitizing temperature 800°C, a considerable tensile stress existed on the surface area of all specimens, regardless of their pH values. A gel permiation chromatogram shows that the thermostability of PAG quenchant is excellent under sever conditions.

Puncher Tip Alloys for Aluminum Reduction Cells

Ore puncher tips operate in an extremely harsh environment in point-fed aluminum reduction cells and suffer rapid weight loss through corrosion attack when made from hot-rolled carbon steel bar. This study was undertaken to identify more durable materials for puncher tip fabrication.

Examination of surface defects induced during hot rolling of high-alloy steel bar and rod

The authors examine three problems associated with the production of high-alloy steel bar and rod by rolling in hand-operated mills. An outline is given of the mechanics of formation of surface defects and, by using a model material for hot steel (Plasticine) as well as three grades of steel, the defects were examined. Although the work was carried out using hand-operated mills, the conclusions drawn are relevant to commercial continuous mills for producing low-alloy and carbon steel rod and bar. The defects examined were cracking, split ends, and decarburization. The main conclusion is that careful selection of pass sequence, taking into account all the manufacturing and product requirements, is essential in order to control the rate of rejection of rod and bar with these defects

3-D finite element predictions of magnetostatic leakage fields

Traditionally electromagnetic leakage fields have largely been of interest to the designers of electrical machinery and magnetic tape heads. An increasingly important application of such leakage fields, however, relates to their use as a mechanism for the detection of defects in ferromagnetic materials. The finite element simulation of three-dimensional active leakage fields is described, and the theoretical predictions are compared with experimentally obtained leakage field profiles for a rectangular slot in a carbon steel bar. Particular emphasis is placed on techniques for determining boundary conditions and the appropriate excitation current distribution in the bar.

Crack Initiation and Propagation at Multiple Repeated Stress in Many Stress Levels

Many studies have hitherto been published on multiple repeated stress tests, most of which are based on the final fatigue fracture consideration. The research on the fatigue has mainly been made in consideration of the effect of repeated cycle stress based on the number of cycles and stress amplitude at final fracture. In this report the auther tries to take into account not only the failure point but also, and still more, the crack initiating point and the crack propagation process. This report is intended then to show the progress of fatigue in two separate steps, first up to the crack initiation period and then during the crack propagation period. The test has been made by means of a rotary bending fatigue testing machine, using as specimen a low carbon steel (0.17%C) bar with a V shaped notch.The results obtained are as follows in brief.(1) In the test of constant stress amplitude, the rate of crack propagation dλ/dN is low when the crack is initiated, then it shows a sudden increase after a certain depth of the crack is attained. This may be attributed to the stress concentration on the crack which begins to show crack-tip.(2) The effect of the repeated cycle stress prior to initiation of the crack on the width of the crack and the number of the crack initiating cycle seems to follow the linear damage law.

機械構造用炭素鋼の表面脱炭と疲労強さとの関係についての研究

The distribution of internal stress in the cross section of the decarburized carbon steel bars, which were normalized, quenched and tempered, or shot-peened, were measured.In this measurement of the internal stress, the dissolution method by acid solution was used in order to remove the outer layers of specimen without any effect of workhardening. The results obtained were as follows:(1) In the outer portion of both the normalized and the heat-treated specimens, containing the decarburized zone, the internal stress acts as tension. This tensile internal stress gets maximum at the surface layer and sharply decreases towards the center of the specimen, till it vanishes at a certain point, which lies at a depth of around 0.5-1.0mm from the surface, and afterwards changes its sign; this compressive internal stress increases towards the center.(2) As the depth decarburized increases, each of these maximum tensile internal stress decreases. The maximum value of this tensile stress is about 52kg/mm2 in the specimen, when the depth of decarburized layer is 0.15mm, and it reduces almost by half when the depth is 0.5mm. The compressive maximum internal stresses in their center zones are about 3-6kg/mm2.(3) The distribution of internal stress in the quenched and tempered steel bar after decarburizing is similer to that of the normalized one. The surface maximum tensile stress is 35kg/mm2 in the specimen having a depth decarburized of 0.15mm, and 15kg/mm2 when the depth is 0.5mm. Thus the maximum tensile stress decreases as the depth of decarburized layer increases.(4) The value of maximum tensile internal stress in the normalized steel bar at each depth decarburized is greater than those of the quenched and tempered bar.(5) The distribution of internal stress in the shot-peened specimen after decarburization is opposite to that of the above mentioned normalized, or heat treated steel bar.The value of maximum compressive internal stress at the surface layer increases as the depth decarburized increases. That is 32kg/mm2 in the specimen with a depth decarburized of 0.05mm and is 60kg/mm2 in the 0.5mm depth specimen.

加熱および冷却による炭素鋼棒の変形について(IV)帯状組織による変形

In this report the author made clear the influence of the banded structure of carbon steel bars on their dimensional changes due to heating and cooling and investigated its mechanism. When low carbon steel bars are heated and cooled, the transformations don’t proceed uniformly over the whole of a specimen, the α-phase and γ-phase are banded in parallel to the rolling direction, and the widths of bands of the two phases change relatively, so if the α-band yields, then the dimension decreases in the direction of the length of banded structure and increases in the transverse direction. When a eutectoid steel bar is heated and cooled, the A1 transformation does not proceed uniformly over the whole of a specimen, the pearlite and γ-phase are banded in parallel to the rolling direction. And the widths of the both bands change relatively, so if the γ-band yields, then the dimension increases in the rolling direction and decreases in the transverse direction. Dimensional changes of medium carbon steel bars due to heating and cooling diminish owing to the above contrary tendencies. In the case of hyper-eutectoid steel bars, the tendency of the above mentioned plastic deformation in the A1 transformation of the eutectoid steel bar is decreased by the existence of primary cementite.