Xueda Li, Zhangyi She, Xunyun Lv, Zeyang Zhang, Liying Li, Bin Han
Softening in the heat-affected zone (HAZ) of high-strength pipeline welds compromises its service safety but the corresponding softening mechanism is not well-understood. Softening behavior in the HAZ of two X80 pipeline girth welds with different base metal microstructures, i.e., acicular ferrite (AF)-dominated (X80-AF) and granular bainite (GB)-dominated (X80-GB), were investigated through microhardness tests and detailed microstructure characterization. The results showed that softening in the HAZ of two girth welds primarily occurred in the fine-grained (FG) HAZ, while hardening was found in the coarse-grained (CG) HAZ. X80-AF showed higher softening resistance than X80-GB, with softening ratios of 3.44% vs. 12.46%, and softened zone widths of 2.1 mm vs. 3.9 mm, respectively. Due to its high dislocation density and refined interlocking structure, AF could effectively inhibit phase transformation and grain coarsening during reheating, which resulted in smaller grains and a lower fraction of polygonal ferrite (PF) in the FGHAZ (28%). In contrast, coarse GB was more prone to grain coarsening and hence engendered higher PF proportion (68%). Therefore, for the microstructural design of high-strength pipeline steels, increasing the proportion of refined AF is beneficial to the softening resistance and thereby elevates the service safety of pipelines. Bibliographic record: Metals 2026, 16(3), 247. Published 25 February 2026. Journal article. English. DOI: 10.3390/met16030247. Source: https://www.mdpi.com/2075-4701/16/3/247 Open-access evidence: copyright 2026 by the authors; Creative Commons Attribution 4.0 (CC BY 4.0), stated on the publisher page and PDF first page. License: https://creativecommons.org/licenses/by/4.0/ Primary subject: Alloy Metallurgy. Alloy: X80 pipeline steel. Process: gas metal arc welding; heat-affected-zone microstructure and softening.
@article{6981b414-e7b7-4c01-aaff-0327c633eadd,
title={Effect of Base Metal Microstructure on Softening Behavior of the Heat-Affected Zone of X80 GMAW Girth Weld},
author={Xueda Li and Zhangyi She and Xunyun Lv and Zeyang Zhang and Liying Li and Bin Han},
year={2026},
language={en}
}TY - JOUR TI - Effect of Base Metal Microstructure on Softening Behavior of the Heat-Affected Zone of X80 GMAW Girth Weld AU - Xueda Li AU - Zhangyi She AU - Xunyun Lv AU - Zeyang Zhang AU - Liying Li AU - Bin Han PY - 2026 LA - en ER -
Robert A. Francis
This document serves as a comprehensive introduction to the metallurgy of steel and its alloys, focusing on various aspects of iron and steel manufact
Wei Xu, Gaojian You
The surface properties of aviation titanium alloys critically influence service safety and reliability, yet there is limited guidance on laser power s
Unknown, Unknown
This chapter discusses metal casting processes, highlighting the diversity and common characteristics among them. The objective is to elucidate the fu
Unknown, Unknown
This study focuses on the fundamental characteristics of solid iron, which is predominantly composed of iron atoms and provides a basis for understand
Ir. Méshac KIME ILUNGA
Ce document traite des procédés métallurgiques spéciaux, en mettant particulièrement l'accent sur l'extraction liquide-liquide, un processus mis au po