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Volume 46, Issue 8
Displaying 1-17 of 17 articles from this issue
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Shizuo Mukae, Mitsuaki Katoh, Kazumasa Nishio, Kuniaki Kusaba1977 Volume 46 Issue 8 Pages 495-501
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESS5083 aluminum alloy plate of 10 mm thickness was welded by MIG pulse arc process. Then, impact test was performed on base and weld metal at room temperature, -75 and -196°C. For the weld metal, Charpy impact test was also performed on the weld metal after homogenization at 500°C for 20 hours.
Mg content dissolved in the weld metal was approximately the same near the fusion boundary as near the center of the weld metal and was 2.87 and 2.80%, respectively. On the other hand, the Mg content dissolved in the base metal was 4.45%. When the homogenizing was performed on the weld metal at 500°C for 2 hours, the dissolved Mg content increased to 4.10% and the content did not change after longer homogenized time.
Charpy impact values were approximately the same at -196°C as at the room temperature for the base metal. For the weld metal, however, the values at -196°C were lower than those at room tem-perature. This phenomenon was mainly due to the decrease of crack propagation energy. After the homogenization of the weld metal the Charpy impact values increased. Besides, crack initiation energy increased approximately linearly when the dissolved Mg content increased.
On the fracture surface of the weld metal dimple patterns were observed at room temperature and quasi-cleavage like structure was mainly observed at -196°C. After the homogenization of the weld metal, the dimple patterns were observed on considerably wider area of the fracture surface even at -196°CView full abstractDownload PDF (4012K) -
Observation of Growing Process of Penetration Depth Using Pulse Beam (Part 2)Hirosada Irie, Tatsuya Hashimoto, Michio Inagaki1977 Volume 46 Issue 8 Pages 501-508
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSWith the same electron beam welder as described in the report 1, rectangular pulse beams of various duration time were incidented on pure aluminum, aluminum alloy, copper, brass and mild steel under the nearly same other welding conditions and growing process of cavity or penetration depth was observed. The results are summerized as follows;
1) In all metals used, there is a cavity formed rapidly. This penetration speed depends largely upon energy density of electron beam.
2) The penetration depth in usual welding is decided not only by the drilling action but also by movement of metal.
3) Comparing among metals of the same matrix, the metal containing volatile elements shows more considerable drilling phenomenon than a pure metal. Whereas shape of the cavity in a pure metal corresponds to higher portion of electron beam energy distribution, that in its alloy corresponds to lower
4) Until a certain short welding time, weld penetration depth in rest metal is the same as that in moving metal. This is resulted from the fact that the diameter ofelectron beam is not infinitesimal and penetration speed of welding is much higher than welding speed so that all specimens are apparently rest until at that time.
5) Weld penetration depth hp in all metals except mild steel increases with respect to welding time τ approximately according to hp=C1τα(C1 and a are independent of τ, 0<α<1).View full abstractDownload PDF (552K) -
Calculation of Grain Size in Weld-Heat Affected Zone Using Heat Conduction EquationHiroshi Ikawa, Hiroaki Oshige, Shingo Noi, Koji Kanda1977 Volume 46 Issue 8 Pages 508-514
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn this report, calculation of grain size in weld-heat affected zone (HAZ) of two-dimensional bead was investigated combining grain growth equation during thermal cycle and heat conduction equation.
Main results obtained are as follows.
(1) Grain size in HAZ calculated using instantaneous plane heat source is nearly equal to that calculated using moving line heat source when welding speed is faster than about 12 cm/min.
(2) Grain size in HAZ can be calculated combining grain growth equation during thermal cycle and heat conduction equation assumed instantaneous plane heat source. Validity of this method was confirmed on TIG arc welding of commercial-purity nickel and TIG arc and submerged arc welding of steel.View full abstractDownload PDF (470K) -
Theoretical Consideration and Observation for Deep PenetrationYoshiaki Arata, Michio Tomie1977 Volume 46 Issue 8 Pages 514-521
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSSome theoretical discussions were performed for the penetration depth and an empirical formula was given for practical usage, which was certified to be correct for each output level up to 100 KW of high energy density beam.
A new type X-ray camera which detects the “beam hole X-ray” emitted from a beam hole was developed and it has more validity as the penetration became deeper. Using this method the deep penetration depth could be observed even during welding, besides after welding.View full abstractDownload PDF (2621K) -
Seishin Kirihara, Tsutomu Onuma, Kiyoshi Watanabe1977 Volume 46 Issue 8 Pages 522-527
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSWith the demand for the increasingly large capacity of machines and equipment, structural dimensions are growing large, and design stress is becoming higher eventually. This naturally necessitates the use of high-strength steel possessing high tensile and high toughness.
Although mild steel is generally adopted for welded structures, it needs an exceedingly large gauge to give sufficient strength and involves difficulties in building up welded structures. In this report on research, an examination was conducted on the effects of the intensity of restraint, restraint stress, and the thraot raito Qw upon delayed cracks during manual arc welding on high-strength steel.View full abstractDownload PDF (1459K) -
Precipitation Phenomenon of Carbides in Heat Affected ZoneHiroshi Ikawa, Yoshikuni Nakao, Kazutoshi Nishimoto, Shuhei Nakahama, ...1977 Volume 46 Issue 8 Pages 527-533
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSUp to this report, it was made clear that M23C6 precipitated at γ grain boundaries and δ ferrite in which M23C6 had precipitated, caused knife line attack phenomena in SUS 321 and SUS 347. In this report, the quantitative investigation on the precipitating behaviours of carbides in HAZ was carried out in, order to make clear the mechanism of knife line attack phenomenon in detail. Besides, the results obtained in this report were considered to be useful to confirm the mechanism of knife line attack phenomenon reported already.
The experimental results obtained in this report are as follows;
1) Precipitation curves of M23C6 in synthetic HAZ of SUS 321 and SUS 347 shift to lower temperature and longer ageing time side than that in SUS 304.
2) The quantities of M23C6 and MC type carbides in synthetic HAZ of SUS 321 and SUS 347 during sensitizing heat treatment from 550°C to 850°C were quantitatively examined.
3) It was made clear that M23C6 precipitated in all the knife line attacked region during sensitizing heat treatment from 550°C to 850°C. This fact strongly supports the mechanism which have been already reported.View full abstractDownload PDF (500K) -
Effects of Main Welding Conditions on Weld FormationToshio Yamamoto, Takio Okuda1977 Volume 46 Issue 8 Pages 534-541
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe influences of wedling current, welding speed and electrode force on the size and shape of the nugget and HAZ, indentation and weld formation process are studied using cold rolled mild steel having thickness of 1.2 mm. The results obtained are as follows.
Nugget width, penetration and indentation increase with the increase of welding current and the upper limit of welding current is restricted by the occurance of surface flash. As welding speed increases the rate of increase of penetration as against the increase of current becomes larger which restricts the upper limit of welding speed. Increased electrode force enlarges the weldable welding current range, especially under high speed condition. According to the observation of longitudinal sections, weld formation process can be divided into two types with welding speed. In case of an electrode force of 480 kg, the transition welding speed is about 4 m/min which coincides with the welding speed at which melting efficiency is saturated.View full abstractDownload PDF (5145K) -
Theoretical Analysis of Welding Conditions in Overlaying ProcessKimiyuki Nishiguchi, Takayoshi Ohji, Masao Furuta1977 Volume 46 Issue 8 Pages 541-547
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn this paper, welding conditions in overlaying process are discussed on the basis of heat conduction theory and surface tensional analysis of bead surface profile which was described in the previous papers.
In setting up welding parameters such as arc current and travelling speed, the following two conditions are of great importance. The first condition is concerned with the quantity of deposit metal corresponding to the required reinforcement and the second one is concerned with the heat input, ensuring the required melting width.
As for penetration shape, shallow one is required in this process. Hence, an important problem to be considered is associated with a property of distributed heat source. So, the property of typical distributed heat source is clarified, i.e., dimensions of penetration by the disk heat source and the line heat source of finite length are made clear and compared with those by the point heat source. Such a calculated heat input condition is correlated to the another necessary condition derived from the surface tensional analysis, where the wire meling rate is taken to be a reasonable value. Consequently, theoretical welding condition is obtained for each of heat source models.
As a result of these estimations, the available bead-width is limited in the overlaying by the point heat source model or the disk heat source model, where overlap bead is inevitable under the condition of wide bead. Accordingly, it may be concluded that one dimensional distributed heat source, such as submerged arc with strip electrode and high frequently weaving arc, is necessary for the overlaying process of wide bead.View full abstractDownload PDF (487K) -
Cutting with Constant Voltage WelderMasanobu Hamasaki, Fumikazu Tateiwa, Munehide Katumura, Yoji Ogawa1977 Volume 46 Issue 8 Pages 548-552
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe authers have previously described arc phenomena of underwater cutting using a consumable electrode water jet technique in freshwater at a depth of 0.3 m. In this experiment a MG type electric source with a constant voltage characteristic was used, and observing arc phenomena whilst cutting proceed, possibility was seen applying a electric source with an AC constant voltage characteristic. Thus with this electric source, cutting efficiency, polarity effect, arc moving and selection of cutting conditions were studies, and also as a result of cutting of mild steel and aluminum in fresh water at a depth of 60 m, the pressure of jetting water was not critical being 11 kg/cm2 and 8 kg/cm2 at 60 m deep to mild steel and aluminum respectivity and fast cutting speed with high quality was obtained, even though heightened secondary voltage was applied with increasing of a water depth.View full abstractDownload PDF (9023K) -
Kimiyuki Nishiguchi, Akira Matsunawa, Masaki Hori1977 Volume 46 Issue 8 Pages 553-560
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn this paper are described the arc behaviors, the electical and thermal properties and the wire melting characteristics in GTA and GMA in high pressure argon atmospheres up to 10 atm.
In a high pressure atmosphere, an arc shrinks much which brings the considerable increase in arc voltage. This increase is almost comes from the rise in potnetial gradient of an arc column and the increase in cathode potential fall is a little. In a hot cathode mode arc (GTA), the area of cathode root concentrates greatly in higher pressures, which eventually accompanies the acceleration of plasma stream. Therefore, the heat transfer to a mother plate is much dependent on the hot plasma jet. In a cold cathode mode arc (GMA), on the other hand, the distribution of cathode spots is much concentrated in high pressures, while the active area of current at electrode wire is kept constant. Therefore, the generation of plasma stream is suppressed. Concentration of cathode spots wandering region also brings the arc stabilization independent on the surface conditions of a metal. Hence, even the electrode negative GMA is more stabilized in higher pressures. Both the threshold current of metal transfer mode and the wire melting rate in spray condition decrease as the pressure is increased, because the electromagnetic detachment force becomes smaller due to the reduction of divergent angle of the arc current flowing pattern.View full abstractDownload PDF (4133K) -
Transverse CrackingKohiji Kishimoto, Hirosato Indow, Makoto Ebata, Masamichi Ohtomo1977 Volume 46 Issue 8 Pages 561-566
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIt has been well known that there often occur some kinds of hydrogen-induced cracking, such as transverse cracking and root cracking, in the submerged-arc welding of HT-80 steels. There have been many studies on them individually, but would be very few on all-round quantitative conditions to prevent them.
Therefore, as the first stage, the prevention of the transverse cracking has been dealt with here.
The conclusions obtained are as follows;
1) Experimental equations are proposed for preventing the transverse cracking as functions of Ceq of electrode wire or POM of weld metal, and diffusible hydrogen content and critical cooling time of weldment.
2) The residual stress may be ignored in the conditions for the prevention of the transverse cracking.
3) A new method for the transverse cracking test has been developed to conduct the experiment more easily.View full abstractDownload PDF (435K) -
Eiji Takahashi, Kenji Iwai1977 Volume 46 Issue 8 Pages 566-572
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIf the cold crackings occur in tack weld and remain in the weld grooves, the strength of the welded joint will decrease unexpectedly.
The initiation of this kind of weld crackings is known to be influenced by chemical composition of base plate, diffusible hydrogen concentration at the root of weld bead and the restraint intensity of weld joint. Therefore, it is very important to estimate the restraint intensity of tack weld joint from the view point of avoiding such weld crackings.
This research was performed for the purpose of studying the restraint intensity of tack wled joint and its effect on the weld crackings due to tack weld. The results are summarized as follows.
(1)The concept of the restraint intensity well predicts the condition of the crack initiation within such a small bead length that a heat source of welding can be regarded as an instantaneous one from the aspect of residual stress distribution produced in a tack weld bead.
(2)The correlation between the restraint intensity of the tack weld joint in real structures and various parameters influencing this value was obtained, and based on this relation a testing method for avoiding tack weld crackings in real structures was proposed.View full abstractDownload PDF (515K) -
Kunihiko Satoh, Masao Toyoda, Toshio Terasaki, Shoichiro Kaihara1977 Volume 46 Issue 8 Pages 572-577
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn the welded joint having a pre-existing defect, the crack tip is subjected to thermal stress/strain cycles by successive welding. Hot straining embrittlement and residual stress due to successive welding influence the brittle fracture initiation of weldment.
Thermo-elasto-plastic analyses by two-dimensional finite element method are carried out for obtaing thermal stresscut/straincut cycles during welding and distributions of residual stresses/strains near the tip of a pre-existing crack.
The results obtained in this report are summarized as follows:
(1) Residual stress/strain distributions near the tip of a pre-existing crack are cheifly determined by parameters.
(a) Maximum temperature at the crack tip TaM*=0.242α0 cut Q/cρhεY0
(b) Initial temperature θi*=αθi/εY0
(c) Temperature above which yield strength becomes zero θM*=α0θM /εY0
(2) Conventinal formulae are presented for the calculation of residual stress/strain distributions near the crack tip produced in single-Vee-groove weld.View full abstractDownload PDF (429K) -
Influence of Different Drooping Characteristics of Power Sources on Nugget FormationShuji Nakata, Masahiro Nishikawa, Takanori Suematsu, Takeyoshi Kaneda1977 Volume 46 Issue 8 Pages 578-585
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn order to investigate the influence of characteristics of the power sources on the nugget formation under the various conditions of weld current and the electrode force which control the collapse of projection, the power sources with no-load voltage V20 of 3.3V and of 6.3V were used in this experiment.
When the power source with V20=3.3V was used under low electrode force where the projection was scarcely collapsed, for the weld current above a suitable value, the tensile shear strength was stable with small amount of scatter and the welds failed in tear fracture in spite of occurrence of the initial splash during collapse of projection and the splash in the latter half weld time.
However, when the power source with V20=6.3V was used, the tensile shear strength was unstable with a large amount of scatter and the welds failed in the shear or the tear fracture at the rate about 50 % because of the initial intensive splash, so that the critical current could not be defined. Thus, the drooping characteristics with high no-load voltage were found to be able to supply the initial heat input into the projection part more than those with low no-load voltage.
However, under low electrode force the enlargement of the area of the current path due to the initial extensive splash decreased the current density and the heat efficiency, and after that these deep drooping characteristics were found to be unable to the following heat input enough to conpensate for this heat loss.
Under high electrode force where the projection was almost collapsed, the critical current was defined even if the power source with different no-load voltages were used. And the value of critical current in the case of using the power source with V20=6.3V was found to be 1000A smaller than that of the power source with V20=3.3V.View full abstractDownload PDF (3246K) -
Distribution of Anode of Cathode Spot within Cutting CrooveKimiyuki Nishiguchi, Kin-ichi Matsuyama1977 Volume 46 Issue 8 Pages 585-591
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn a plasma arc cutting, the wandering region of anode or cathode spot within a cutting groove was measured by the optical method, and the correlation between the spot wandering region and the cutting front shape was investigated.
The cutting front shape is characterized as shown in Fig. 3, and the anode or cathode spot mainly wanders in the BC region within the cutting groove. Then, the cutting front can be divided into three parts inspite of sorts of working gases and electrode polarities;
Region I; which takes upper part of the cutting front, and in which the cutting front is mainly melted by the heat flux from arc column.
Region II: which takes middle part of the front, and in which the most of anode or cathode spot exists and the cutting front melted by the anode or cathode energy in addition to the arc column energy.
Region III; which takes lower part of the front, and in which the cutting front is chiefly melted by the heat transfer from high temperature and high velocity plasma stream.
The spot wandering region II is essentially governed by the distance between torch axis and the center of cutting front, so that the region II shifts upwards and narrows according as cutting speed and/or working gas flow rate generally increase. At the reverse polarity in high flow rate of working gas (Ar), the region II, however, slightly expands toward downward according to increasing the gas flow rate, since the voltage to make a new cathode spot becomes to be neglected as mentioned in Report 1.
In nitrogen plasma arc cutting, peculiar anode spot motion is observed when the lower part of region III exists within the cutting groove. The peculiar anode spot slowly repeats the motion from lower part to upper part within the groove in period of about one second, and makes rough cut surface. Such a inconvenient spot motion is caused by the bigness of the ratio of distance between torch axis and center of cutting front against the cutting depth. So, the peculiar anode spot motion is resolved by using a working gas in which high percentage argon or oxygen are mixed into nitrogen, since the ratio is small in such conditions.View full abstractDownload PDF (6910K) -
Shogo Kanazawa, Kazunari Yamato, Tetsujiro Takeda1977 Volume 46 Issue 8 Pages 591-597
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIt was already shown that a reheat cracking was a grain boundary cracking occurring at high temperature and there were some relationships between the cracking susceptibility and a strength of HAZ at high temperature. But the strength of HAZ that is one of the factors influencing the susceptibility was not sufficient to explain the phenomenon thoroughly.
In this paper another factor was quantitatively examined. Experiments were made with a apparatus that could simulate a practical stress relief heat treatment using a small specimen. of weldment.
It was found out that the cracking susceptibilities of weldment could be expressed with two factors, the strength of HAZ and the stress relaxation characteristics of base material.
The results obtained from the experiments of the present paper are summarized as follows;
(1) Weldment which has high susceptibility to the cracking shows a little stress decrement during stress relief heat treatment and non-susceptible weldment shows a large stress decrement. The relaxation characteristics of weldment is mainly controlled with that of base material. Base material of a weldment that is more susceptible to the cracking shows a less stress decrement than that of a weldment that is less susceptible to the cracking. This characteristics of base material is another factor controlling the cracking susceptibility.
(2) The cracking susceptibility can be expressed with two factors in one figure, one is the stress relaxation characteristics of base material at high temperature and the other is the strength of HAZ at high temperature.View full abstractDownload PDF (3560K) -
Takuro Kobayashi, Takeshi Kuwana, Yasushi Kikuchi, Hidetoshi Furukawa1977 Volume 46 Issue 8 Pages 597-604
Published: August 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe Slag-Metal reactions in Electro-Slag remelting were studied by using several electrode wires and CaO-SiO2-CaF2 flux.
The following results were obtained;
(1) Manganese in the electrode wire is mainly oxidized after detachment of droplets from the electrode tips.
(2) Increasing SiO2 content in the flux, Manganese in the electrode is easily oxidized and Silicon content in the remelted metal increases.
(3) Equilibrium parameters (KW) in the slag-metal reactions are as follows;
a)(SiO2)+2[Mn]=[Si]+2(MnO)
KWSiO2-Mn=[%Si⋅(MnO)2]/(%SiO2)⋅[%Mn]2
logKWSiO2-Mn=-2.261(CaO/SiO2)+1.685
b)(SiO2)+2[Fe]=[Si]+2(FeO)
KWSiO2-Fe=[%Si](%FeO)2/(%SiO2)
logKWSiO2-Fe=-1.384(CaO/SiO2)+0.0055
c)[Mn]+(FcO)=(MnO)+[Fe]
KWMn-FeO=(%MnO)/[%Mn]⋅(%FeO)
KWMn-FeO=-3.467(CaO/SiO2)+6.314
d)(FcO)=[Fe]+[O]
LW0=[%O]/(%FeO)=0.0051View full abstractDownload PDF (495K)
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