Deformation behavior, microstructure evolution, and creep damage mechanism of the novel 9Cr-3W-3Co-1CuVNbB steel CMT+P welded joint during creep

IF 4.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis Pub Date : 2025-04-24 DOI:10.1016/j.engfailanal.2025.109642

Lipeng Cai , Lei Zhao , Lianyong Xu , Yongdian Han , Kangda Hao , Haoyu Cai

{"title":"Deformation behavior, microstructure evolution, and creep damage mechanism of the novel 9Cr-3W-3Co-1CuVNbB steel CMT+P welded joint during creep","authors":"Lipeng Cai , Lei Zhao , Lianyong Xu , Yongdian Han , Kangda Hao , Haoyu Cai","doi":"10.1016/j.engfailanal.2025.109642","DOIUrl":null,"url":null,"abstract":"<div><div>To promote the widespread application of 9Cr-3W-3Co-1CuVNbB steel in ultra-supercritical (USC) power plants, this study systematically investigated the creep deformation behavior, microstructural evolution, and damage mechanisms of its welded joints. The results showed that welded joints prepared using Cold Metal Transfer with Pulse (CMT+P) exhibited superior creep resistance compared to those fabricated using Electron Beam Welding (EBW). Analysis based on Norton’s power law indicated that the deformation mechanisms of the welded joints were highly stress-dependent: under high-stress conditions, creep deformation was primarily governed by back stress, whereas under low-stress conditions, it was dominated by dislocation motion. Specifically, under high-stress creep conditions, the welded joints exhibited excellent microstructural stability, with fractures occurring in the weld metal (WM). Transmission electron microscopy (TEM) analysis revealed that dislocations accumulated extensively at martensitic laths (MLs) interfaces, leading to cracking of the lath structure. In contrast, under low-stress creep conditions, the intercritical heat-affected zone (ICHAZ) became the weak point. Dislocation tangles formed around coarsened precipitates, promoting cavity nucleation. As creep progressed, these cavities expanded along the precipitate/matrix interfaces and interconnected, eventually forming macroscopic cracks and cavity bands, ultimately resulting in brittle Type IV cracking. Classical nucleation theory analysis further indicated that dislocation density gradients and M<sub>23</sub>C<sub>6</sub> carbide coarsening were the primary factors accelerating precipitate coarsening. This study innovatively established a composite creep damage mechanism incorporating both back stress and dislocation motion deformation mechanism, elucidating the competitive damage mechanisms of CMT+P welded joints under multi-stress fields.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"176 ","pages":"Article 109642"},"PeriodicalIF":4.4000,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Engineering Failure Analysis","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1350630725003838","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}

引用次数: 0

Abstract

To promote the widespread application of 9Cr-3W-3Co-1CuVNbB steel in ultra-supercritical (USC) power plants, this study systematically investigated the creep deformation behavior, microstructural evolution, and damage mechanisms of its welded joints. The results showed that welded joints prepared using Cold Metal Transfer with Pulse (CMT+P) exhibited superior creep resistance compared to those fabricated using Electron Beam Welding (EBW). Analysis based on Norton’s power law indicated that the deformation mechanisms of the welded joints were highly stress-dependent: under high-stress conditions, creep deformation was primarily governed by back stress, whereas under low-stress conditions, it was dominated by dislocation motion. Specifically, under high-stress creep conditions, the welded joints exhibited excellent microstructural stability, with fractures occurring in the weld metal (WM). Transmission electron microscopy (TEM) analysis revealed that dislocations accumulated extensively at martensitic laths (MLs) interfaces, leading to cracking of the lath structure. In contrast, under low-stress creep conditions, the intercritical heat-affected zone (ICHAZ) became the weak point. Dislocation tangles formed around coarsened precipitates, promoting cavity nucleation. As creep progressed, these cavities expanded along the precipitate/matrix interfaces and interconnected, eventually forming macroscopic cracks and cavity bands, ultimately resulting in brittle Type IV cracking. Classical nucleation theory analysis further indicated that dislocation density gradients and M₂₃C₆ carbide coarsening were the primary factors accelerating precipitate coarsening. This study innovatively established a composite creep damage mechanism incorporating both back stress and dislocation motion deformation mechanism, elucidating the competitive damage mechanisms of CMT+P welded joints under multi-stress fields.

查看原文本刊更多论文

新型9Cr-3W-3Co-1CuVNbB钢CMT+P焊接接头蠕变变形行为、显微组织演变及蠕变损伤机制

为了促进9Cr-3W-3Co-1CuVNbB钢在超超临界电厂的广泛应用，本研究系统地研究了9Cr-3W-3Co-1CuVNbB钢焊接接头的蠕变变形行为、显微组织演变及损伤机制。结果表明，脉冲冷金属转移（CMT+P）焊接接头的抗蠕变性能优于电子束焊接（EBW）焊接接头。基于诺顿幂律的分析表明，焊接接头的变形机制高度依赖于应力，在高应力条件下，蠕变主要受背应力控制，而在低应力条件下，蠕变主要受位错运动控制。具体而言，在高应力蠕变条件下，焊接接头表现出优异的显微组织稳定性，焊缝金属（WM）出现断裂。透射电镜（TEM）分析表明，在马氏体板条界面处有大量位错积累，导致板条结构开裂。相反，在低应力蠕变条件下，临界间热影响区（ICHAZ）成为薄弱环节。在粗化析出相周围形成位错缠结，促进空洞形核。随着蠕变的进行，这些空洞沿着析出相/基体界面扩展并相互连接，最终形成宏观裂纹和空洞带，最终形成脆性IV型裂纹。经典形核理论分析进一步表明，位错密度梯度和M23C6碳化物的粗化是促进析出相粗化的主要因素。本研究创新性地建立了包含背应力和位错运动变形机制的复合蠕变损伤机制，阐明了多应力场作用下CMT+P焊接接头的竞争损伤机制。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Engineering Failure Analysis 工程技术-材料科学：表征与测试

CiteScore

7.70

自引率

20.00%

发文量

956

审稿时长

47 days

期刊介绍： Engineering Failure Analysis publishes research papers describing the analysis of engineering failures and related studies. Papers relating to the structure, properties and behaviour of engineering materials are encouraged, particularly those which also involve the detailed application of materials parameters to problems in engineering structures, components and design. In addition to the area of materials engineering, the interacting fields of mechanical, manufacturing, aeronautical, civil, chemical, corrosion and design engineering are considered relevant. Activity should be directed at analysing engineering failures and carrying out research to help reduce the incidences of failures and to extend the operating horizons of engineering materials. Emphasis is placed on the mechanical properties of materials and their behaviour when influenced by structure, process and environment. Metallic, polymeric, ceramic and natural materials are all included and the application of these materials to real engineering situations should be emphasised. The use of a case-study based approach is also encouraged. Engineering Failure Analysis provides essential reference material and critical feedback into the design process thereby contributing to the prevention of engineering failures in the future. All submissions will be subject to peer review from leading experts in the field.