恆溫溫度對於Ti-Ti-Mo添加界面析出物強化型雙相鋼之顯微組織以及機械性質影響

Effect of Isothermal Holding Temperatures on Microstructures and Mechanical Properties of Interphase Precipitation Strengthened Dualphase Ti and Ti-Mo-bearing Steels

蔡劭璞(S. P. Tsai) ； 楊哲人(J. R. Yang) ； 王元聰(Y. T. Wang) ； 黃慶淵(C. Y. Huang)

《鑛冶：中國鑛冶工程學會會刊》 62卷3期 (2018/09) Pp. 71-77

https://doi.org/10.30069/MM.201809_62(3).0009

摘要

本研究探討低碳低合金含鈦以及含鈦鉬複合鋼材。透過Gleeble 1500進行熱處理後，本團隊欲探討不同恆溫持溫溫度（650℃, 680℃, 700℃, and 720℃）對於界面析出物強化雙相鋼的影響。兩種鋼材的麻田散鐵百分率均控制於約15%以消除麻田散鐵相比例對於機械性質之影響。結果發現越低的持溫溫度所得到的雙相組織會較為細緻。硬度方面，肥粒鐵隨著持溫溫度下降而上升；麻田散鐵趨勢則相反。鈦鉬複合添加較鈦單一鈦添加之下肥粒鐵硬度更高；麻田散鐵趨勢亦相反。較低的持溫溫度下，機械性質顯示除了強度提升之外，延伸率並沒有減損，甚至上升。此優良的機械性能歸因於較高的肥粒鐵強度、較低的兩相硬度差異，以及雙相尺寸的降低。穿透式電子顯微鏡觀察之下，發現陣列排列間距以及面上析出物平均間距均隨著持溫溫度降低而減小；鉬能夠促進析出物生成以及防止析出物在恆溫持溫過程當中粗大化。

關鍵字

界面析出物 ； 恆溫持溫 ； 雙相鋼 ； 穿透式電子顯微鏡

並列摘要

This study investigated the effect of isothermal holding temperature on mechanical properties of Low carbon Ti and Ti-Mo-bearing steels. Utilizing the Gleeble 1500 for thermal simulation, different isothermal holding temperatures of 650°C, 680°C, 700°C, and 720°C were applied to generate different dual-phase morphology with interphase precipitation imbedded inside ferrite. Owing to different ferrite transformation kinetics at different holding temperatures and for different alloying additions, holding times were especially tuned to obtain similar volume percent of martensite (around 15%). Grain size of dualphase structures decreased with decreasing holding temperatures for both steels. The ferrite hardness increased with decreasing holding temperatures for both Ti and Ti-Mo-bearing steels; martensite hardness was on the inverse trend. Ti and Mo together made a higher ferrite hardness yet lowered martensite hardness. Carbon content in martensite was used to explain the hardness variation in martensite. For lower holding temperature, the dualphase structures had higher strength together with unchanged or better elongation for both steels. Higher ferrite strength lowered difference of ferrite/martensite hardness, and reduced dual-phase size were together used to explain the excellent mechanical behaviors. Observation by transmission electron microscopy (TEM) confirmed the existence of interphase precipitation, whose sheet spacing and intercarbide spacing decreased with decreasing temperature, and enormously increased strength contribution.

並列關鍵字

interphase precipitation ； isothermal holding temperature ； dual-phase (ferrite + martensite) steels ； transmission electron microscopy (TEM)