Abstract The effect of additional heat input on the NiCrMoV weldments via thermal cycles was comparatively investigated. After thermal effect with one to three cycles and post-weld heat treatment (PWHT), no obvious changes in the microhardness and microstructure were detected in the weldments except a hardness-increased zone formed within the original weld metal (WM), which was designated as the present heat-affected zone (pre-HAZ). Compared with the tempered martensite in the as-welded WM, the tempered lath martensite with dispersed second phase particles was revealed in the pre-HAZ rooted in the original WM. Though the pre-HAZ showed larger hardness owing to microstructure change by rapid cooling during thermal simulation, yet the microhardness in this zone still did not exceed previous hardness range for each specimen. It could be concluded that the microstructure in WM remained stable and the reliable property was anticipated for this weldment even experienced further reheating e.g. repair welding process.

中文翻译：

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附加热输入对多热循环模拟的NiCrMoV焊接接头组织和性能的影响

摘要 比较研究了热循环对NiCrMoV焊件附加热输入的影响。经过 1 到 3 个循环的热效应和焊后热处理（PWHT）后，除了在原始焊缝金属（WM）内形成的硬度增加区外，焊件的显微硬度和显微组织没有明显变化，称为作为目前的热影响区（前热影响区）。与焊态 WM 中的回火马氏体相比，在根植于原始 WM 的预热影响区中显示出具有分散第二相颗粒的回火板条马氏体。尽管在热模拟过程中由于快速冷却导致的显微组织变化，pre-HAZ 显示出更大的硬度，但该区域的显微硬度仍然没有超过每个试样的先前硬度范围。