摘要
针对镍基合金Inconel 617焊接接头在不同高温时效试验条件下的焊缝组织形貌及第二相粒子分布状况进行了系统研究,探究组织形貌演化对冲击韧性的影响规律。焊接接头在750℃下经过1 000h、2 000h、4 000h时效试验,通过硬度、冲击功测试反映力学性能变化,通过光学显微镜以及高分辨扫描电子显微镜对时效试验过程中的组织进行分析。时效试验后焊缝硬度升高,冲击功先升高后下降,试验前后析出相类型不变,主要为M_(23)C_6、M_6C及Ti(C,N),碳化物种类对冲击韧性影响不大。时效试验至4 000h,晶界与晶内出现针状碳化物,晶内碳化物团簇分布,碳化物析出的不均匀性使冲击功明显下降。时效试验过程中碳化物形貌的变化对冲击韧性有较大影响,特别是碳化物呈针状或团聚长大时,会降低冲击韧性,而B的加入使得这个粗化过程减弱,从而利于长期服役过程性能的稳定。本研究可为镍基合金焊接接头在750℃下的长期使用提供参考。
Microstructure and the distribution of second phases in Inconel 617 welded joint was systematically studied, the effect of microstructure on impact toughness was explored. After aging for 1 000 h, 2 000 h and 4 000 h at 750 ℃, the micro-hardness and impact has been tested to reflect the change in mechanical properties. The second phases were investigated by high resolution scanning electron microscope, and were identified as M23C6, M6C and Ti（C, N） as welded and after aging. During aging, it was indicated that the micro-hardness has increased, the impact energy increased at first and then decreased. After aging for 4 000 h, needle-like carbides precipitated both along grain boundaries and inside the grains, and there were carbide clusters inside grains. The irregular precipitation and needle-like character of carbides resulted in impact toughness degradation. However, the addition of B could weaken carbide coarsening, and it would benefit for the properties under long-term service. This research could provide a reference for long-term use of Ni-based alloy weld joint at 750 ℃ .
出处
《热力透平》
2017年第1期1-5,共5页
Thermal Turbine
