Damage analysis of T23/TP316H dissimilar metal weld for thermal power plant after service

DING Yongsan; LU Li; ZHU Hongbin; XU Jianming; ZHANG Yu; LI Kejian

doi:10.7512/j.issn.1001-2303.2021.03.11

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Damage analysis of T23/TP316H dissimilar metal weld for thermal power plant after service
Vol. 51, Issue 3, Pages: 59-63(2021)
Published：2021
DOI： 10.7512/j.issn.1001-2303.2021.03.11
稿件说明：

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DOI：

DING Yongsan, LU Li, ZHU Hongbin, et al. Damage analysis of T23/TP316H dissimilar metal weld for thermal power plant after service[J]. Eletric Welding Machine2021, 51(3): 59-63. DOI： 10.7512/j.issn.1001-2303.2021.03.11.

摘要

通过试验研究分析了服役后的高温蒸汽管道中T23/TP316H异种金属焊接接头的微观组织、成分和氧化情况。结果表明

在540℃/17 MPa条件下服役10万h后

TP316H钢侧虽会被氧化

但未发现明显的会导致接头早期失效的潜在危险因素;T23钢侧会出现沿焊缝/热影响区界面的氧化

并出现了沿界面的开裂。T23钢与镍基焊缝金属的界面氧化损伤与界面两侧热膨胀系数、高温蠕变强度差异及界面附近的硬度梯度耦合后

很可能诱发界面失效

增加接头早期失效风险。与此同时

T23钢侧未发现蠕变、碳迁移软区等常见的界面失效弱化因素

所以界面氧化损伤是T23/TP36H异种金属焊接接头的主要损伤模式。

Abstract

The microstructure

chemical composition and oxidation of the ex-service steam tube containing T23/TP316 H dissimilar metal weld were investigated to analyze damage after service. The results show that after service for 100 000 hours at 540 ℃/17 MPa

although the TP316 H steel side is oxidized

no potential risk that may cause early failure is found;however

the T23 steel side is oxidized along the weld/heat affected zone interface and cracks along the interface is observed. The coupling interaction between interfacial oxidation damage of weld metal

the differences in thermal expansion coefficient and creep strength on both sides of the interface

and the hardness gradient near the interface is likely to induce interfacial failure and increase the early failure risk of the welded joint. In addition

some common detrimental factors such as creep and soft zone induced by carbon migration are not found at the T23 steel side

thus interfacial oxidation damage is the main damage mode of joint studied in this paper.