The supercritical carbon dioxide Brayton cycle is of significant interest due to the potential for high efficiency and low capital cost compared to Rankine power cycles. Maximum temperature and pressure conditions produce higher efficiencies, leading to the desire for materials with high strength at elevated temperatures, such as INCONEL 740H. This alloy has been found to have good corrosion properties, but the mechanical and weld performance in carbon dioxide has not been studied. This study has attempted to address this issue by testing the mechanical properties in both base material and transverse gas tungsten arc welded samples before and after exposure to supercritical carbon dioxide at 750 °C, 20 MPa for 1000 h. After exposure to CO₂, base material showed an increase in strength with a moderate drop in ductility, while welded samples exhibited a decrease in both yield strength and elongation. This matched well with samples which were thermally aged in a neutral environment. Further analysis indicated the CO₂ environment had little effect beyond a depth of 5 µm of the surface, and no effect beyond 10–15 µm. The evolution of mechanical properties of 740 H in this environment, therefore, is dominated by the effect of thermal aging, with only trace impact by the CO₂ environment. The thermal aging effect was shown to be mechanically detrimental within the fusion zone of the weld due to micro-segregation during the welding process.

与兰金动力循环相比，超临界二氧化碳布雷顿循环具有很高的效率和较低的资本成本，因此引起了人们的极大兴趣。最高温度和压力条件会产生更高的效率，从而导致人们需要在高温下具有高强度的材料，例如INCONEL 740H。已经发现这种合金具有良好的腐蚀性能，但是尚未研究在二氧化碳中的机械性能和焊接性能。这项研究试图通过在750°C，20 MPa的超临界二氧化碳中暴露1000小时前后测试基础材料和横向钨极电弧焊样品的机械性能来解决此问题。暴露于CO _2后，基材显示出强度的增加，延展性适度下降，而焊接样品显示出屈服强度和延伸率均下降。这与在中性环境中热老化的样品非常匹配。进一步的分析表明，CO ₂环境在超过表面5 µm的深度时几乎没有影响，而超过10–15 µm则没有影响。因此，在这种环境下740 H的机械性能的演变主要受热老化的影响，而CO ₂环境的影响却微乎其微。由于焊接过程中的微偏析，热老化效应在焊缝的熔合区内表现为机械有害的。