Manual Arc Welding Research Articles

Improving the weldability of steel 28G2SFB

1. To ensure satisfactory weldability of casing pipe of strength group E the carbon content of steel 28G2SFB should be 0.23–0.27%. In this case the heat-affected zone retains a value of αp ≥ 1.5 kg-m/cm2 at room temperature with a cooling rate of 10–30 deg/sec after welding, which corresponds to manual arc welding of steel 8 mm thick at a linear energy of 2200–3200 kcal/cm. 2. The weldability of the steel is highest with 0.15% C. However, at this carbon concentration the value of σ0.2 may be 50 kg/mm2 for steel 28G2SFB, i.e., a level corresponding to strength group K.

厚板６０ｋｇ／ｍｍ?Q２?R高張力鋼溶接部のぜい性破壊発生特性 Ｉ 切欠角変形付広幅引張試験による検討

Brittle fracture initiation characteristics of manual arc and submerged arc welded joints of 60 kg/mm2 high strength thick steel plates were investigated by testing wide plate tension specimen with angular distortion and with a surface notch. The test results were analized by fracture mechanics. The results are summarized as follows.:(1) The lowest V-charpy impact toughness in the weld zone was obtained at the weld fusion line.(2) At temperatures above 0°C, the fracture initiation stress obtained from the wide plate specimens was not so lower than the yield strength of the steel.At lower temperatures, however, the fracture initiation stress was greatly lowered. The decrease was particularly remarkable below -10°C in transversely welded W(1) joints and below -5°C in T-type welded W(1)+W(2) joints and also repair welded joints with some residual stress.(3) The fracture toughness was calculated quantitatively from the fracture initiation stress. The values calculated in the transversely welded W(1) joints, the T-type welded joints and the repair welded joints decrease in a single band as a function of temperature.(4) The fracture toughness in the weld fusion line of the welded joints for 60 kg/mm2 high strength thick steel is high value above 0°C, but it is remakably lowered in the temperature range of -5-20°C and shows larger dependency on temperature than that for, 80 kg/mm2 high strength thick steel. And this steel does not show the embrittlement by stress relief annealing. Therefore, there is little difference in frecture toughness between as-welded spcimen, stress relieved specimen and repair welded specimen.(5) The fracture toughness values of the manual arc welded metal and of the submerged arc weld fusion line are almost equal to that of the manual arc weld fusion line.

Low Cycle Reversed Bending Fatigue Curves of 9% Ni Steel and Weld Metal

Deflection controlled reversed bending fatigue tests in low cycle fatigue range were carried out at ambient temperature and at-196°C on five 9% Ni steels of ASTM A553 grade A and transverse butt joint specimens made by MIG arc welding and manual arc welding. In addition, notch effects were investigated by introducing a surface notch of the elastic stress concentration factor of approximately 3 into the test section of both base and weld metals. Cyclic amplitude of surface strain at the test section, which was continuously measured by a plastic-range type strain 'gauge at ambient temperature and-196°C, showed a stationary behaviour after a number of imposed cycles corresponding to a few percent of crack initiation life. This stationary strain amplitude ea is used for the evaluation of low cycle fatigue strength which is plotted against number of cycles to crack initiation Nc. In case where measurement of surface strain amplitude failed, this was estimated from a dynamic calibration curve of ea versus bending deflection.The relation between ea and Nc was expressed by a modified Stromeyer's formula, providing any given percent probability curve for crack initiation basis. Notch effects are observed at room and low temperatures by showing approximately 1. 7 of fatigue strength reduction factor, while weld metals are insensitive to the effects. Fatigue strength is generally higher at-196 °C than at ambient temperature. Weld metal shows lower fatigue strength than base metal in the whole life range.

Electrodes for manual arc welding of corrosion resistant nickel-chromium-molybdenum alloys

Electrodes for manual arc welding of corrosion resistant nickel-chromium-molybdenum alloys

極厚 H 形鋼を用いた鋼構造柱はり接合部の力学的性状に関する実験的研究

The statical characteristics of beam-to-column connections of heavy steel section members at lateral loading are experimentally investigated. The variable factors of this experiment were the size of section, the combination of beam and column members (beam flange thickness : 40.60mm, column flange thickness : 75, 90, 125mm) and the welding method of beam flange to column flange (manual arc weld and simplified electroslag welding), so that eventually six specimens were used. Brittle fracture was observed at the beam-to-column connection under room temperature in four specimens at ultimate stage of loading. In one specimen the brittle fracture tookplace at the center of the panel zone (the crossing area of beam and column members) in the principal stress direction, and in the other three spcimens it occured at thd butt weld of beam flange to column flange. Those brittle fracture took place at 1.06〜1.21 times of the full plastic strength of beam members. This kind of phenomenon was also reported another previous paper. Therefore it is concluded that the brittle fracture at the beam-to-column connection may take place very often at high stress level under lateral loading, when heavy steel section members are used. The relation between the yield strength of the panel zone and that of beam member and the effect of reinforcement of the panel zone by doubler plate were also investigated.

The Short Term Effects on Health of Manual Arc Welding

The Short Term Effects on Health of Manual Arc Welding

Reduction of Costs in Manual Arc Welding

Reduction of Costs in Manual Arc Welding

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).

高マンガン鋼と高炭素鋼との溶接(第2報)

In report 1, the manual arc welding of austenitic manganese steel to high carbon steel was studied, the main characteristic of which was to butter, before joining, the groove face of high carbon steel with austenitic covered electrode.This paper describes the results of some experiments on welding of the above two dissimilar metals by gas shielded arc welding process.To select appropriate welding wire and welding conditions for buttering, single bead weld test and FISCO cracking test were made using high carbon steel as base metal, five austenitic welding wire as electrode, and CO2, CO2-A, A or N2 as shielding gas.16 Mn-16 Cr and 25 Cr-20 Ni welding wire are available for buttering electrode and CO2-A for shielding gas from the viewpoints of weld metal hardness, microstructure, weld defects and crack susceptibility of weld metal.Carbon steel rail and austenitic manganese steel rail (50 PS type) were then welded together automatically by gas shielded arc welding process: The groove face of the former was buttered vertically with above-mentioned wires and shielding gas and rail welding apparatus, which could be used not only for rail joining by welding but also for buttering with some modifications. An austenitic manganese steel rail was welded to the buttered carbon steel rail with I-groove and almost the same welding conditions as in the case of gas shielded arc welding of austenitic manganese steel rails investigated previously by the authors. The values of maximum load and deflection in bending tests of welded rails were 75-85 t and 56-84 mm with head-up (span 1 m, load applied at mid span) and they are almost equal to the welds by manual arc welding with V-or I-groove joint.Welding takes about 11 minutes for buttering and 7.5 minutes for joining.

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.

高マンガン鋼と高炭素鋼との溶接(第1報)

The welding of austenitic manganese steel to high carbon steel has been thought to be very difficult due to the difference of their metallurgical properties and others. The authors paid special attention to the procdeure to join them by manual arc welding after buttering the groove face of carbon steel. Various fundamental experiments were performed to select proper electrodes for buttering and joining, and welding conditions, though mention here is given mainly of the buttering electrode selection tests- 1) Hardness test and microscopic inspection of weld metal, 2) Angle-expanding type cracking test of weld metal and, 3) Impact test of weld zone.Based on the results obtained, austenitic manganese steel rail and carbon steel rail (high carbon steel) were welded together, and the welded rails were subjected to bending test, drop-weight test and so forth. The results show that considerably reliable welds are obtained if they are welded together by the following methods: 1) Austenitic manganese steel which has good weldability and no casting defects is used. 2) The welding groove is finished to V or X and arc welding process is executed in flat position. 3) The vicinity of the groove of carbon steel is preheated to 300-400°C, then two layers with 25Cr-2ONi or 25Cr-12Ni type electrodes or one more layer with 16Mn-16Cr type electrodes are buttered over the groove face. 4) The manganese steel rail and the buttered carbon steel rail are welded together with 16Mn-16Cr electrodes. Craters are peened after each pass followed by forcible cooling of the weld zone. 5) The impurities contained such as phosphorus should be as low as possible in the electrodes and the electrodes should give weld metals of very low crack susceptibility. 6) The postheating which is usually adopted for the welding of high carbon steel is not performed.The final object of this study is to establish the prodceure to weld austenitic manganes steel crossing to carbon steel rail and the welds are now under field test.

極厚鋼部材の脆性破壊

When pull plate (i.e. flange of beam)-plate thickness is 22mm. or 28mm.-welded into wide flange section member (i. e. Column)-its flange thickness is 40mm., 50mm., or 60mm. and web thickness 25mm., 50mm., or 40mm.-by Simplified Electroslag Welding using cored wire or manual arc welding and bended the latter by pulling the former (see, Fig.-1), brittle fracture was occurred in wide flange section member at and above its full plastic load at room temperature (see, photo.5). In this case, the ratio of the maximum deflection to the elastic limit deflection is 1.5〜8.8 (see, Table 7). Also brittle fracture of wide flange section member was occurred at room temperature in Case of X-type tests (see, Fig.-2). This phenomenon of heavy steel section is very important in design of structure of multi-storey buildings, and so these results are reported in detail in this paper with the results of supplemental tests and material tests (see, Table 1 and Fig.-3〜Fig.-7), and are analyzed qualitatively.

高マンガン鋼のガスシールドアーク溶接(第3報)

A prototype gas shielded arc welding apparatus for continuous automatic welding of austenitic manganese steel rail was built. This apparatus consists of the main assembly including abed, copper blocks and a torch-moving mechanism, the special torch, the controller for controlling the torch movement, the operating panel and the ordinary gas shielded arc welder. It is provided with a device for water-cooling the heat affected zone (HAZ) of base metal.Using the above-mentioned apparatus, austenitic manganese steel rails were welded by gas shielded arc welding process. The materials and welding conditions adopted are as follows: Base metal; 50 kg/m PS type, Wire; 16 Mn-16 Cr, Dia.; 1.6 mm, Shielding gas; CO2-A (50-50%), Joint type; I-groove, Gap; about 16 mm, Arc voltage; 35V, Current; 475A (average), Procedure; automatic and continuous, Forced cooling of base metal; HAZ water-coiled during welding, the whole weld water-cooled after welding.The bending test results on welded rails show that the values of maximum load and deflection are fairly good-76-83 t and 61-103 mm with head up and 73-77 t and 71-77 mm with head down respectively (span 1 m, load applied at midspan). Fracture invariably propagates through the HAZ within 15 mm of fusion line. In certain areas of HAZ, the impact values. are considerably inferior to those of base metal, but except in the cases where casting defects are present, they exceed 10 kg-m/cm2 (2U, 20°C), with considerable toughness retained.Weld metal is almost free from such welding defects as cracks or blow-holes. Local high-temperature cracks may be observed in the HAZ.Presence of such cracks seems to be practically harmless in general use but they should be minimized in welded rail joint.Welding takes about 6 minutes, which is by far shorter than 4.5 hours needed for manual arc welding of Vee-groove joint.

Bead cracking control in manual arc welding of annular seams in high-strength joints

Bead cracking control in manual arc welding of annular seams in high-strength joints

Manual electric arc welding of double-layer St. 3 + 0Kh23N28M3D3T steel

Manual electric arc welding of double-layer St. 3 + 0Kh23N28M3D3T steel

被覆アーク溶接ならびにサブマージアーク溶接における冷却過程について

Cooling time, which has an immediate connection with root cracking in a high strength steel weld with its strength level of 60 kg/mm2 and below, from 800 to 300°C was measured for various welding conditions in the cases of welding with coated electrodes and submerged are welding, respectively. Experimental formulas for the estimation of the cooling time were obtained and these nomographs were shown.The main conclusions are summarized as follows:(1) Dimensions of heat flow in a weld were varied by any particular combination of welding condition, plate thickness and the shape of penetration.For the cooling process with two-or three-dimensional heat conduction in a weld, a relation between temperature T on a weld and cooling rate (dT/dS) as the temperature T is shown as follows :(dT/ds)T∞(T-T0)nwhere T0: initial temperature of platen: the exponent which is varied with dimensions of heat flow in a weldHence, the dimensions of heat flow was clearly shown as the gradient of a line in a logarithmic groph of (dT/dS) VS. (-T-T0).(2) In a finite plate, it was able to determine a minimum size of specimen, which is equivalent to an infinite plate for the given weld heat input, according to the temperature range of a weld thermal cycle to be considered. When they consider the cooling process to 500 and 300°C, the Value of T in the following formula should be chosen as, T*≤320 for 500°C and T*≤210 for. 300°C, respectively.Where T*=0.24ηJl/mc+T0(°C)η: thermal efficiency of arc, j: heat input (Joule/cm)l: bead length (cm), m: weight of plate (gr) andc: specific heat (Cal/gr.°C)(3) If thickness (t), initial temperature (T0) of plates and weld heat imput (J) are given in the case of single bead-welding, cooling time (s) from 800 to 300°C at manual arc welding and submerged arc welding can be estimated with the following experimental formula or nomographs by the present authors;S=K·Jn/(40-T0)2{1+2/πtan-1(t-t0/a)}

CO<SUB>2</SUB>-O<SUB>2</SUB>アーク溶接における溶接条件について(第2報)

Using a constant potential type rectifier, many beads were deposited on plates by CO2-O2 arc welding, varying polarity, open voltage and feeding rate. And the deposition efficiency were measured. For the purpose of comparison, the same experiments were carried out with argon arc and manual arc welding with a coated electrode.The experimental results are as follows :1. At a constant feeding rate, the deoposition efficiency increased with the increment of open voltage.2. At a constant open voltage, the deposition efficiency increased with the decrease of arc voltage and the increment of welding current.3. In the case of CO2-O2 arc welding the deposition efficiency reaches 99% under an optimum condition.4. The deposition efficiency with the straight polarity is not so good as with the reverse polarity. With straight polarity, the maximum efficiency did not over 90%.5. Argon arc welding showed the same tendency as the CO2-O2 arc welding.6. In the case of the manual arc welding with a coated electrode, the maximum deposition efficiency was 88%.

軟鋼溶着金属の切欠靱性におよぼす合金元素の影響(第7報)

In ordinary manual arc welding, the weld metals was obtained by successive addition of graphite from lime-fluorides type flux. The effect of carbon on Charpy V-noth properties was determined on the weld metals thus obtained.Carbon fines ferrite grain size of weld metals, reduces maximum energy rapidly, increases transition temperature at a rate of 15°C per 0.1%, and widens transition range regularly.

ガス被包金属アーク溶接による鋼材溶接部の気孔生成について(第2報)

In the same way as the previous report, many beads were deposited on plates by CO2-H2 and A-H2 arc welding, varying the volume percentage of mixed hydrogen in supplied gas.Experimental results made clear the following facts :1. In the case of CO2-H2 arc welding, the weld metal becomes very porous, when the volume percentage of hydrogen in supplied gas is over about 10%.2. It is deduced from this value that the weld metals obtained by CO2-O2 arc, argon-arc, submerged arc welding or manual arc welding with a low-hydrogen lime type electrode hardly become porous on account of hydrogen only, but the weld metals with a ilmenite, cellulose or high titania type electrode may become porous by hydrogen only under certain unfavorable welding condition.3. The rust of joint may produce hydrogen porosity of weld metal.4. In the case of A-H2 arc welding, the weld metal becomes porous at the lower volume percentage of hydrogen than in the case of CO2-H2 arc welding.

Al鋼の熔接に関する研究

Al-steel, which has a high heat-resistance property, is welded by the general coated electrode and Ni-Cr type electrode with manual arc welding method or by the swaged wire electrode from the same component plate with tungsten innert gas arc welding method, submerged welding method and bare electrode D.C manual arc welding method.The results of mechanical test for weldment by each methods show that the elongation at room te-mperature is very low as compared with base metal, and it is not recovery by the post heat treatment at 700-900°C.According to the measureing results of scale rate for the elevated heat in the range 150-950°C during 3 monts, that of the deposit metals welded by the swaged wire electrodes are in the range 4.9-8.2 %, that by the Ni-Cr type electrodes are 9.3-17.6% and that by the general coated electrodes are 27.5-38.7%.To conclude the examination results of appearences of weldment, X-ray photo-graphy, hardness test and microstructures, tungesten innert gas arc welding method used the swaged wire electrode obtains the best weld joints.