55Ni-17Cr-12Fe-9Mo-2Nb-1.5Al alloy is a nickel-based superalloy (Russian designation is XH55MбЮ or KhN55MBYu, XH55) without any equivalent in American/European alloy designation. It is used in cryogenic engine of satellite launch vehicles application in two different heat-treated conditions: (1) standard aged (STA) at 730 °C/15 h + 650 °C/10 h and (2) STA + BC (brazing cycle) treatment carried out in vacuum at 1030 °C with holding time of 30 min. Due to the braze cycle adopted for manufacturing, it is essential to study the deterioration in mechanical properties, if any. Hence, the present work is carried out to understand the material behavior in tensile mode (25, 425, 575, 700 and 900 °C) for XH55 alloy in STA condition and STA + BC conditions, compared with corresponding microstructural analysis, morphology and composition using microscopy at various length scales. The tensile stress–strain curve shows characteristic sudden drops in stress with respect to strain, attributed to dynamic strain aging at different temperatures for both STA and STA + BC conditions. In STA condition, the yield strength of the material decreased with increase in temperature. In STA + BC condition, the yield strength decreased up to 425 °C, increased up to 700 °C as the material was subjected to artificial aging during testing and finally decreased at 900 °C. Marginal deterioration in mechanical properties have been observed due to the braze cycle adopted against STA condition.

中文翻译：

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用于运载火箭的镍基高温合金55Ni-17Cr-12Fe-9Mo-2Nb-1.5Al的高温拉伸行为

55Ni-17Cr-12Fe-9Mo-2Nb-1.5Al合金是镍基高温合金（俄罗斯名称为XH55MбЮ或KhN55MBYu，XH55），没有美国/欧洲合金名称。它可在两种不同的热处理条件下用于卫星运载火箭的低温发动机应用：（1）730°C / 15 h + 650°C / 10 h的标准时效（STA）和（2）STA + BC（钎焊）循环）处理在真空中于1030°C的温度下进行，保持时间为30分钟。由于用于制造的钎焊循环，必须研究机械性能的下降（如果有的话）。因此，进行本工作是为了了解XH55合金在STA条件和STA + BC条件下在拉伸模式（25、425、575、700和900°C）下的材料行为，并进行相应的显微组织分析，显微镜在各种长度尺度上的形态和组成。拉伸应力-应变曲线显示出应力相对于应变的突然下降，这归因于STA和STA + BC条件在不同温度下的动态应变老化。在STA条件下，材料的屈服强度随温度的升高而降低。在STA + BC条件下，随着材料在测试过程中进行人工时效，屈服强度下降到425°C，上升到700°C，最终在900°C时下降。由于针对STA条件采用了钎焊循环，因此观察到了机械性能的极限下降。归因于STA和STA + BC条件在不同温度下的动态应变老化。在STA条件下，材料的屈服强度随温度的升高而降低。在STA + BC条件下，随着材料在测试过程中进行人工时效，屈服强度下降到425°C，上升到700°C，最终在900°C时下降。由于针对STA条件采用了钎焊循环，因此观察到了机械性能的极限下降。归因于STA和STA + BC条件在不同温度下的动态应变老化。在STA条件下，材料的屈服强度随温度的升高而降低。在STA + BC条件下，随着材料在测试过程中进行人工时效，屈服强度下降到425°C，上升到700°C，最终在900°C时下降。由于针对STA条件采用了钎焊循环，因此观察到了机械性能的极限下降。