Internal Quenching is an innovative heat treatment method for difficult to access component sections. Especially, the microstructure, as well as the residual stress state at inner surfaces, of thick-walled tubes can be adjusted with the presented flexible heat treatment process. Based on multiphysical FE-models of two different steels, a simulative optimization study, considering different internal quenching strategies, was performed in order to find the optimal cooling conditions. The focus hereby was on the adjustment of a martensitic inner surface with high compressive residual stresses. The simulatively determined optimal cooling strategies were carried out experimentally and analyzed. A good agreement of the resulting hardness and residual stresses was achieved, validating the presented Fe-model of the Internal Quenching process. The shown results also indicate that the arising inner surface state is very sensitive to the transformation behavior of the used steel. Furthermore, the presented study shows that a preliminary simulative consideration of the heat treatment process helps to evaluate significant effects, reducing the experimental effort and time.

中文翻译：

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考虑基于模拟的优化，通过内部淬火热处理改善厚壁管的内表面状态

内部淬火是一种创新的热处理方法，适用于难以接近部件的部位。特别是，厚壁管的微观结构以及内表面的残余应力状态可以通过提出的柔性热处理工艺进行调节。基于两种不同钢的多物理场有限元模型，进行了考虑不同内部淬火策略的模拟优化研究，以找到最佳的冷却条件。因此，重点是调整具有高压缩残余应力的马氏体内表面。通过仿真确定了最佳冷却策略，并进行了分析。所得硬度和残余应力的良好一致性得以实现，从而验证了所提出的内部淬火过程的铁模型。所示结果还表明，所产生的内表面状态对废钢的相变行为非常敏感。此外，目前的研究表明，对热处理过程的初步模拟考虑有助于评估显着效果，从而减少了实验工作量和时间。