Dissimilar metal welds (DMWs) between ferritic steel grades are found extensively in the construction of thermal power plants. The potential combinations and approaches for joining dissimilar ferritic steels are nearly limitless. For DMWs, the difference in alloy composition (specifically chromium and carbide-forming elements) provides the main driving force for carbon diffusion during welding, post-weld heat treatment and long-term service at elevated temperatures. Since the high temperature creep strength of local, carbon-denuded zones can be dramatically reduced from that of the parent or filler material, the service performance of ferritic DMWs can be severely reduced. This article reviews experimental observations on microstructural evolution in dissimilar ferritic welds, activities to describe the observed phenomena by modelling and simulation and discusses the performance of these welds at high temperature. Lastly, a well-engineered approach to the design of ferritic DMWs is discussed in the context of thermal power plants which are subject to damage by creep.

中文翻译：

---

铁素体至铁素体异种焊缝的显微组织特征，力学性能和高温失效

在火力发电厂的建设中，广泛发现了铁素体钢种之间的异种金属焊缝（DMW）。连接异种铁素体钢的潜在组合和方法几乎是无限的。对于DMWs，合金成分（特别是铬和碳化物形成元素）的差异为焊接，焊后热处理和高温下的长期使用过程中的碳扩散提供了主要驱动力。由于局部碳剥蚀区的高温蠕变强度与母体或填充材料相比可显着降低，因此铁素体DMW的使用寿命会大大降低。本文回顾了有关不同铁素体焊缝中微观组织演变的实验观察结果，通过建模和仿真来描述观察到的现象的活动，并讨论了这些焊缝在高温下的性能。最后，在受蠕变损害的火力发电厂中，讨论了一种设计良好的铁素体DMW设计方法。