新课程背景下高中政治生成性教学实施策略

摘要

This study aims to clarify the behavior of inclusions containing CaO, the inclusions which can adversely affect the fatigue life of bearing steel. Focus was placed on the behavior of the CaO containing inclusions during ladle furnace (LF) treatment. A tracer element was added to the top slag prior to the LF treatment to identify the origin of the inclusions. As a result, the main origin of the CaO element in the inclusions is LF top slag entrapped during gas stirring, and this is confirmed by the formation kinetics of the inclusions. The qualify of ultrafine bearing steel was improved by applying countermeasures to suppress slag entrapment.%軸受鋼は産業機械にとって欠かすことのできない重要素材であり，高い信頼性が求められている。軸受鋼にとって最も重要な特性は転動疲労寿命であり，その支配要因は非金属介在物であることが知られている。