巻号一覧
34 巻, 3 号
選択された号の論文の6件中1～6を表示しています
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池田 一夫1965 年 34 巻 3 号 p. 285-300
発行日: 1965/03/25
公開日: 2011/08/05
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村本 徹五郎1965 年 34 巻 3 号 p. 301-309
発行日: 1965/03/25
公開日: 2011/08/05
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守田 貞義, 佐藤 誠, 藤本 優1965 年 34 巻 3 号 p. 310-321
発行日: 1965/03/25
公開日: 2011/08/05
ジャーナル フリーFatigue strength of a quenched and tempered steel does not increase so much as the static strength increases in mill scaled state or in welded joints. Therefore, the authors have made a study on the effect of shot blasting and subsequent heat treatment on the mechanical properties of two quenched and tempered steels as one of the means for improving the fatigue strength of a high tensile steel.
The results indicate that shot blasting raises the pulsating tension fatigue limit by about 10 to 50% on both quenched and tempered plate and welded joints.
The treatment alone heating up to just below the Al transformation temperature followed by a rapid cooling, hardly improved the fatigue strength of a plate, while in case of welded joints it was as much effective as shot blasting.
The aging after shot blasting gave a favourable effect on the fatigue strength, however, it lowered the toughness of surface region and the shear lips in full thickness V-Charpy impact test specimen tested at low temperatures were little observed.
On the other hand, when the test was conducted after shot blasting and tempering treatment, heating up to just below the Al transformation temperature followed by quenching from the temperature, both fatigue strength and toughness of surface region were excellent. The results also indicate that the shot blasting treatment between normal pressure quenching and tempering process brought forth the same effect as stated before. The heat treatment after shot blasting could be replaced by line heating treatment and even with the line heating treatment alone the fatigue strength was fairly improved so long as welded joints were concerned.
With the shot blasting and following aging treatment the fracture transition temperature of V-Charpy impact test was transferred upward by about 10°C, however, the NDT temperature of the NRL drop weight test was slightly influenced.抄録全体を表示PDF形式でダウンロード (2142K) -
稲垣 道夫, 和田 次康, 宇田 雅広1965 年 34 巻 3 号 p. 322-329
発行日: 1965/03/25
公開日: 2011/08/05
ジャーナル フリーThe nitrogen content of arc-melted liquid iron has been measured in the atmosphere of argon containing nitrogen with various partial pressures. The arc melting was carried out in a small vessel, in which the controlled gas mixture flowed, under the condition of an arc-current of 180 A and straight polarity for the non-consumable tungsten electrode. By a preliminary experiment, the temperature of the molten pool was measured as about 1, 800°C by using W-W.Re thermocuple.
The results obtained were as follows:
(1) The nitrogen content of the arc-melted pure iron is proportional to the square root of the partial pressure of nitrogen up to about 0.09 atm PN2, and above 0.09 atm the nitrogen content becomes a nearly constant value.
(2) In the range of the nitrogen partial pressure lower than 0.09 atm, the nitrogen content of the arc-melted iron is about 5.2 times higher than the value expected from the solubility of nitrogen in the ordinary, non-arc melting. Such anomalous high dissolution of nitrogen may be caused by the activation of nitrogen in the atmosphere by arc.
(3) From the difference of the nitrogen content in iron between the arc melting and the non-arc melting, the free energy difference 4F40 between the activated and the ordinary nitrogen is obtained to be 6.82 Kcal/g·atm at 1, 800C. If it is assumed that the activation of nitrogen is essentially the dissociation of the nitrogen molecule to the atomic nitrogen, the above energy difference corresponds to the dissociation constant of 0.15.
(4) Calculating the dissociation equilibrium of nitrogen from its dissociation energy and the specific heats of each species, it is shown that the dissociation constant reaches 0.15 at 5, 100C. This is the apparent temperature which the arc-atmosphere would reach in the arc-column, if it is assumed that the composition of the nitrogen gas in the vicinity of the metal surface is the same as that in the arc-column.抄録全体を表示PDF形式でダウンロード (2699K) -
伊籐 梯二, 西 武史, 森山 康, 豊福 勝人1965 年 34 巻 3 号 p. 330-341
発行日: 1965/03/25
公開日: 2011/08/05
ジャーナル フリーRecent trend in railroads in definitely toward use of long rails. In Japan also, this trend is increasingly obvious.
The production of weld rails has been started for this purpose. We began to develop the technic of pressure welding by High frequency., making it possible for us to regularly produce weld rails.
Follwing is characteristics of this welding process and the sammaries of results of various tests on weld rails.
(1) The most important characteristics of the high frequency pressure welding method are that the reliability on the reproducibity of the joint strength is large, and that the strength is very large.
(2) Necessary conditions required for successful performance of high frequency pressure weld-ing are that the upset is made after satisfactory heating.
Satisfactory joints are obtained under similar welding conditions for both 50T and 50N Rails.
(3) According to the results of bending tests performed with pressure welded actual rails, the strength was 112, 500-122, 000 Kg for head up and 113, 500-127, 000 Kg for head down with 50T pressure welded rails.
These values are larger than the values specified by the National Railways for pressure welded rails by more than 10, 000 Kg. These values are quite satisfactory.
(4) By the falling weight test performed by the step up method based upon the JIS specific-ations, the non breakage height of 50 N Rails was 2 m at the least and 3.5 m at the most, and those of 50 T Rails were 3 m at the least and 5 m at the most.
These are much above the specifications given by the Notional Railways. These results are better than those of Rails, welded by different methods, namely, flush butt welded Rails, . Gas pressure welded Rails, and so on.抄録全体を表示PDF形式でダウンロード (14310K) -
尾崎 秋男1965 年 34 巻 3 号 p. 342-347
発行日: 1965/03/25
公開日: 2011/08/05
ジャーナル フリーWhen work hardened materials of corrosion-resistant aluminum alloy are welded, the hardness increased by the cold working is softened partially welding heat. and also the mechanical strength locally is reduced and then the joint efficiency falls naturally.
Therefore, in this investigation, the author inquired into the generating condition of softened zone using A2P7-1/4 H work hardened materials of 0.5cm thick plate and simultaneously investigated about the countermeasure for the falling of the strength of the joint by the generation of the softened zone.
The author measured the thermal cycle in each point of heat affected zone and made sure that the softened degree by welding heat was depended upon the degree of the influence of the heating largely on the neak temperature
Consequently, in this experiment the author found that the softening began at about 300°C and proceeded gradually beyond this temperature and then completed perfectly at about 500°C; and also width of softened zone was increased and the strength of the joint was reduced proportionally to the welding heat.
The author made clear that to raise the joint efficiency up to 100 per cent without falling of the strength of the joint in welding the width of the softened zone ought to be kept under 0.8cm; from the relation of the width of the softened zone and the strength of joint.
Next, the author tried an improvement of the strength of the joint by PEENING method, and consequently made clear that this PEENING method was comparatively way.抄録全体を表示PDF形式でダウンロード (418K)
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