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Volume 40, Issue 9
Displaying 1-8 of 8 articles from this issue
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Akira Nakashima1971 Volume 40 Issue 9 Pages 850-860
Published: September 25, 1971
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSDownload PDF (2834K) -
Hiroshi Kimura, Masaki Imachi, Masakazu Tsubokawa1971 Volume 40 Issue 9 Pages 861-867
Published: September 25, 1971
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThis paper purports to inrestigate the effect of irradiation by Co-60 on the fundamental characteristics, weldability and adhesiveness of polyethylene.
High pressure polyethylene films, 0.07 mm in thickness, were used in this experiment and exposed to various irradiation doses up to 5×107r under various ambient conditions. Measurements of degree of crystallization, resolution rate in xylene, wettability and others were made. These materials were welded with heated tool or bonded by various adhesives and then experiments on boniing strength were performed.
The results are summarized as follows:
Decay of crystal and change of degree of crystallization about irradiated polyethylene were not recognized within the ilmits of this experiment. It can be concluded that the increase of cross linkings due to irradiation makes weldability lower and carbonyl groups whose existences have been confirmed by infrared spectra analysis imdrove adhesiveness.View full abstractDownload PDF (1684K) -
Toshiyasu Fukui, Yoshihiko Sugiyama1971 Volume 40 Issue 9 Pages 868-874
Published: September 25, 1971
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn this study, micro-fissuring in heat-affected-zone of aluminum alloy welds was investigated.
Test panels were 4, 6 and 12 mm thick plates of Al, Al-Cu, Al-Mg, Al-Mg-Si, Al-Zn-Mg-Cu and Al-Zn-Mg alloys. Micro-fissuring was detected by the dye-penetrant test and the observation of micro-structures of cross-section.
The results were as follows.
(1) Micro-fissuring in heat-affected-zone appeared to be lamellar tears, and it was the grain-boundary cracking showing a semi-continuous shape.
(2) Micro-fissuring was observed remarkably in Al-Cu and Al-Zn-Mg-Cu alloys, and followed by Al-Zn-Mg and Al-Mg alloys. It was scarcely observed in Al-Mg-Si alloy and .a commercially pure aluminum except for special cases.
(3) The external factors affecting micro-fissuring in heat-affected-zone were considered to be plate thickness, welding conditions and procedures, pass number and so on. The degree of micro-fissuring increased with the heat input per unit thickness of plate.
(4) On the other hand, the inherent factors were condisered tobe the thermal stress produced by thermal expansion and shrinkage and the partial melting of eutectic compositions in grain boundaries.
(5) It was concluded that the sequence and mechanism of lamellar tearing in heat-affected-zone were similar to those of the gene4ral soridification cracking.View full abstractDownload PDF (9666K) -
Kinji Tanuma, Tatsuya Hashimoto1971 Volume 40 Issue 9 Pages 875-884
Published: September 25, 1971
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe purposes of this study are to explain the effect of surface cleanliness on the solid phase weldability of metals, and to clarify the influences of welding factors such as temperature, pressure and duration on the mechanical strength of the welded joint In the experiment, the surfaces to be welded are polished by a wire brush made of stainless steel in the environment in the ranges 760-2×10-6 torr and then these metals are welded without melting under various welding conditions. The quality of the welded joint is evaluated by the tensile shear test at room temperature and the following results are obtained.
1. The wire-brushing in high vacuum is a very useful technique for the improvement of the weld quality, and that the surface cleanliness of metals to be welded is a principal factor for the solid phase welding in high vacuum.
2. The quality of welded joint is affected by the surface treatment and welding atmospheric pressure or the exposure to the environment befor welding, and these influences become more and more remarkable with a decreasing welding temperature.
3. The effects of the welding temperature and pressure on the mechanical strength of the solid phase weld made in high vacuum are noticeably greater than those of the welding duration.
4. In the solid phase welding at the temperature of the order of 35 percent of the absolute melting temperature of metal to be welded, the weldability of the metal is mainly affected by the reaction between the metal to be welded and the residual gases in vacuum chamber. Therefore, the solid phase weldability of the metal such as silver and copper which has much weaker affinity for gaseous oxygen is better than that of the metal such as magnesium, aluminum and titanium which has much stronger affinity for gaseous oxygen.View full abstractDownload PDF (6448K) -
Kunihiko Satoh, Masao Toyoda1971 Volume 40 Issue 9 Pages 885-900
Published: September 25, 1971
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn the welded joints, chemical composition and metallurgical structures of weld metal and heat-affected zone are different from those of base metal and change continuously in them. Mechanical properties in them will be also different from those in base metal. Mechanical behaviors of weldments will be different from those of homogeneous and isotropic materials. It will be important, therefore, to investigate the effect of the heterogeneity in mechanical properties on the mechanical behaviors of weldments.
In the present report, the welded joints are idealized as a model consisting solely of base metal and a soft interlayer as shown in Fig. 1. Such model specimens are made by flash butt-welding or narrowgap manual welding. Static tension tests of model specimens were made for several combinations of interlayer thickness and specimen diameter and several combinations in strength of base metal and soft interlayer. The quantitative evaluation of tensile strength is also made theoretically.
The results obtained are as follows.
(1) Static strength of welded joints including a soft interlayer depends upon the relative size of a soft interlayer, or the relative thickness X of interlayer thickness to specimen diameter for round bar specimens, and the relative thickness Xt of a soft interlayer to the plate thickness and the plate thickness to width ratio t0/W0 for plate specimens.
(2) The strength is elevated from that of a soft interlayer as the relative thickness (Xor Xt) decreases. When the ratio t0/W0 decreases from unity under a constant Xt-value, the strength rises to a certain definite value depending upon the Xt-value. The plate width W∞ above which the strength becomes almost the same as that of an infinite plate is roughly given by W∞=5t0(Xt≤1).
(3) The elevation of tensile strength is influenced by strength of the base metal as well as the value of X. Strength of welded joints increases predominantly for small values of X as the strength of the base metal is large. The tensile strength of welded joints is evaluated quantitatively by the authors' theoretical analysis and the experimental equations.
(4) Ductility of the welded joints depends upon the value of X and the ratio κ of tensile strength of base metal to that of soft metal. The ductility decreases with decrease of X up to a certain minimum value, after which it increases in the opposite direction. The minimum value becomes smaller as the κ-value increases.View full abstractDownload PDF (4169K) -
On the roughness of base metal prepared by machiningIchiro Kawakatsu, Yoshifumi Suezawa1971 Volume 40 Issue 9 Pages 901-909
Published: September 25, 1971
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSUsually, most of brazing parts are produced by machining or other mechanical process at the massproductive factories. These brazing parts are brazed in their shape without refinishing by other process. This paper presents some experimental evidence that the roughness of base metal surface machined by mechanical process affects the butt joint strength of mild steel brazed with B//-8 filler metal. To obtain some experimental data on the effects of surface preparations, specimens of mild steel (SS41 13×75) were prepared. The two abutted surface of each specimen were identidally finished by the following processes :
(1) Machining by plain milling cutter
(2) Grinding by 60# grinding wheel
(3) Grinding by 80# grinding wheel
(4) Electrolytic polishing
(5) Super finishing by 240# grinding stone
Among these specimens, the roughness of base metal machined by milling cutter was high, and others were lower as shown in Fig. 1. The brazing operation of these specimens was carried out using a 35 KW resistance furnace operating in hydrogen atmosphere. Tensile test of these specimens gave the results as follows :
(1) Tensile strength of specimens machined by milling cutter was very high, its va.lue being 45.12 kg/mm2. But the strengths of specimens ground by 60# 80# grindibg wheel and other process were lower, these value being 3738 kg/mm2
(2) These results indicated that the tensile strengths of high roughness specimens were higher than that of low roughness specimens.
(3) Most of specimens were failured at filler metal zone as shown in Photo. 2, but a few of them were failured in the base metal.
Also, studies on spreadability of filler metal on the base metal machined by mechanical process were conducted. As a result, some typical phenomena are shown in Photo 1 and Table 2. In general, spreadability of filler metal on the base metal machined by milling cutter was excellent and those of other specimens were lower.View full abstractDownload PDF (7340K) -
Characteristics of Solidification Structure in High Purity Aluminum Weld MetalTomio Senda, F. Matsuda, M. Kato, H. Nakagawa1971 Volume 40 Issue 9 Pages 910-916
Published: September 25, 1971
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe growth direction of cellular subgrains and the preferred orientation in columnar zone in TIG-arc weld metal have been investigated for aluminum 1 mm thick sheets of 99.96% purity. Conclusions obtained are as follows:
(1) The growth direction of cellular subgrains in the weld metal of such a high purity aluminum agrees with the direction of the maximum temperature gradient at the solid-liquid interface, and is independent of ‹100› direction. Therefore, when the direction of the maximum temperature gradient gradually changes as growth proceeds, the growth direction follows its change.
(2) A competitive growth among the columnar crystals proceeds near the weld center. As a result, the columnar zone near the weld.center has [100] fiber texture.View full abstractDownload PDF (7383K) -
In Case of Gas Shielded Arc WeldingNoboru Kimata, Seiichi Ando1971 Volume 40 Issue 9 Pages 917-928
Published: September 25, 1971
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn 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.View full abstractDownload PDF (5666K)
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