Welded Steel Plates Research Articles

厚鋼板の電子ビーム溶接 Ｉ ビーム特性の炭素鋼板の溶接条件の選定

Relationship between welding conditions, bead shapes and occurrence of weld defects was investigated in flat, horizontal and vertical up position electron beam welding of heavy section carbon steel plates. As a result of these investigations, it was confirmed that sound full penetration welds could be made for carbon steels up to 150 mm thickness with proper beam oscillation.Main results obtained are as follows;(1) Beam shape at a beam current of above 160 mA is nearly parallel independently of focus coil currert.Beam diameter is given by the following equation;db=4.7×10-2(1/If)3.8Ib(mm), for Ib≤160 mA beam currentdb=1.4×10-2Ib+1.6(mm), for Ib>160 mA beam current(2) In flat position, penetration depth is given by the following experimental equation;hp=2.0⋅Ib/√ub (Ib/√ub>45)Occurrence of weld defects can be prevented by the application of beam oscillation which results in stabilized metal flow.(3) In horizontal position, penetration depth is given by the following equation;hp=2.9⋅Ib0.9/υb0.4 Sound full penetration welds can he obtained up to 150 tnm thick carbon steels without front support bars, when proper back beads are produced. It is observed that there is a marked beneficial effect of beam oscillation on prevention of weld defects.(4) In vertical up position, sound full penetration welds can be produced in carbon steels up to 75 mm thickness without front support moulds.

A simplified analysis of the residual longitudinal stresses and strains due to the gas-cutting and welding of thin steel plate

The paper describes a simplified analysis of the residual longitudinal stresses induced in a steel plate by a moving heat source of finite width. The effects of a point source are treated as a limiting case. A linear temperature distribution, identical at every cross section and subject to the condition of zero heat loss, is shown to be an adequate model for the purpose of the analysis. The relationship of the residual stresses to the linear heat input, to the width of heat source and to the stiffness of the plate is established. The particular results for a point source agree closely with more complex published work.

サブ・ゼロ溶接法について(第1報)

It is well known that in the case of welding high strength steel rapid cooling causes embrittlement and cold cracking in HAZ, on the other hand slow cooling causes softening in it. And the hgher the strength of steel, the more difficult it is to get enough notch toughness of weld metal as that of base metal. The purpose of this study is to weld high strength steel by austenitic steel electrode wire in order to get high weld-ing speed. And proof stress of austenitic weld metal is to be increased by refrigeration (sub-zero treatment) and aging after welding. As a rseult of the preliminary experiment by cast specimens, it was found theat the cast steel of composition of 17.5% chromium equivalent and 9% nickel equivalent will be increased in its strength and hardness by refrigeration and aging. And welded steel plate could locally be refrigerated by methylalcohol and dry ice mixture or by liquid nitrodgen.As results of sub-zero welding of HT-80 high strength steel, the following mechanical properties of weld metal were obtained after refrigration at -50°C;0.2% proof stress, 68kg/mm2tensile strength, 113kg/mm2elongation, 12%Charpy impact value, 2.8kg:-m/cm2 (at 0°C and -80°C)And the mechanical properties of weld metal refrigerated at -72°C and aged at 450°C for one hour were as follows;0.2% prooof stress, 100kg/mm2tensile strength, 126kg/mm2elongation, 15%Charpy impact value, 2.4kg-m/cm2 (at -80°C)

Evolution Structurale de L’Acier Maraging Soumis Ȥ des Cycles Thermiques Cumulȳs Ȥ Vitesse Rapide

This work involves with investigations on Maraging steel weldments done by GTA welding technique. Similar welding of maraging steel plates of 5 mm thick using ErNiCrMo-3 filler wire was done in order to evaluate the weldability and performance characteristics. Micro structural and X- Ray diffraction analysis were done to analyze the structure and phases developed post – weld. Block martensite was formed in the heat affected zones of the parent metal. Tension testing using different strain rates and hardness profile measurements were done to investigate the mechanical properties and the study concludes that the strain rate has considerable influence on the nature of ductility whereas it has very less influence on the Ultimate Strength of Maraging steel.

サブマージアーク溶接におけるひずみ挙動

As a basic research of strain characteristics in automatic arc welding process, which is executed in considerably higher arc current and welding speed than those of manual arc welding, the investigation has been experimentally carried out on submerged arc welding of mild steel plate under different heat inputs (Fig.1 and Table 2). Detailed observation covers the welding thermal cycles, the progress of longitudinal and transverse strains in base metal during welding and cooling as well as the distributions of the longitudinal total, elastic and plastic strains, the transverse shrinkage and the angular distortion after welding. Main results obtained are as follows.The transient mechanical strains of longitudinal and transverse directions occur respectively in tension and compression conversely to each other during the former stage of welding and, afterward, change into compression and tension according to the thermal expansion and shrinkage of the weld zone, which are inferable from the thermal cycles (Figs.3 and 8).From the distributions of longitudinal total strain and transverse shrinkage after welding, it is clear that the welded plate expands longitudinally in its middle and contracts in its outer portions, that is, the half of plate on either side of the weld line deforms into fan-shape, these rotational deformation being re-markable in case of large heat input (Figs.5 and 10). And also, the large heat input reduces the magnitudes of longitudinal plastic shrinkage occurring in the weld zone, extends transversely the region of its occurrence and consequently reduces the inherent shrinkage (Figs.11 and 12). The observed distributions of longi-tudinal residual stress and plastic strain along the transverse center line of welded plate, in case of low heat input, well agree with those theoretically derived (Tables 4 and 5).

局部定温加熱法による溶接割れ防止

Under the condition that the base metal to be welded is easily distorted, cracking seldom occurs. As to welding crack in high tensile steel plates, a lot of researchers have studied and presented the results of their studies, in which not a few researchers have done the restraint cracking test, such as U-type or slant Y-type.In this research, a restraint cracking test was done as follows, first of all, special butt welding of high tensile steel plates (Fig. 2) was made by manual arc welding process with coated electrode, NOW process or submerged arc welding process, secondly the profile of butt groove, which seemed to be most suitable, was chosen for each process, and thirdly for heating, "A Process for Local Heating at Constant Maximum Temperature with Gas Flames" published before was used. In these tests, the following investigations were made, such as prevention of welding crack at welded parts of high tensile steel and the relation between welding cracks and preheating or post heating.According to the results of experiments, the authors recognized the following facts:1. In case of butt welding of high tensile steel plates, Wel-Ten 80C, a crack rarely occurs. But if the. butt welding is made in central part of Fig. 2, crackings are likely to occur.2. In these tests, welding was done after preheating by the above mentioned process. There are instances where cloy preheating at 120°C could prevent cracking at the welded part. But when the temperature of preheating was 120°C and the interlayer temperature was kept at 200°C, in any method of welding, cracking was fully prevented.3. After welding by the various processes, post heating at 700°C was done by this heating method. By this post heating, the welded part with single-layer was softened and therefore cracking was prevented. But a small crack in crater was recognized in case of submerged arc welding process. Besides in case of multi-layer welding, if the interlayer temperature was kept at 200°C and post heating was done only after deposition of final weld, there was.no danger of cracking at all.

Mechanical properties behavior of neutron irradiated 12Ni-5Cr-3Mo maraging steel plate and companion weld metal

Charpy-V notch ductility and tensile properties changes in neutron irradiated 12Ni-5Cr-3Mo maraging steel have been evaluated following low (<250°F) and elevated temperature (550 to 740°F) exposure. The study was performed with 1-in, thick plate material (six heats) aged at 900°F for 2 and 20 hr to nominal yield strengths of 160 and 180 ksi respectively. Long term thermal stability of both heat treatment conditions was investigated for the conditions of irradiation. The <250°F and 550°F irradiation performance of matching (12-5-3) and mismatching (17Ni-2Co-3Mo) TIG weld deposits maraged to 180 ksi yield strength was also assessed in this study.General properties changes of the 12-5-3 maraging steel plate and companion weld metals were found to be rather small with <250°F exposures, indicating good resistance to neutron-induced embrittlement. However, a marked deterioration of notch ductility properties with long term exposure at elevated was revealed and traced to a non-nuclear thermal instability. The observed instability instability is believed to be a continuation of aging processes at temperatures well below the initial maraging temperature. Extended time-at-temperature treatments indicate that service above 550°F may produce sufficient properties changes for failure by low energy tear. Aging treatments of 1900 to 3300 hours duration increased the yield and tensile strengths of the 12-5-3 alloy by as much as 52.0 and 53.3 ksi respectively while not altering appreciably percent elongation and reduction of area values.

Welding of 0Kh23N28M3D3T heavy-gage steel plate

Welding of 0Kh23N28M3D3T heavy-gage steel plate

Application of entropy measurement technique in grey based Taguchi method for optimization of MIG welding process parameters

We seldom realized that without this form of metal work, many structures would cease to be in existence. A skilled journeymen welder joins metal in such a way that it is not able to be parted unless it is cut. Welding is an absolutely essential technique used in various industries like automotive industry, construction industry as well as in the aviation industry. Hence welding process parameters are required to be optimized for their responses or welding characteristics. This study incorporates entropy measurement technique based on grey Taguchi method to analyze multiple quality characteristic optimization of metal inert gas welding of low carbon steel plates. For this study, four control variables are selected current, voltage, gas flow rate and wire feed rate and analysing their effect on the four quality characteristics ultimate tensile strength, elongation %, bending strength and hardness of the weldments have been investigated in this paper. In order to optimize the multiple quality characteristic of the MIG welding, grey relational analysis coupled with entropy measurement method has been employed. Using entropy measurement method, value of weight corresponding to each quality characteristic has been assigned, so that the importance can be properly determined. Using the theory of grey relational analysis, these have been accumulated to calculate the overall grey relational grade. Signal to Noise ratio (S/N ratio) is applied to find the optimal parameter setting. To determine the contribution of MIG welding process parameters, Analysis of variance (ANOVA) on grey relational grade has been calculated. The confirmatory test also has been done for verifying the results. A foresaid methodology has been found fruitful in the cases where simultaneous optimization of huge number of responses is required.Keywords: Metal Inert Gas (MIG) Welding, Grey-Taguchi Method, Entropy Measurement Technique, Analysis of variance (ANOVA), S-N ratio.

チタニウムのプラズマ溶接

The plasma arc welding has a feature of giving deep penetrated weld bead, as reported on the welding of austenitic stainless steel plate. This feature is somewhat different from the conventional TIG arc welding.In the plasma arc welding of titanium plates (thickness 7-11 mm), sound welds are obtained with a careful shielding of weldments from the open air atmosphere. Metallurgical and mechanical tests are made with almost satisfactory results.From the view point of welding heat source, plasma arc has a property, resembles to linear heat source. Deformation and shrinkage of weldment by the plasma arc welding are thus far smaller than those by ordinary arc welding.These experimental results are described briefly in this article.

Measurement of Distribution of Brittle Transition Temperature in Welded Steel by Means of Hardness Test

This paper describes a non-destructive approach to measure the distribution of brittle transition temperature of welded steel plate by means of hardness measurement at low temperature. The transition temperature in this hardness test is defined as the intersections of two linear stages in the description of the logarithmic Vickers hardness versus the reciprocal of absolute temperature. The two intersections were found in the range between room temperature and -196°C. The higher one is called as the first discontinuity temperature and the lower is the second discontinuity temperature. Both the temperatures are plotted as a function of distance from the center of welding, and compared with the result by usual Charpy impact test. The hardness method has a special advantage for the case to change the properties in various ways in the narrow range as the heat affected zone by welding.The characteristics of the three stages in the temperature dependency of hardness are discussed from the observations of the deformations around the Vickers indentations by means of microscope and roughness meter.

ステンレス鋼のプラズマ溶接の研究

Recently, plasma process has been applied to such industrial uses as cutting and spraying. Arc plasma is constricted by the gas flow and/or metallic wall of nozzle in a plasma process. The temperature and the thermal energy intensity of the constricted arc plasma are much higher than those of ordinary open arc. In the cutting and welding applications, it will be expected that the plasma stream has a property of line heat source similar to the one as observed in Electrlon Beam Welding.In this report the experimental results on the plasma welding of stainless steel plate are described briefly. The electric capacity of plasma welding torch used in these experiments is about 8 KW. The plasma welding is capable of producing a narrow and deep weld bead by the action of "Key Hole". And a sound weld is obtained by one pass of torch even for a 15 mm thick plate. With the above welding energy source, optimum welding conditions are established for various thickness of plate. Welding speed in plasma process is much higher than that in TIG welding and others at the same welding energy.Various tests on the microstructure, mechanical property and the deformation of weld specimen are carried out with satisfactory results.It was confirmed that the formation of key hole in crater of bead had much influence upon the welding results. When the key hole is not formed, porosity is contained in most weld beads. The formation of key hole is sensitive to the travelling speed.

Penstocks and Scroll Cases for Niagara Power Project

Twenty-five generating units of 2190 Mw power project of Robert Moses Niagara Power Plant and Reservoir Pump Generating Plant are supplied by 25 steel plate penstocks and scroll cases with ID varying between 18 to 28 ft; steel plate erection, welding, and X-ray inspection are described; unconventional design and erection of 13 24-ft to 28-ft elbows; difficult welding of 1.812 in. thick steel plates.

A Proposal Concerning Propagation Test of Brittle Crack

As a testing method to obtain critical temperature-stress curve for propagation of brittle crack, the author proposes a notch tensile test of cross welded steel plate. An experiment has been carried out for the quenched and tempered steel “2 H”, having high notch toughness and high tensile strength, such as, 60 kg/mm2, and the test result was compared with those of ESSO test and of double tension test with each gradient and flat temperature distribution. The result obtained by the test was very similar to that of double tension test with flat temperature distribution. (cf. Fig. 7) The distinctive features of this test are summarized as follows : 1) The cross welded specimen, having a sharp notch in its high tensile residual stress field, may cause single stage complete fracture under lower applied stress than yield stress.2) When a brittle transverse weld metal is provided at the location of notch, running crack may propagate to the base metal at the temperature above critical temperature for crack propagation without gradient temperature destribution on the specimen. Therefore, it is easy to apply this test for the steel of excellent notch toughness.3) By adjusting the length of brittle transverse welded joint, sufficient speed of running crack may be obtained.4) Fracture stress level of the specimen may be adjustable by preloading at the temperature above critical temperature of crack initiation under low applied stress level.Further investigations should be performed about stress destributions at the propagation field under various loading conditions and also about stress re-destribution during crack propagation.

Effect of Notch Shape on Brittle Fracture Strength of Welded Steel Plate

The authors have investigated in their experiments the effects of residual stresses due to welding upon the initiation of brittle fracture in welded structures from the several points of view.As one of these series of their tests, an experiment was carried out to investigate the effect of notch shape, such as, length of notch and radius of notch root, on brittle fracture strength of welded steel plate, by conducting the notch tensile tests on wide longitudinal welded specimens and base metal specimens.The main results obtained are summarized as follows : 1) Providing the location of the notch root to the un-affected zone of base metal apart from the weld heat affected zone, wide longitudinal welded specimens caused brittle fracture under lower applied stress levels than yield stress at the temperature range below nil ductility transition temperature of the notch root, while the fracture strength of the base metal specimen, having same shape of notch, reached to high stress level as high as yield stress at the same low temperature range. (cf. Fig. 5 and Fig. 6) The exhaustion of ductility in steel at the root of notch is, of course, one of the reasons. why brittle fracture initiates as Mylonas pointed out. Although the exhaustion of ductility in steel may be a necessary condition for initiation of brittle fracture, it might not be a sufficient condition for low stress fracture, 2) In order to investigate the effect of notch length on brittle fracture in residual stress field, wide longitudinal specimens with different length of notch but constant radius of O. 1 mm were tested at the temperature of -30°C. Fracture test on the base metal was also conducted with different length of the notch. As the results seen from Fig. 9, the fracture strength of base metal decreases with the length of notch, while the fracture strength of welded specimens increases with the length of notch except the length below 36 mm. For the case of specimens with notch less than 36 mm the fracture strength increases as notch length decreases. This is mainly due to the higher initiation strength of weld metal. The reason why the fracture strength of welded specimens increases with the length of the notch is due to the reduction in residual stresses while the stress concentration factor at the root of the notch remains constant because of the same sharpness of the notch. This is a strong evidence of the effect of residual stress upon the initiation of brittle fracture.3) Effect of notch radius on the brittle fracture strength of welded joint was clearly confirmed as shown in Fig. 10. The radius of notch was varied from 0.1 mm to 1.0 mm for base metal and welded specimens respectively. If the radius of notch is greater than 0.3 mm, the reduction in fracture strength due to residual stress seems to diminish except extremly low test temperature. Therefore, it is concluded that the effect of residual stresses on brittle fracture can be evaluated only if the sharp notch exists in the residual stress field.

炭酸ガス関口線材アーク熔接法について(第8報)

As already described in the report 6, if the dried gases are supplied and the dried conduits are used with the rustless filler wire, a weld containing a very small content of hydrogen is obtained by the C.S. arc welding process.And it was recognized in the previous research on welding of mild steels that this precess gives the weld showing a higher ductility and strength. Accordingly, it is deduced that this process will be suitable for welding a high tensile steel.In this report, the authors clarified experimentally the composition of the filler wire, which gives the weld with the same or a more excellent mechanical properties as the base metal of a high tensile steel, Welten 55.That is, from the results of the mechanical tests of the joints and all weld metals obtained by this welding process, it was deduced that a filler wire possessing the carbon equivalent of 0.65-0.7% is necessary for a square butt welding of a high tensile steel plate, 9 mm in thickness, and one possessing a much more a carbon equivalent is necessary for the multi-pass welding of the steel plates with the thickness of 22 mm. The addition of titanium in the filler wire seems to be effective also for the increase of strength of weld metal.

自動熔接施工時に生ずる拘束亀裂について

It has been disturbing experience of those engaged in submarged arc welding of structural steel plates to find cracks in the weld metal. These cracks which frequently take place while the weld is still very hot, and usually while the joint is subjected to high stresses, are associated with weakness between dendrites and it is believed to be probably hot cracking caused by increasing restraint due to the larger thickness of plates.Using large restraint specimens authors have experimented of the development of these cracks quantitatively and compared the various welding procedures with the result obtained.Covering the experimental methods used and the results obtained, this paper presents data whose several phases are as follows :(1) In order to prevent the restrained crack, it is more desirable the deposit of the first layer is made larger. (cf Fig. 5, 6 and 7)Generally, speaking of the performance of joint after welded, a multi-layer weld is said better. However, in view of such fact, it seems to be somewhat dangerous to increase the number of layers too much, which may cause the dwindling of the deposit of the first layer.(2) Among two combinations of rod and flux used in test, the low manganese rod of the combination I whose width of bead is larger is showing much better result (cf Fig. 5, 6, 10 and 11) As for the restraint crack of manual welding, better fusion and higher the deposit top is showing a better result, but a different aspect is presented in the automatic welding.(3) In the restraint crack of manual welding, the cold crack mainly poses a problem, but in the automatic welding it is conceivable the crack develops at a fairly high temperature (cf Fig. 10, 11).

局所加熱による残留応力の除去について（続報）主として熔接材の簡易な残留応力除去法について

In the previous paper, the present authors showed that the residual stress restored in the cold worked specimen might be released by local heating. A similar treatment was applied to a welded steel plate and a satisfactory result was obtained. A low carbon steel plate (thickness=3 mm), electrically-welded was used as a specimen. The stress distribution in the specimen is shown in Fig. 1∼3, In the figure the individual parts to be heated are marked as a, b, c, AB, ect, the width of each part being 5∼10 mm. These parts were heated to 650° separately or at the same time. The results obtained are as follows: (1) When the part at which the distribution curve is very steep was heated, it was effective to release the stress as shown in Fig. 1. And when these parts were heated individually one after another, stress release was very remarkable, but if these parts or tensile stress area where heated at the same time, it was not effective at all. (2) If the temperature of heating was elevated to 1000° the effect was naturally far greater than that when lower temperature was applied.