This study aims to investigate the influence of Y content on grain refinement in the simulated coarse-grained heat-affected zone (CGHAZ) of X70 pipeline steels. The results explored that two different grain refinement mechanisms were presented in 0.034 wt.%-Y and 0.075 wt.%-Y steels, respectively. The Y2O2S inclusions and YP precipitates are formed in 0.034 wt.%-Y steel instead of the YP inclusions and more YP precipitates in 0.075 wt.%-Y steel. The grain refinement mechanism in the simulated CGHAZ of 0.034 wt.%-Y steel mainly depends on the formation of acicular ferrite induced by Y2O2S inclusion. Whereas, the grain refinement mechanism in the simulated CGHAZ of 0.075 wt.%-Y steel primarily relies on the austenite boundary pinning effect by higher density of YP precipitates.

中文翻译：

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Y含量对X70管线钢模拟粗粒热影响区晶粒细化影响的比较研究。

本研究旨在探讨X管线钢在模拟粗粒热影响区（CGHAZ）中Y含量对晶粒细化的影响。结果发现，在0.034 wt。％-Y和0.075 wt。％-Y钢中分别存在两种不同的晶粒细化机理。在0.034 wt。％-Y钢中代替YP夹杂物形成了Y2O2S夹杂物和YP析出物，在0.075 wt。％-Y钢中形成了更多的YP析出物。0.034 wt。％-Y钢的模拟CGHAZ中的晶粒细化机理主要取决于Y2O2S夹杂物引起的针状铁素体的形成。然而，0.075 wt。％-Y钢的模拟CGHAZ中的晶粒细化机制主要依赖于YP析出物密度更高的奥氏体边界钉扎效应。