This paper reports the results of a preliminary experiment on the gas pressure welding intended for application to the welding of rails or car parts. The writer used a 25mm ∅ mild steel rod, the cut surface of which was finished by lathe. The results were as follows: 1) The max. temperature of the welded part was lower than 1200°C even with two No.10 blowpipe nozzles applied; i. e., below its melting point. 2) Metallographically, the welded part was perfect with no decarburization, but within the area of about 30mm of the joint, grain growth was recognized. 3) The writer considered many weldtng factors and established the operation standard. Whenever the operation Was carried out by this standard, the tensile strength, elongation, Charpy value and fatigue strength of the joint turned out invariably very excellent. From this experiment, he was convinced that this method would be well applicable to the intended purpose.
In this experiment, the factors affecting consistency of shear strength have been investigated. It has been discovered that it is necessary in order to attain a high degree of consistency that welding conditions be kept under control. There must be certain optimum welding conditions for securing consistency, so to find such factors affecting consistency some experiments have been performed. The following conclusions were drawn: 1) The shape of characteristic curve of consistency is “V”-type against the several welding conditions, the lowest depression representing the best condition. 2) To obtain good consistency, surface preparation is important ; the chemical method is superior to wire-brushing. 3) It appears that the shape of wave form of welding current affects consistency. 4) Especially it is important for the best results that weldtng conditions be kept as constant as possible. 5) The lighter the gage, the narrower becomes the ranw of good cosistency.
Using the U-type standard Charpy test pieces, the authors have investigated the notch toughness of four representative Japanese rimmed steels by two test methods: slow bend test and Charpy impact test. (a) To discuss the characteristics of load-deflection curve obtained at various temperatures, they adopted the following criterions: ∅=maximum load/ultimate point deflection ∅′=(maximum load) - (yielding load) /uItimate point deflection As seen in Fig.9, these values represent mean rates of strain hardening from orlginal and yieldmg load to maximum load. (b) The values of ∅ and ∅′ remained constant within their experimental temperature range (-80°C-+100°C), being independent of testing temperature. (c) From Figs.16 and 17 it can be seen that the material of which ∅ or ∅′ value is lower shows a Iower tmns tion temperature. (d) To judge the notch toughness of materials, slow bend test is more useful than Charpy test for the materials with lower transition temperatures;while Charpy test is better suited for the materials with higher transition temperatures. From (b) andd (c), it can be said that the value of ∅ or ∅′ of the material at room temperature be a cdtedon to decide the notch toughness of the material.
Arc currents flowing through some weldihg electrodes are measured with use of both an A. C. and a D. C. ammeter connected in series. Readings of the D. C. ammeter are remarkable in both iron and stainless steel electrodes having no flux, and are small, generally, in electrodes covered with fluxes. Maximum power of the welding will be secured with use of electrodes, arcs of which do not rectify.the currents.
In Report I the author obtained the values of activation energies for several electrodes made by Kobe Steel Works. In the investigation of this energy, the following points must be considered: 1) To study the relation between activation energy and metal constitution, welding conditions should be kept constant. 2) The tempering method is only an approximation; the, isothermal method must be adopted for more exact values. 3) The “;Rate Process Theory” can applicable only to the single process. 4) Activation energy can be measured in terms not only of change in hardness but in other stresssensitive physical properties, e. g., electric conductivity, coercive force, etc.
It is reliable that the water content in electrode coating (i.e., free water, combined water and chemical water) has much influences upon the partial pressure of hydrogen in arc atmosphere during metallic arc welding. Van den Blink advocated the next formula as a quantitative relation between them; F=1-PH2·(PH2O) (1/PH2+1/PH2O+1/PCO+1/PCO2) (1) When F>1, partial pressure of hydrogen increases in accordance with increase of the water content, but when F<1, the former decreases in spite of increase of the latter. Our experiments on this problem are as follow:(1) We calculated F in (1) theoretically at various compositions of arc atmosphere using water gas reaction at 1400°C, 1530°C, 1600°C and 1700°C, and determined the diagram of F=0. (2) Electrodes experimentaly used were three kinds of cellulose types, three limestone types, three deoxide types and four kinds of cellulose-limestone types. They were mixed with same base mixing. (3) The free water and other types of water in electrode coatings were separatly measured at 110°C and 1100°C. Arc atmosphere generated from drying and non-drying (as wet) electrodes were collected and analized. (4) The principal conclusions obtained were as follow:(a) When cellulose type electrodes were used, the partial pressure of hydrogen was very little affected by drying or non-drying of the electrode coatings. (b) When other type electrodes, particularly limestone types, were used, the partial pressure of hydrogen from non-drying electrode showed remarkable increase than that from drying electrode.Therefore, electrodes, except cellulose types, must be dried sufficiently before they are used in welding.