Aiming at the requirements of structural steel in Gen-IV nuclear reactor, the high-chromium martensitic heat-resistant steels containing 10–12% chromium were developed. The toughness of heat-affected zones (HAZs) is one of the important factors for evaluating the weldability of steels. In this paper, the simulated HAZs were fabricated using tempered SIMP steels. The effects of microstructures on the impact toughness of materials were analyzed using Vickers hardness tester, optical microscope, transmission electron microscope. Experimental results demonstrated that the HAZs of weldment were poor in toughness, much lower than that of the base metal. However, after experiencing post-weld heat treatment, the toughness of the HAZs increased greatly. The toughness became better in terms of CG-HAZ, FG-HAZ and IC-HAZ for the two steels, regardless of as-welded or after PWHT. Compared with SIMP7 steel, chemical compositions, such as C, Si, Mn and Cr, were adjusted to a lower content; the toughness of base metal and simulated HAZs was better in the case of SIMP11. The conjunct roles of dislocation density and carbon contents retained in the martensite led to poor impact toughness of the as-welded HAZs, because dislocations and carbon atoms affected the inner stresses within lattices.

中文翻译：

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11Cr耐热钢热影响区的冲击韧性

针对第四代核反应堆结构钢的要求，开发了含铬量为10-12％的高铬马氏体耐热钢。热影响区（HAZs）的韧性是评估钢可焊性的重要因素之一。在本文中，使用回火的SIMP钢制造了模拟的热影响区。用维氏硬度计，光学显微镜，透射电子显微镜分析了显微组织对材料冲击韧性的影响。实验结果表明，焊件的热影响区韧性较差，远低于母材。但是，经过焊后热处理后，热影响区的韧性大大提高。两种钢的CG-HAZ，FG-HAZ和IC-HAZ的韧性都更好，不论是焊后还是焊后热处理。与SIMP7钢相比，将C，Si，Mn和Cr等化学成分调整为较低的含量；在SIMP11的情况下，贱金属和模拟的热影响区的韧性更好。马氏体中位错密度和碳含量的共同作用导致焊接后的热影响区的冲击韧性较差，这是因为位错和碳原子影响了晶格内的内应力。