航空發動機用曲軸鋼の撰定竝其の將來に就て(其の 2)

概要

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In the course of this paper an additional study to the former papers (TETSU TO HAGANE, XIX, No. 4 and XX, No. 2) is reported and the results are summerized as follows. Judging from endurance strength obtained by notched bar fatigue tests, ductile steels have no inferior value to that of hard and brittle ones, while the latters show much sensitiveness for notcheffect proportional to their hardness in spite of the endurance superiority for round and smooth specimen. The hard steels, on the other hand, decrease their endurance strength very suddenly when some local stress be induced by any reason, the consequence is often proved by occurrance of a crack. It is to be beared in mind, therefor, that the surface finishing of a machine part made of such hard and brittle steel, should especially be fine and complete. As the most reliable material for crankshaft, 100_<kg> Ni-Cr steel and Ni-Cr-W steel are recommended, because the sensitiveness for notch-effect of these steels show as similar value when tempered at 500℃ as that of at 600℃, while the other materials show very much difference between both tempering temperatures. It is also suggested that almost all crankshaft steels should rather be tempered at about 500℃ than at about 600℃ in view of endurance properties.
1937-05-25