高湿度下における 80kg/(mm)^2 級高張力鋼の溶接割れの研究

概要

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In order to prevent the cracking in the weldments under the humid atmosphere some considerations on the adequate control of welding material and on the welding process are conducted. H-type restraint cracking tests are carried out under the various intensities of restraint and diffusible hydrogen contents. The results are summarized as follows; (1) It is found clearly that MIG welding is the most suitable process in the humid atmosphere because of its low mixing ratio of the air into the arc atmosphere. (2) Absorption characteristics of the electrode coating mainly depend on the absorption to the binder and that to the capillary tubes with various radii, and the moisture content in the coating υ is given by υ=υ_e(1-e^<-α't>) where υ_e is an equilibrium moisture content, α' is a constant depending on the surface construction and t is an absorbent time. (3) The water vapor is perfectly dissociated in the arc column, and then it acts on the diffusible hydrogen in the weld metal as the same manner as hydrogen in the arc column. (4) The diffusible hydrogen content in weld metal will more contribute to the crack sensitivity of HT-80 weldments than the intensity of restraint. (5) Root cracks observed in HT-80 weldments initiate either at the unmixed or transition zone in the neighborhood of weld bond. Therefore, it can be estimated that the chemical composition of weld metal also affects the crack sensitivity.
社団法人溶接学会の論文
1973-12-25