Fatigue of 0.55C-1.72Si Steel with Tempered Martensitic and Carbide-Free Bainitic Microstructures
来源期刊：Acta Metallurgica Sinica2014年第1期
论文作者：Alejandro Leiro Arash Roshan Karl-Gustaf Sundin Esa Vuorinen Braham Prakash
文章页码：55 - 62
摘 要：High-Si spring steel was heat treated in three different ways:Quenching and tempering at 460 ℃ to obtain a tempered martensite microstructure,and austempering at 300 and 350 ℃,respectively,to obtain two different carbide-free bainitic microstructures.In the steel austempered at 350 ℃,both the bainite lath thickness and retained austenite content were higher than those of the steel austempered at 300 ℃.Rotating-bending fatigue tests were done in order to evaluate the effect of each heat treatment on the high-cycle fatigue behavior of the steel.When the austempering temperature was300 ℃,the endurance limit was increased by 25%despite a 5%reduction in tensile strength when compared with that of the quenched and tempered steel.The relationship between endurance limit[Rfatt（50%）]and ultimate tensile strength（Rm）was higher for the austempered samples in comparison with that of the quenched and tempered material.Therefore,it is believed that the presence of retained austenite affects the relationship between endurance limit and tensile strength.
Alejandro Leiro，Arash Roshan，Karl-Gustaf Sundin，Esa Vuorinen，Braham Prakash
Department of Engineering Sciences and Mathematics,Lule University of Technology
摘 要：High-Si spring steel was heat treated in three different ways:Quenching and tempering at 460 ℃ to obtain a tempered martensite microstructure,and austempering at 300 and 350 ℃,respectively,to obtain two different carbide-free bainitic microstructures.In the steel austempered at 350 ℃,both the bainite lath thickness and retained austenite content were higher than those of the steel austempered at 300 ℃.Rotating-bending fatigue tests were done in order to evaluate the effect of each heat treatment on the high-cycle fatigue behavior of the steel.When the austempering temperature was300 ℃,the endurance limit was increased by 25%despite a 5%reduction in tensile strength when compared with that of the quenched and tempered steel.The relationship between endurance limit[Rfatt（50%）]and ultimate tensile strength（Rm）was higher for the austempered samples in comparison with that of the quenched and tempered material.Therefore,it is believed that the presence of retained austenite affects the relationship between endurance limit and tensile strength.
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