超急速焼戻鋼の炭化物微細分散効果とその引張特性

概要

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The purpose of this study is to investigate the tensile properties of super rapid tempering steel treated by high frequency induction heating method. In order to discuss the effect of tempering time on tensile properties, two types of specimens in which tempering time was different were prepared. Super rapid tempering specimen (IT steel) was tempered for 0.35 sec by induction heating, and conventional tempering specimen (FT steel) was tempered for 3.6 Ksec by furnace. Both of specimens were quenched by induction heating .These specimens were characterized at tensile loads at room temperature. The test result showed the both steel had almost same tensile strength however the true stress of fracture of IT steel was higher than that of FT steel. This result was explained by the reduction of area of IT steel was higher than that of FT steel. The toughness of both specimens was also evaluated by measuring the area under the nominal stress-nominal strain curves. The toughness of IT steel was 30% higher than that of FT steel. SEM observation suggested that the cementite particle of IT steel was smaller and more finely dispersed compared to FT steel.