バネ板繰返曲げ試驗機並にその使用成績に就て
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概要
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In order to select the most suitable treatment for carbon steel and siliconmanganese steel among various heat treatments which are now prevailing for flat spring plates for carriages, a special repeated bend testing machine has been manufacture, which is convenient for the comparison of the durability for repeated bending of test pieces similar to the actual materials variedly heat-treated. One of the special features of the machine is that the test piece is freely supported at its ends and the load is hung at two positions near the middle of the span so as to enable bending very similar to the actual operating condition of the flat spring ; whilst another special feature is that two test pieces may simultaneously be subjected to the repeated bend test at a rate of 500 times per minutes and the deflection of the test piece may suitably be adjusted to the thickness and deformation of the test piece so as to produce always a bending stress of 70 kg. per sq. mm. at the instant of the maximum bending until the test piece breaks down. With this testing machine, 820 test pieces of carbon steel and silicon-manganese steel spring plates subjected to two kinds of single quenching (tempered by waste heat of quenching) and the same number of test pieces subject to two kinds of double quenching (independently tempered and heated) as well as 1CO test pieces subjected to emulsified oil quenching (a sort of single quenching) were tested. The results indicate that the double quenching after independent heating for shaping and quenching is the most suitable as the heat treatment, and that carbon steel (SP 75, about 0.8%C) appears to be suitable as a spring material. Further, the test pieces which were ground to the extent of removing the decarburized surface layer were experienced to be highly durable, and this fact may be considered to endorse the effect of grinding dealt with in Mr. R. G. Batson's paper which was read before the World Engineering Congress, 1929. (Paper No. 226). It was also observed that the durability of silicon-manganese steel is unexpectedly small in comparison with its elastic limit. This may be considered to be the bad effect of grain disposition of silicates separated in the structure or the effect of decarburized layer or uneven hardeness (silicon-manganese steel being deeply decarburized in comparison with carbon steel and liable to the occurrence of uneven hardness in the central part), so that further investigation is necessary and the author retains the problem until the future occasion.
- 社団法人日本鉄鋼協会の論文
- 1938-07-25