The development and evaluation of various weldability tests and investigation of the effect of alloying contents on the weldability of Mn-Si high strength steels were performed using 12 experimental steels, with additions of 1.2% silicon and/or 1.8% manganese. The present paper describes the results of a tapered maximum hardness test, bead-bend tests and synthetic HAZ ductility test, which was newly proposed by the authors.
From above results, the main conclusions were obtained as follows:
1) From a tapered maximum hardness test, it was recognized that weld HAZ hardness was increased remarkably by manganese addition, but a little by silicon.
2) As a results of the comparison of various miniatured specimens with the longitudinal bead-bend-test specimen of Kommerell type, one small type specimen was newly introduced as a substitute for the standard type.
3) HAZ ductility which was obtained by the synthetic HAZ ductility test showed remarkable loss with increasing manganese contents but was almost unaffected by silicon contents.
4) Intimate relationships were established between the results of a small type bead-bend test and a synthetic HAZ ductility test, especially in critical hardness values which showed unsatisfactory HAZ ductility.

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Recently much efforts have been done in the field of physical chemistry of welding process. In this work an attempt is made to evaluate the sulphur distribution of basic weld metal.
The degree of basicity of slag is changed by varying the ratio of CaO to SiO₂. To remove sulphur from the weld metal a high basic slag is more effective than an acidic slag, and log K'si, s becomes propotional to the basicity B_L. The values of log K_o' and log K'_Mn can not be constant throughout the whole range of expcrimental slag, and log K'_Mn takes a higher value at the acidic side whereas log K_o' gradually increases at the basic side of slag. In the range of acidic slag log K'_Si increases proportionally to basicity.
Through deoxidation by manganese in the basic covered electrode weld metal silicon would not enter the weld metal until the basicity of slag dicreases below the B_L of 0.8.
The oxygen content of a weld metal containing sulphur is much higher than on ordinary weld metal.

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A high-voltage electrcn-beam welding machine with a maximum beam power of 1.5 kw (50 kV, 30 mA) has been operated in the Japan National Research Institute for Metals since July 1960. With this equipment, the characteristics of bead penetration and welded joints of Zirconium and Zircaloy-2, namely, microstructure, hardness, tensile and bending properties and corrosion resistance against high temperature, high pressure water studied as compared with the case of TIG welding, and the following conclusions were obtained :
(1) It is possible to make a butt-joint weld at a high welding speed such as 40 to 100cm/min up to about 2.0 mm thickness of sheet.
(2) Relationship between specific weld heat input and ratio of bead penetration-to-width is given by following equation. w/p X 100=76 log H-45
(3) About three times the specific weld heat input of electron beam welding is necessary for TIG welding to give the same bead penetration.
(4) To make a smooth and not-burn - through welding bead, it may be supposed that a low voltage type power source should be preferred type, especially, for a thin sheet.
(5) No evidence has been found to substantiate the occurrence of a change in oxygen and nitrogen composition due to this welding process.
(6) Metallography, hardness, mechanical-property evaluations and corrosion tests have revealed satisfactory properties in Zirconium and Zircaloy-2 wleded joints by this welding process.

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高張力鋼板および溶接棒の有意義な割れ試験方法を求めるために,リーハイ型U開先および鉄研式y開先の2種類の突合せ拘束割れ試験の比較検討を行なった.両試験片とも,標準のものより小型の新しい試験片を用い,引張強さ40～90kg/mm²の鋼材と低水素系および高酸化チタン系溶接棒の組合せについて割れ試験を行なった.
溶接割れの重要な諸因子,すなわち溶接入熱,予熱温度,冷却速度,割れの時期,割れ発生温度,開先形状,母材の化学組成,溶接棒の被覆系統および強さ,熱影響部の最高かたさ,溶接直後の後熱,等価炭素量等が割れの様相やルート,断面および表面における割れ率におよぼす影響について研究を行なった。
高張力鋼の溶接割れ感受性におよぼす熱的拘束(冷却速度)の影響を示すために,3種類の割れ率の値をボンドの300℃における冷却速度に対して求め,割れを生じない冷却速度から100%の割れをおこす冷却速度までの範囲で割れ率の遷移曲線をえた.そして割れ率が50%になる臨界冷却速度の値を割れ感受性指示数と名付け,割れ感受性判定の尺度として用いた.割れ発生の時期および温度を求めるために溶接部の横収縮の測定も行なった.
本研究の結果えられた結論をまとめると次のようになる.
(1)高張力鋼溶接部の割れの状態は試験片の開先形状により大きく影響され,特にリーハイ型の対称形をなすU開先と鉄研式の非対称なy開先とにおいて著しい差異がある.
(2)供試鋼材および溶接棒でみとめられた溶接割れはほとんど全部が溶接部のルートまたはビード底面から発生し,溶接金属や熱影響部に伝播した.
(3)このようなルート割れは25～200℃の予熱温度に無関係に,溶接終了後約3min以上経って,温度が90℃以下,室温近くまで冷却した後に発生した.
(4)リーハイ型U開先試験片では母材の強さや溶接棒種に無関係に割れはほとんど溶接金属に生ずる.ただし非常に延性に富む溶接金属では割れは熱影響部か溶接金属のいずれかに生ずる.
(5)鉄研式y開先試験片では低水素系溶接棒を用いたときには割れはルート(鈍角をなす側)から母材の熱影響部に沿って進んだ後,溶接金属中へ折れ曲がった.しかし熱影響部より延性の劣る溶接金属の場合には割れは溶接金属か熱影響部のいずれかに生じた、一方,高酸化チタン系溶接棒ではリーハイ型U開先の場合にみられるような溶接金属割れのみを生じた.
(6)リーハイ型U開先試験片は溶接棒の相違には非常に敏感であるけれども鋼材の相違に対しては必ずしもそうだとはいえない.鉄研式y開先試験片は鋼材の相違には非常に敏感であるけれども溶接棒の相違に対しては必ずしもそうだとはいえない.
(7)リーハイ型U開先試験片は溶接棒の割れ試験用として鉄研式y開先試験片より適している。これに対してy開先試験片は母材の割れ試験用としてU開先試験片より適している.これを誤用すれば高張力鋼板とその溶接棒の割れ感受性を正しく評価することができないであろう.
(8)対称形の60°V開先(Y開先)試験片は実用上U開先試験片と等価である.
(9)ビード表面まであらわれない割れが多いので,割れ試験ではビード表面のみではなく横断面やルートにおける割れを問題にする必要がある.
(10)予熱は割れ防止に非常に有効であり,特に引張張さのレベルが80kg/mm2級の高級高張力鋼についてその効果が著しい.
(11)80kg/mm²級高張力鋼を予熱なしで溶接した場合,溶接終了直後(2min以内)に酸素アセチレン焔により溶接部を局部的に600℃に加熱することにより冷間割れを防止することができた.
(12)割れは熱影響部の最高のかたさがある限界値以上になると急激に増大する.y開先試験片についてはその限界値が50kg/mm²級高張力鋼に対するHv310(荷重1kg)の値から80kg/mm2級高張力鋼に対するHv400の値まで変化した.U開先試験片では溶接金属のかたさの限界値は50～80kg/mm²級の溶接金属に対してHv210～320であった.
(13)鉄研式y開先試験片により求められたルートにおける割れ感受性は母材の等価炭素量と良好な相関関係が求められた。

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It is necessary to use a supplied gas having humidity as low as possible for gas-shielded metal arc welding. But it is not always easy to get everywhere the recommended gas for welding, i.e. super-pure and super-dried gas charged into a specially treated cylinder.
The authors carried out experiments about drying of gas supplied from a cylinder with some desiccants : sodium alumino silicate, activated alumina and silica gel. The dew point of the gas flowing out through a desiccator was continuously measured until the given amount of a desiccant broke. Carbon dioxide was used for the supplied gas.
The results are as follows :
1) Sodum alumino silicate has a drying capacity larger than activated alumina and silica gel. The sodium alumino silicate of 640 g warrants a supply of CO₂ gas under -25°C dew point for 112 hrs., i.e. 7 cylinders. The dew point of gas through the desiccant is under -40°C from the first cylinder to fifth.
2) Activated alumina and silica gel warrant a supply of only two cylinders of CO₂ gas under -20°C dew point through each desiccant.
3) An experimental formula was established for the relation between charged weight of sodium alumino silicate and break-time.

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