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对超超临界锅炉水冷壁T23接头进行了500~650℃、0~3 000h的时效试验,分析时效对焊缝组织、硬度和韧性的影响,研究了T23接头在470℃和550℃下的蠕变断裂行为,揭示T23接头的早期失效机理.结果表明:温度对T23接头焊缝性能的影响很大,当时效温度低于550℃时,焊缝长期处于高硬度状态,有明显的时效脆化倾向,当时效温度超过600℃时,焊缝中析出碳化物,硬度降低,冲击韧性逐渐恢复;T23接头脆性失效与楔形蠕变裂纹有关;焊后热处理是防止T23接头失效的有效措施,为了保证焊后热处理的效果和接头的可靠性,建议将250HB作为焊缝硬度控制的上限.
The effects of aging on the microstructure, hardness and toughness of welded joints were analyzed at 500 ~ 650 ℃ and 0 ~ 3 000 h for T23 joints of water wall of ultra-supercritical boiler. The creep of T23 joints at 470 ℃ and 550 ℃ The results show that temperature has a great influence on the weld properties of T23 joint. When the aging temperature is lower than 550 ℃, the weld seam is in a long-term high hardness state with obvious aging embrittlement When the aging temperature exceeds 600 ℃, the carbide precipitates in the weld, the hardness decreases and the impact toughness gradually restores. The brittle failure of T23 joint is related to the wedge-shaped creep crack. The post-weld heat treatment is an effective measure to prevent the failure of T23 joint. In order to ensure Weld heat treatment effect and the reliability of joints, it is recommended to 250HB as the upper limit of weld hardness control.