The absorption of nitrogen by molten iron alloys, such as Fe-Ta, Fe-Ni, Fe-Co and Fe-Si arc melted under nitrogen/argon atmospheres have been investigated. The results of these systems are as follows: i) The nitrogen contents of arc melted iron alloys were found to be higher than those of non-arc melted one. This difference appeared to be due to he activation of nitrogen in the arc atmosphere. ii) The effect of alloying element on the absorption of nitrogen by iron alloys under the arc differs from that of non-arc melting. For instance, in the Fe-Ta system, the amount of dissolved nitrogen initially decreases with increasing Ta content up to 3 pct Ta and then increases with increasing Ta content in next stage. From the consideration of experimental results, it has been found that above anomalous nitrogen absorption was concerned with the physical states of molten iron alloy surface under the arc. That is, thenitrogen in arc melted iron alloy is determined qualitatively by the mutual reaction between deoxydizing power of alloying element and the affinity of alloying element with nitrogen. iii) Behaviours of nitrogen absorption into iron alloys under the arc are classified in 4 types by properties of alloying element. Type Ia) The property of element: The alloying elements of Type I, V, (Nb), Ta, (Ti), Cr, (Mn) increase the solubility of nitrogen and decrease the oxygen content in iron alloys. b) The phenomenon of nitrogen absorption: The nitrogen content initially decreases with increasing the content of element and then increases with increasing the content of element. Type II a) The property of element: The alloying elements of Type II, Si, (C) decrease the solubility of nitrogen and the content of oxygen in iron alloys. b) The phenomenon of nitrogen absorption: The nitrogen content decrease drastically with increasing the content of element in the first stage and the decrement of nitrogen content is small in next stage. Type III a) The property of element: The alloying elements of Type III, Ni, Co, Mo, (Cu) (W, ) (Sn) havea little effect on the solubility of nitrogen and the oxygen content in iron alloys. b) The phenomenon of nitrogen absorption: The nitrogen content does not change by the amount of alloying element. Type IV a) The property of element: The alloying element of Type IV, (Al) has a little effect on the solubility of nitrogen but decreases the oxygen content in iron alloys. b) The phenomenon of nitrogen absorption: The nitrogen content decreases drastically with increasing the alloying element in the first stage and then does not change by the amount of alloying element.
The weldments consist of multiple-members and welded joints. The strengths of members and welded joints are random variables, and so, it of weldments is also random variable. In this report, the problem about the reliability of the multiple-member weldments on ductile tensile strength and brittle fracture strength is noted. The method of calculation for reliability of it is showed. A few considerations about matching between base metal and weld metal taking account of the reliability are done, and some calculation results about them are shown. According to these calculated results, the reliability of multi-member weldments is dependent upon the two factor, or the probability density function on the strength and toughness of base metal and weld metal, and the number of materials and welded joints. The selection of weld metal have to be done taking account of the calculations of reliability as shown in this paper.
Dispersion hardening alloys posses superior tensile properties at elevated temperature. On welding of dispersion hardening alloys, some problems regarding brittleness at the joint caused by agglomeration and decomposion of dispersed particles can be pointed out. This study is investigated on weldability of TD nickel, especially on behavior of dispersing particles in welded zone at the first step of the study on weldability of dispersion hardening alloys. Ths results obtained from this study are summarized as follows. (1) In case of fusion welding of TD nickel, fusion zone is micrographically separated into three different regions. That is Region I, Region II and Region III. Even if melting-solidification time is about 1/6 sec, its separation is occured. (2) By transmission electron microstructures of solidified TD nickel, it became evident that the previous three regions are separated by distribution of ThO2 particles. Namely, in Region I, ThO2 particles make agglomeration and growth to some degree and form the honeycomb structure. In Region II, ThO2 particles make agglomeration and growth larger than in Region I. In Region III, ThO2 particles are excluded when matrix nickel is melted and solidified, and so it had the solidified structure of pure nickel. (3) It is experimentally evident that ThO2 particles are excluded out of the surface of molten nickel, in spite of the difference of density between molten nickel and ThO2.
This paper dealt with the focusing characteristics of the beam, of which divergent angle was very large in comparison with the diffraction limitted one. In this analysis it was assumed that the beam radiated from a point diverged in a corn like shape of which axis was in the radiated direction, and that its beam energy density in the plane perpendicular to the axis was given by Gaussian curve. Mathematical fomulations which gave power density of the focused beam were expressed in the nondimensional form, and the calculated values were compared with experimental data obtained from CO2 laser beam of which divergent angle was 4-5 times the diffraction limitted one. It was shown that both were considerably coincidental. The agreement between calculated values and experimental data obtained from electron beam was also satisfactory but was not so good as the case of CO2 laser.
In this study, the improvement of hot crack sensitivity of B-1900 was investigated on the basis of the experimental results in regard to the effct of C contet on the hot crack sensitivity of Inconel 713C. According to the results, it was made clear that the crystallization of white constituents was arrested with increasing C content and the hot crack sensitivity of B-1900 under low restraint conditions could be decreased by increasing C content.
Both viscosity and self-diffusion of liquid metals obey approximately a simple form of exponential (the Arrhenius) equation. It is shown that simple empirical relationships exist between the temperature dependences (activation energy) of viscosity and self-diffusion for liquid metals and their melting points. The constant in the exponential equation can be obtained from the expressions which have been derived by authors previously. The temperature dependences of viscosity and self-diffusion of liquid metals are clasified into two groups; one is normal metals (typical metals) and the other is semi-metals. The structure factors for liquid metals can be clasified into two groups as well as the temperature dependences of viscosity and self-diffusion. Consequently, viscosities and self-diffusivities can be estimated in cases where experimental data is lacking.