Ni-based superalloys IN718 and IN713LC have been joined through linear friction welding (LFW) in this study. The variation of microstructure across the weld line developed during linear friction welding and after post weld heat-treatment (PWHT) has been investigated. Their effects on microhardness have also been studied. A clean weld region which is free of micro-porosity, micro-cracking and oxides, was achieved. Dynamic recrystallisation (full and partial) occurred on both sides of the weld, which produced much finer grains in the recrystallised zone. Dissolution of ‘parent’ γʹ/γʹʹ, towards the weld line was observed on each side of the weld. However, reprecipitation of γ′ was only found in the as-welded IN713LC. All these were found to have a huge impact on the hardness profile. A softer heat affected zone (HAZ) was found in the IN718 side with the lowest hardness value achieved at an axial position 0.6 mm from the weld line. The increased dissolution of γ'/γ'´ towards the weld line resulted in decreasing hardness towards the weld line. However, the formation of refined grains closer to the weld line increased the hardness towards the weld line from axial position 0.6 mm. In contrast, a harder HAZ was found in the IN713LC side, which resulted from the formation of finer reprecipitated γ′ and recrystallised grains. PWHT brought about reprecipitation and/or further reprecipitation of γʹ/γʹʹ in the IN718 and IN713LC HAZs, resulting in stronger HAZs.

镍基高温合金IN718和IN713LC通过线性摩擦焊接（LFW）连接在一起。研究了在线性摩擦焊接过程中和焊后热处理（PWHT）之后，整个焊缝组织的微观结构变化。还研究了它们对显微硬度的影响。获得了无微孔，微裂纹和氧化物的清洁焊接区域。动态再结晶（全部和部分）发生在焊缝的两侧，在再结晶区产生了更细的晶粒。在焊缝的每一侧观察到“母体” γʹ/ γʹʹ向焊缝的溶解。但是，仅在焊接后的IN713LC中发现了γ'的再沉淀。发现所有这些对硬度分布具有巨大影响。在IN718侧发现了一个较软的热影响区（HAZ），在距焊接线0.6 mm的轴向位置处获得了最低的硬度值。γ'/γ''向焊缝的溶解度增加，导致向焊缝的硬度降低。但是，靠近焊接线的细晶粒的形成增加了从轴向位置0.6 mm向焊接线的硬度。相反，在IN713LC侧发现了更硬的热影响区，这是由于形成了更细的再沉淀γ'和重结晶晶粒所致。PWHT在IN718和IN713LC HAZ中引起γʹ/ γʹʹ的再沉淀和/或进一步再沉淀，从而导致更强的HAZ。朝向焊接线的´会导致朝向焊接线的硬度降低。然而，靠近焊接线的细晶粒的形成增加了从轴向位置0.6mm朝向焊接线的硬度。相反，在IN713LC侧发现了更硬的热影响区，这是由于形成了更细的再沉淀γ'和重结晶晶粒所致。PWHT在IN718和IN713LC HAZ中引起γʹ/ γʹʹ的再沉淀和/或进一步再沉淀，从而导致更强的HAZ。朝向焊接线的´会导致朝向焊接线的硬度降低。然而，靠近焊接线的细晶粒的形成增加了从轴向位置0.6mm朝向焊接线的硬度。相反，在IN713LC侧发现了更硬的热影响区，这是由于形成了更细的再沉淀γ'和重结晶晶粒所致。PWHT在IN718和IN713LC HAZ中引起γʹ/ γʹʹ的再沉淀和/或进一步再沉淀，从而导致更强的HAZ。