Thermal Stress Cracking of Slide-Gate Plates in Steel Continuous Casting
Thermal Stress Cracking of Slide-Gate Plates in Steel Continuous Casting
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DOI：
10.1007/s11663-015-0582-9
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发表时间：
2016-04-01
影响因子：
3
通讯作者：
Kim, Seon-Hyo
中科院分区：
文献类型：
--
作者：
Lee, Hyoung-Jun;Thomas, Brian G.;Kim, Seon-Hyo
盒式组件中的滑门板控制通过中间包水口的钢流，并且可能会因热膨胀和/或机械约束而出现全厚度裂纹，从而导致空气吸入和安全问题。借助滑门板组件在螺栓预紧、预热、中间包填充、铸造和冷却阶段的热机械行为的三维有限元模型，研究了常见和罕见裂纹形成的不同机制。该模型通过之前在预热和铸造期间对钢包板进行的工厂温度测量进行了验证，然后应用于典型的中间包-水口滑动水口组件。使用该模型研究了滑动闸板中不同类型裂纹的形成机制，并使用 POSCO 的实际滑动闸板进行了评估。每块板中都存在常见的全厚度径向裂纹，这些裂纹是在铸造过程中由于内部热膨胀而在板的外表面上产生高拉应力而引起的。在上板中，这些裂纹也可能在预热或中间包填充过程中出现。螺栓过度拧紧，加上铸造过程中的热膨胀，可能会导致上板和下板出现罕见的径向裂纹。中板罕见的径向和横向裂纹似乎是由于中间包充填过程中钢水冲击中板中部，在周围耐火材料中产生拉应力而引起的。耐火材料的机械性能、螺栓紧固条件以及盒/板设计对于使用寿命都很重要。 (C) 矿物、金属与材料协会和 ASM International 2016
The slide-gate plates in a cassette assembly control the steel flow through the tundish nozzle, and may experience through-thickness cracks, caused by thermal expansion and/or mechanical constraint, leading to air aspiration and safety concerns. Different mechanisms for common and rare crack formation are investigated with the aid of a three-dimensional finite-element model of thermal mechanical behavior of the slide-gate plate assembly during bolt pretensioning, preheating, tundish filling, casting, and cooling stages. The model was validated with previous plant temperature measurements of a ladle plate during preheating and casting, and then applied to a typical tundish-nozzle slide-gate assembly. The formation mechanisms of different types of cracks in the slide-gate plates are investigated using the model and evaluated with actual slide-gate plates at POSCO. Common through-thickness radial cracks, found in every plate, are caused during casting by high tensile stress on the outside surfaces of the plates, due to internal thermal expansion. In the upper plate, these cracks may also arise during preheating or tundish filling. Excessive bolt tightening, combined with thermal expansion during casting may cause rare radial cracks in the upper and lower plates. Rare radial and transverse cracks in middle plate appear to be caused during tundish filling by impingement of molten steel on the middle of the middle plate that generates tensile stress in the surrounding refractory. The mechanical properties of the refractory, the bolt tightening conditions, and the cassette/plate design are all important to service life. (C) The Minerals, Metals & Materials Society and ASM International 2016