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Volume 20, Issue 9
Displaying 1-6 of 6 articles from this issue
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Shigenori HORI, Norio FURUSHIRO, Testuya SUGANUMA1970 Volume 20 Issue 9 Pages 429-434
Published: September 30, 1970
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSMeasurements of deformation and internal friction and optical microscopic observation were made on commercial pure aluminum specimens when they were under various uniaxially repeated tensile loads.
The uniaxially repeated tensile load was cyclically given by a loading machine with an eccentric cam. It was given by pulling the spring to the stroke of 10mm and various loads were given by the exchange of the spring.
The relation between amplitude and repeated number to rupture was nearly identical with the S-N relation in ordinary push-pull fatigue test. Two types of rupture were observed under the uniaxial repeated tensile stress conditions. One was a ductile rupture which gave a large local contraction, but the other would be a fatigue rupture which did not give a so large local contraction. The former ductile rupture occurred under the conditions of higher stress and its total elongation attained to about 5060%. Whereas, the latter fatigue rupture occurred under the conditions of lower stress and its total elongation attained to about 20%. Slip band striations were sharpl yproduced under lower stress conditions and clear caterpillar patterns to be characterized by fatigue rupture also appeared on the fracture. They were much different from those produced in the structure under the conditions of higher stress or tensile test.
The change in amplitude-independent internal friction with total plastic strain under various stress conditions was plainly increased with the increase of total plastic strain.View full abstractDownload PDF (1422K) -
Studies on chill cast Al-Zr alloys (2nd report)Riei ICHIKAWA, Teruo OHASHI1970 Volume 20 Issue 9 Pages 435-442
Published: September 30, 1970
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSIt was reported in a previous paper that supersaturated solid solutions containing up to 1.2% of zirconium in aluminum was obtained by quenching of molten alloys and a remarkable hardening was found after ageing the alloy at 400°C. This paper reports the effects of the third additional elements such as copper, magnesium, manganese, silicon and zinc on the age hardening of Al-1%Zr alloy. The effects were investigated on the wedgeshaped specimens obtained by rapid solidification.
The results obtained were as follows:
(1) The supersaturated solid solutions containing Zr were found in the thinner part of the wedge-shaped specimens which had been rapidly solidified. The range of thickness of specimens for forming such a structure depended upon the kind and quantity of the third additional elements.
(2) Remarkable age hardening was found in the part of the supersaturated structure of the binary Al-1%Zr alloys by ageing at 400°C for 1 hr. The effects of the third elements on the age hardening were arranged in ascending order as follows: Zn<Mg<Cu<Mn (in which the effect of Zn was nearly in the same order as the binary alloy containing no third elements)
(3) The alloy containing Si of up to 2% showed remarkable age hardening, but when Si content was more than 2%, the hardening turned to be less.View full abstractDownload PDF (1815K) -
Shigeo ZAIMA, Tadao OKAZAKI1970 Volume 20 Issue 9 Pages 443-447
Published: September 30, 1970
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSExperiments were conducted on orthogonal low speed cutting of aluminum alloys to discuss the effects of cutting conditions such as tool dimensions (rake angle, clearance angle, radius of curvature at tool tip, roughness of rake surface, etc.), depth of cut and cutting speed on roughness of machined surface with respect to plastic flow of the material near the tool tip.
The results obtained were summarized as follows:
(1) It was found that roughness of machined surface was improved under the conditions of releasing chip flow; for example, increase of rake angle or smooth finishing of rake face.
(2) The clearance angle seemed to have no great effect on chip flow, but its increase had effect on the decrease of burnishing, by which the roughness of machined surface was slightly improved.
(3) The increase in radius of curvature at the tool tip released the chip flow when the chip thickness was small, and brought about the improvement in roughness of machined surface; however, these effect were varied according to the depth of cut.
(4) When the compressibility of chips was gradually increased with the increase in depth of cut or cutting speed, the speed of chip flow was decreased, which brought about the lowering in roughness of machined surface.View full abstractDownload PDF (1351K) -
Basic studies on solidification mode of welds (1st report)Toshiyasu FUKUI, Keizo NAMBA1970 Volume 20 Issue 9 Pages 448-457
Published: September 30, 1970
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThese studies were made on the morphology of solidified structures in aluminum alloy welds. Experiments were conducted to investigate the effects of heat inputs on grain-structures, dendrite cell size, distributions of solutes and other behaviors of 99.5%Al, Al-4.5%Mg and Al-4%Zn-2%Mg alloy welds.
Grain-structures grew slightly with the increase of heat input per unit length, though columnar grains were likely to be formed on the side of low heat input and granular grains were on the side of high heat input.
In Al-4.5%Mg and Al-4%Zn-2%Mg alloy welds, feathery grains were observed.
In 99.5%Al, Al-4.5%Mg and Al-4%Zn-2%Mg alloy welds, there were observed layer lines or solute bands which corresponded to grain-refined region as well as to alternate region of fine and coarse dendrite cells.
If three dimensional heat flow during solidification was approximately ensured, the dendrite cell size increased parabolically with the heat input per unit length as predicted from the theory of dendritic solidification involving mass-transfer and heat flow theories. However, it increased linearly with the heat input per unit length, if three dimensional heat flow was not ensured because of full-penetration.
Concentrations of solutes such as magnesium, zinc, iron and silicon in the dendrite cell matrix were likely to be decreased with the increase of heat input, while those of solutes in the dendrite cell boundary to be increased.View full abstractDownload PDF (3050K) -
Basic studies on solidification mode of welds (2nd report)Toshiyasu FUKUI, Keizo NAMBA1970 Volume 20 Issue 9 Pages 458-467
Published: September 30, 1970
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThis paper discussed the effects of solidified structures of aluminum alloy welds on their several mechanical properties.
Experiments were conducted for the tests of such as tensile, bending, impact and hardness on the same specimens as those reported in the previous paper.
The properties of such as tensile, bending, impact and hardness were remarkably decreased with the growth of dendrite cells. There was a linear relationship between the tensile strength and reciprocal of square root of dendrite cell size as predicted from Petch's equation.
Concentrations of solutes such as Mg, Zn, Fe and Si in dendrite cell matrix were decreased with the growth of dendrite cells. However, they were nearly homogenized by the postweld heat treatment, except for the cases of Fe and Si.
The tendency of decreasing mechanical properties with the increase of heat input or growth of dendrite cells was scarcely affected by homogenizing, except for hardness property, although the mechanical properties in general were remarkably changed by homogenizing.
Quench-sensibility or age-hardenability of Al-Zn-Mg alloy welds was scarcely affected by the heat input in these experiments, though it was generally considered to partly depend upon the solidification rate.
It was concluded that the mechanical properties of welds were affected by the dendrite cell size, solute concentration, distribution of secondary phase, and grain structure. In particular, the effects of the former two factors were significant among them; in addition, the effects of impurities such as Fe and Si were not negligible.View full abstractDownload PDF (1809K) -
Yoshio BABA, Akira TAKASHIMA1970 Volume 20 Issue 9 Pages 468-479
Published: September 30, 1970
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (2407K)
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