Behaviors of Embrittlement and Softening in Heat Affected Zone of High Strength X90 Pipeline Steels

IF 0.3 4区材料科学 Q4 METALLURGY & METALLURGICAL ENGINEERING

Soldagem & Inspecao Pub Date : 2019-01-01 DOI:10.1590/0104-9224/SI24.15

Yu Gu, F. Xiao, Yongsheng Zhou, Jin Li, Caiyun Xu, Xiaodong Zhou

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引用次数: 2

Abstract

The embrittlement and softening behaviors in heat affected zone of X90 pipeline steel were studied, and the influence of weld thermal cycle on microstructure and mechanical properties were discussed by combining the effect of peak temperature on the phase transition point (Ar3). Results show that there are embrittlement and softening zones existed in heat affected zone of X90 pipeline steel. The peak temperature greatly affected the austenitizing and its grain size, thereby affected phase transition during cooling process. The embrittlement in critical heat affected zone at 750 °C was caused by brittle bainite and M /A islands formed during cooling, because little austenite was formed during heating. While, the embrittlement in coarse grain heat affected zone was caused by austenite grain coarsen, which transformed to the coarse bainite after cooling. The softening zone attributed to the polygonal ferrite and granular ferrite after cooling, which came from fine and ununiformed austenite formed during reheating process. Ar3 decreased with the increase of Cu, Cr or Mo content in steel, and the BF content in CGHAZ and GB and AF content in FGHAZ increased. Key-words: Pipeline steel; HAZ; Mechanical property; Phase transition temperature; Chemical composition.

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高强度X90管线钢热影响区的脆化软化行为

研究了X90管线钢热影响区的脆化和软化行为，并结合峰值温度对相变点Ar3的影响，讨论了焊接热循环对组织和力学性能的影响。结果表明:X90管线钢热影响区存在脆化和软化区;峰值温度对奥氏体化及其晶粒尺寸影响较大，从而影响冷却过程中的相变。在750℃临界热影响区，由于加热过程中很少形成奥氏体，在冷却过程中形成脆性贝氏体和M /A岛。粗晶热影响区的脆化主要由奥氏体晶粒粗化引起，冷却后晶粒粗化转变为贝氏体。软化区主要为冷却后的多边形铁素体和粒状铁素体，它们来自于再加热过程中形成的细小而不均匀的奥氏体。随着钢中Cu、Cr、Mo含量的增加，Ar3含量降低，ghaz中BF含量和ghaz中GB、AF含量增加。关键词:管线钢;热影响区;力学性能;相变温度;化学成分。

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来源期刊

Soldagem & Inspecao 工程技术-冶金工程

CiteScore

1.00

自引率

16.70%

发文量

审稿时长

12 weeks

期刊介绍： The Journal Soldagem & Inspeção (S&I) js a techno-scientific journal created in 1995. Printed issues of this journal are distributed free of charge to libraries in Brazil, Latin America and the Iberian Peninsula. It has been printed regularly every quarter since September, 2002, and, since the beginning of 2007, its electronic version is available in the address: (http://www.abs-soldagem.org.br/s&i/). The journal is sponsored by the Brazilian Welding Association (ABS). Since its creation several well known professionals working in welding contributed with the Journal Soldagem & Inspeção and its editorial board crosses the Brazilian borders. During its evolution the Journal received ta special contribution from the Editors-in-chief : Ronaldo Paranhos, Américo Scoti, Paulo Modenesi e Alexandre Bracarence. Since January 2012 the Editor-in-chief is Ana Sofia C. M. D’Oliveira, Full professor at Universidade Federal do Paraná (UFPR) . Her work focus mainly on Hardfacing and Physical Metallurgy. The jornal Soldagem & Inspeção also counts with 10 Associate Editors and a fix Editorial board of referees. short-term (Ad Hoc) referees can be invited to evaluate some papers submitted to the journal. The Soldagem & Inspeção journal is the scientific divulgation channel of the Brazilian Welding Association (ABS). It aims to publish original papers related to the scientific and technological development of welding, inspection, and related fields. Review papers or letters on current and controversial subjects are also published in the Journal. Its abbreviated title is Soldag. insp. (Impr.), which should be used in bibliographies, footnotes and bibliographical references and strips.