Mechanical Properties and Microstructural Stability of Inconel740H Welded Joint after Long-term Aging

DIAO Wangzhan; WANG Ping; ZHANG Song; ZHAO Weijun; XU Xiangjiu; HUANG Chao; ZHAO Qinglu

doi:10.7512/j.issn.1001-2303.2025.10.16

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Mechanical Properties and Microstructural Stability of Inconel740H Welded Joint after Long-term Aging
Vol. 55, Issue 10, Pages: 148-158(2025)
Received：28 August 2025，

Published：20 October 2025
DOI： 10.7512/j.issn.1001-2303.2025.10.16
稿件说明：

移动端阅览

刁旺战，王萍，张松，等.Inconel 740H焊接接头长时时效后的力学性能和组织稳定性［J］.电焊机，2025，55（10）：148-158. DOI： 10.7512/j.issn.1001-2303.2025.10.16.

DIAO Wangzhan, WANG Ping, ZHANG Song, et al.Mechanical Properties and Microstructural Stability of Inconel740H Welded Joint after Long-term Aging[J].Electric Welding Machine, 2025, 55(10): 148-158. DOI： 10.7512/j.issn.1001-2303.2025.10.16.

摘要

700 ℃先进超超临界燃煤锅炉是未来火电技术的核心研究方式。Inconel 740H是700 ℃等级机组的重要候选材料。本研究采用热丝TIG焊工艺，对固溶态Inconel 740H进行焊接，焊后进行时效强化热处理（800 ℃/4 h/AC），热处理后将焊接接头在700 ℃进行1 000 h~10 000 h等温长时时效试验，分析了时效后的微观组织稳定性和力学性能的变化趋势。结果表明：时效过程中焊接接头的母材和焊缝DCR区的γʹ相一直为球形，且粗化速率符合LSW熟化理论，焊缝IDR区在5 000~8 000 h之间的γ′相开始由球形逐渐转化为立方体。焊接接头时效至10 000 h未发现有害相析出，具有较高的组织稳定性。长时时效10 000 h后，冲击韧性由时效强化热处理后的63.4 J/cm

下降到27 J/cm

，冲击韧性的变化与晶界碳化物M

的形态和尺寸变化存在紧密关系。室温和700 ℃高温拉伸的屈服和抗拉强度从ASHT后到长时时效3 000 h后强度逐渐增加，然后随着时效时间的延长强度逐渐降低，与CRSS和γ′直径对应关系的变化趋势相一致。

Abstract

The 700 ℃ advanced ultra-supercritical coal-fired boiler represents the core research approach for future thermal power technology

Inconel740H is an important candidate material for 700 ℃ grade units. This study used the hot-wire TIG welding process to weld solid solution Inconel740H

followed by aging strengthening heat treatment (800 ℃/4 h/AC). After heat treatment

the welded joints was subjected to isothermal aging tests at 700 ℃ for 1 000-10 000 h. The study analyzes the trend of microstructural stability and mechanical properties after aging. The results indicate that during the aging process

the γʹ phase in the base metal and weld DCR zone of the welded joint remains spherical

and the coarsening rate conforms to the LSW ripening theory. Between 5 000-8 000 h

the γ′ phase in the IDR zone of the weld seam gradually transforms from spherical to cubic. No harmful phase precipitation was found in the welded joint after 10 000 hours of aging

indicating high structural stability. After long-term aging for 10 000 h

the impact toughness decreases from 63.4 J/cm

to 27 J/cm

. The change of impact toughness is closely related to the morphology and size changes of grain boundary carbides M

. The yield and tensile strengths at room temperature and 700 ℃ gradually increase from ASHT to 3 000 h of long-term aging

and then gradually decrease with extended aging time

the tren

d of change is consistent with the correspondence between CRSS and γ′ diameter.

关键词

Keywords

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