All issues
Volume 42, Issue 3
Displaying 1-11 of 11 articles from this issue
- |<
- <
- 1
- >
- >|
-
Hydrogen absorption in arc meltingJun-ichiro Tsuboi, Shozaburo Nakano, Koki Sato1973 Volume 42 Issue 3 Pages 189-201
Published: March 25, 1973
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSAn investigation is made on the hydrogen absorption in a molten pool of weld metal.
JIS hydrogen test has been commonly used for the quantitative analysis of diffusible hydrogen content in weld metal. It is found that the estimation of hydrogen content in a molten pool from this method is incorrect due to the dependency of the results on test conditions.
The causes are;
1) It must take more than 5 sec after an arc off up to quenching a specimen in water.
2) The hydrogen diffused from deposited to the base metal during welding is accounted for the greater part of hydrogen collected by this method.
From these resaons the new technique is devloped, which can measure the hydrogen content in a molten metal immediately after an arc off.
A specimen is melted by a tungsten electrode in Ar-H2 mixture in a copper crucibles and tightly closed in it immediately after an arc off.
Hydrogen evolved from the specimen is laed to an oxidising furnace and accumlated in a cold trap as ice. The stored ice is determined by the volumetric analysis after its conversion to vapor.
The relation between hydrogen partial pressure in the arc atmosphere and absorbed hydrogen in a molten pool obeyed a law of square root within PH2<0.2 atm. in pure irons, low carbon steels, 1.7%Mn steels, 18-8 and 15-35 stainless steels. Hydrogen absorption in the arc melting, if it corrected using activity coefficients of C, Si, Mn, Ni and Cr on hydrogen, is nearly alike in every material and yield to Sievert's law in the temperature range of 2000-2200°C, taking into account the acivities and steel making data.View full abstractDownload PDF (805K) -
On the Heat-Tool WeldingHiroshi Kimura, Takuji Yamaguchi, Masakazu Tsubokawa1973 Volume 42 Issue 3 Pages 202-208
Published: March 25, 1973
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn the previous report, an experimental study of the molding property and ultrasonic weldability of fiber glass reniforced polyethylene was described. The present report explains the weldability of fiber glass reinforced polyethylene by heat-tool welding.
That is to say, as a new method of molding of fiber glass erinforced polyethylene (FRPE), we have made an impregnation sheet by combining glass fiber base material in the form of mat and resin made into a film beforehand. We wish to present here the properties and weldability of such impregnation sheet obtained through a series of experiments.
Fiber glass reinforced polyethylene has been made by impregnation sheet method with hot press, and possibility of welding by heating plate has been explored. In an experiment like this, it is essential that the glass fiber base material be satisfactorily impregnated with resin and that the adhesion between these two be strong. The impregnation sheet we have used in the experiments was 30% in the ratio of glass fiber content, registered approximately 5 times what of the tensile strength of the resin base mateial and showed comparatively good condition of impregnation in microscopic examination. Now, in welding of fiber glass reinforced polyethylene, it is necessary that the glass fiber diffuses mutually on both sides of welding part, and that the resin is deposited sufficiently and induces fully the glass fiber which has diffused mutaually.
It is interesting to note that fiber glass reinforced polyethylene has excellent physical properties and economic advantage of polyethylene, plus strength and heat resisting properties. However, the adhesive properties which are dependent upon polarity peculiar to polyethylene are controversial and this is why the industrialization of polyethylene has somewhat fallen behind. In this report, we have treated adhesive properties of a fiber glass reinforced polyethylene sheet itself, or, in other words, the weldability including a combination of glass fiber base material and resin. From this report, you may find that a composite material of polyethylene of higher strength can be obtained by the impregnation sheet method in which a glass fiber base material of mat form is combined with resin, and that the result of welding can be as excellent as the composite material itself.View full abstractDownload PDF (6215K) -
Isao Masumoto, Muneharu Kutsuna1973 Volume 42 Issue 3 Pages 209-217
Published: March 25, 1973
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIt 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/mm2
tensile strength, 113kg/mm2
elongation, 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/mm2
tensile strength, 126kg/mm2
elongation, 15%
Charpy impact value, 2.4kg-m/cm2 (at -80°C)View full abstractDownload PDF (5008K) -
Ken Sasabe, Isao Okane, Makoto Tanabe1973 Volume 42 Issue 3 Pages 218-224
Published: March 25, 1973
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe creep rupture test at 600°C of brazed joint of AISI 316 type austenitic stainless steel has been examined. The brazed joint was made with 21 Pd-48Ni-31 Mn filler metal under the heating conditions of 1, 180°C×2 min and cooling rate of 130°C/min in 5×10-4 Torr atomosphere.
From the test results, it is clear that the brazed joint used is difficult to apply in practice, because of the very scattered values of its rupture strength. This unstable test results are cused by microcracks in the dendrites occured at solidification of filler metal. Accordingly, an improvement of the brazed joint may expected by controlling the growth of dendrites. In this study, this control is carried out with the addition of a little titanium to the filler alloy used, for the prevention of the growth of dendrites in brazed metal.View full abstractDownload PDF (10907K) -
Effect of hydrogen on porosity formation in pure aluminum at non-arc meltingMasahiro Uda, Satoru Ohno1973 Volume 42 Issue 3 Pages 225-235
Published: March 25, 1973
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn practical welding of aluminum, there are many factors causing porosity in aluminum weld metal such as welding speed, arc voltage, arc current, and shielding gas composition.
This study has been done to establish the relationship between the solubility of hydrogen in molten aluminum and the formation of porosity under the given conditions of the temperature of molten aluminum and partial pressure of hydrogen.
The results are summarized as follows:
1) Pure aluminum was melted at various hydrogen partial pressures and temperatures by using the levitation melting apparatus, molten aluminum was allowed to fall into a specially designed copper mold, which gave the similar cooling rate as weld specimen. Porosity of this solidified specimen was checked by X-ray, section, and gravity inspections respectivly. Porosity concentration and its size increased with an increasing hydrogen partial pressure and temperature. Porosities were observed in the final solidification part, in the grain or at the edge of grain.
2) It was found that a driving force for the porosity formation in aluminum was strongly correlated with the solubility gap between the solubilities of hydrogen near the melting point (liquid state) and at an arbitrary temperature of molten aluminum. That is, when this solubility gap was large, many porosities were observed. For instance, porosities amounted to about 30% of the bulk of aluminum under the condition of 100% hydrogen and 1100°C, but no porosity was observed under the condition of 100% hydrogen and 700°C. From this fact, it is concluded that gas bubbles are not formed at solid-liquid interface but are already formed (corresponding to its solubility gap) in liquid aluminum under a rapid cooling condition.
3) Floating velocity of gas bubbles in liquid aluminum was calculated by assuming the size of gas bubbles. Form this calculation, it was found that the small size of gas bubbles had not given enough time for them to float out from the bulk to atmosphere under a rapid cooling condition.View full abstractDownload PDF (4635K) -
Kinsaku Nakane, Yoshimasa Torii1973 Volume 42 Issue 3 Pages 236-247
Published: March 25, 1973
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSUp to the present not a few sutdies on calculation of temperature distribution in resistance spot weld have been reported. In these studies, however, electrical contact area between two sheets being welded was not taken into consideration. Hence, their results of numerical calculation did not coincide with their experimental data.
In this study the authors derived the following formula for calculating the electric contact area under pressure by means of theory of elasticity, i.e.,
dc=de+kt
wherein dc is diameter of contact area; de, electrode diameter; t, plate thickness; k, constant. It is to be noted that the above formula does not contain the term of electrode force. However, the constant k is dependent on electrode force, hence, the formula might be said to involve electrode force term implicitly. The validity of the formula was confirmed by the results of photoeleastic experiment.
On the basis of the above finding and the experimental result that the contact area initially formed is kept practically unchanged during the entire process of welding, they derived the following formula for determining the optimum welding condititon for mild steel sheets of equal thickness, namely,
s=7.63×107 (de+0.8t)4/I2
wherein s is welding time (see); de, electrode diameter (cm); t, plate thickness (cm); I, welding current (A). The formula elucidates a useful relation between temperature rise in the contact zone and welding current.
This formula is proved to be correct by the welding experiments with the newly designed weld specimens.View full abstractDownload PDF (5430K) -
Kunihiko Satoh, Tsugio Fujimoto, Isamu Oda1973 Volume 42 Issue 3 Pages 248-258
Published: March 25, 1973
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe distributions of residual strain produced by spot heating are studied on an austenitic stainless steel plate. The relations between dimensions of plastic region and heat input are clarified experimentally to obtain the fundamental properties of welding deformation.
Various diameters of concentric circles are previously marked on the surface of specimens for measuring the strain (Fig.2). The specimens are spot heated at their center with different heat inputs by means of a TIG arc welding set. The thermal cycle of each specimen is observed at several locations, and then the specimen is cut into concentric rings to release the residual stresses. In this procedure the changes in diameter of marked circles due to heating and cutting are measured and the components of residual strain on the concentric circles in the plates are calculated.
The results obtained are as follows: The thermal cycle at any point of the plate can be presumed using the equation of heat conduction for instantaneous line heat source (Figs. 4, 5 and 6). The components of the total, elastic and plastic strains in circumferential and radial directions can be calculated from the changes in diameter of the concentric circle (Figs. 8 and 9). A plastic region is produced around the heated point and it causes residual tensile stresses, which are roughly equal to the proof stress of the material. The plastic region is extended in radius with an increase of heat input (Fig. 12). The observed maximum temperature at the boundary of plastic region is about 20 to 30°C, which is lower than the expected value. The measured results of residual stresses well agree with those derived in accordance with the inherent stress theory from the plastic strain distributions (Fig.10).View full abstractDownload PDF (741K) -
Takayoshi Shiraishi1973 Volume 42 Issue 3 Pages 259-267
Published: March 25, 1973
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSDownload PDF (720K) -
Shozaburo Ohta1973 Volume 42 Issue 3 Pages 267-277
Published: March 25, 1973
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSDownload PDF (669K) -
Takayoshi Ishiguro1973 Volume 42 Issue 3 Pages 277-282
Published: March 25, 1973
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSDownload PDF (1607K) -
Isao Yamaguchi1973 Volume 42 Issue 3 Pages 282-286
Published: March 25, 1973
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSDownload PDF (331K)
- |<
- <
- 1
- >
- >|