Effect of Heat-Input on Microstructure and Toughness of CGHAZ in a High-Nb-Content Microalloyed HSLA Steel

Yu, Hao; Wu, Kaiming; Dong, Baoqi; Liu, Jingxi; Liu, Zicheng; Xiao, Daheng; Jin, Xing; Liu, Hankun; Tai, Minmin

doi:10.3390/ma15103588

Cited by 7 publications

(7 citation statements)

References 22 publications

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“…The heat input of GMAW is lower than that of SMAW, which leads to finer grain in GMAW. These grains encounter difficulties in growth after nucleation due to the reduced heat input [ 34 , 35 ].…”

Section: Resultsmentioning

confidence: 99%

Inhomogeneous Strain Behaviors of the High Strength Pipeline Girth Weld under Longitudinal Loading

Zhang,

Ma,

Liu

et al. 2024

Materials

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Unforeseen failures in girth welds present a significant challenge for the pipeline industry. This study utilizes 3D Digital Image Correlation (DIC) assisted cross-weld tensile testing to analyze the strain response of high-strength thick-walled pipelines, providing essential insights into the strain migration and fracture mechanisms specific to girth welds. The results reveal that the welding process significantly affects the mechanical distribution within the girth weld. The tested Shielded Metal Arc Welded (SMAW-ed) pipe exhibited undermatched girth welds due to high heat input, while Gas Metal Arc Welding (GMAW) introduced a narrower weld and Heat-Affected Zone (HAZ) with higher hardness than the base metal, indicative of overmatched girth welds. Strain migration, resulting from a combination of metallurgical heterogeneous materials and geometrical reinforcement strengthening, progressed from the softer HAZ to the base metal in the SMAW-ed sample with reinforcement, ultimately leading to fracture in the base metal. In contrast, the GMAW-ed sample shows no strain migration. Reinforcement significantly improves the tensile strength of girth welds and effectively prevents failure in the weld region. Sufficient reinforcement is crucial for minimizing the risk of failure in critical areas such as the weld metal and HAZ, particularly in SMAW-ed pipes.

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Section: Resultsmentioning

confidence: 99%

Inhomogeneous Strain Behaviors of the High Strength Pipeline Girth Weld under Longitudinal Loading

Zhang,

Ma,

Liu

et al. 2024

Materials

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“…The typical microstructure of the weld with geometry measurements is shown in Figure 15. Table 5 shows the geometric parameters of the weld.…”

Section: Metallographic Test Resultsmentioning

confidence: 99%

“…The publication aims to prove that the ability to control the weld in the technological process based on a computational model optimizing the amount of linear energy of welding is a decisive element affecting the quality and scale of the reduction in production costs with optimized heat supply [15].…”

Section: Introductionmentioning

confidence: 99%

The Use of the Linear Energy Calculation Model in High-Frequency Induction (HFI) Tube Welding Technology to Obtain Optimal Microstructure and Weld Geometry

Techmański¹,

Stȩpień²,

Garstka

et al. 2023

Metals

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The article presents a calculation model of the linear energy of welding P235GH steel tubes with high-frequency currents in order to obtain an optimal microstructure and geometry of the weld of high internal purity. The model was developed based on real data for the standard linear energy used in the steelworks Huta Łabędy and presented as the power factor P/V and P/(V·t), where P is the power [kW], V the production speed [m/min] and t the wall thickness. The model can be used for two ranges of pipe diameters: 114.3–168.3 mm and 219.1–323.9 mm. The data from the model were implemented into the High Frequency Induction (HFI) control panel of Huta Łabędy in order to produce test tubes which were subsequently tested with ultrasounds to verify the quality of the internal weld. In addition, samples were taken for metallographic analysis, which was supposed to check whether the applied linear energy calculation model allows the obtainment of the optimal weld geometry and the optimal angle of the metal flow line allowing for swelling and the extrusion of melted impurities from the inside of the joint by the squeeze rolls. The metallographic analysis also determined the nature of the occurrence of ferrite inside of the center diffusion bond and the zonal microstructure of the joint, the control of which is based on the correlation of the parameters of the mechanical process of forming the tube with the linear energy of welding. Carrying out the technological and technical process based on the applied HFI linear energy calculation model allowed us to obtain a weld of high purity and metallurgical consistency. This model can be used in the future on an industrial scale for the production of pipes using the HFI method.

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“…As a result, the nucleation temperature of lath ferrite increased, and the lath ferrite formed at high temperature had sufficient time and space to grow, resulting in a decrease in the CGHAZ structure's uniformity, which significantly deteriorated the toughness of the CGHAZ. In addition, a higher alloy content and welding heat input promoted the formation and coarsening of martensite-austenite (M-A) components, which were the initial sources of cracks, further leading to a decrease in impact energy [32,33].…”

Section: Effect Of the Ti/n Ratio On Cghaz Microstructure And Toughnessmentioning

confidence: 99%

Effects of Ti/N Ratio on Coarse-Grain Heat-Affected Zone Microstructure Evolution and Low-Temperature Impact Toughness of High Heat Input Welding Steel

Liu,

Wang,

et al. 2023

Coatings

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Coarse-grain heat-affected zone (CGHAZ) properties of steel deteriorate when it is welded using high heat input, which always restricts the promotion and use of high heat input welding steel. TiN particles significantly inhibit the growth of austenite and improve the microstructure and properties of high heat input welding steel. Effects of different Ti/N ratios on the CGHAZ microstructure and properties of high heat input welding steel were studied using welding thermal simulations and in situ observations. Results showed that a higher Ti/N ratio led to the abnormal growth of austenite grains and promoted the nucleation and growth of lath ferrite, which made the microstructure of the CGHAZ heterogeneous. In contrast, austenite grains were more uniform at a lower Ti/N ratio. Thus, the microstructure was refined, the brittle structure was reduced, and the properties of the CGHAZ were improved. In addition, when Ti/N = 5.85, the impact absorption energy of the CGHAZ obviously fluctuated. However, when Ti/N = 2.82, the impact absorption energy of the CGHAZ was higher and more stable. These results provided a new idea for the development of high heat input welding steel based on TiN theory.

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Effect of Heat-Input on Microstructure and Toughness of CGHAZ in a High-Nb-Content Microalloyed HSLA Steel

Cited by 7 publications

References 22 publications

Inhomogeneous Strain Behaviors of the High Strength Pipeline Girth Weld under Longitudinal Loading

Inhomogeneous Strain Behaviors of the High Strength Pipeline Girth Weld under Longitudinal Loading

The Use of the Linear Energy Calculation Model in High-Frequency Induction (HFI) Tube Welding Technology to Obtain Optimal Microstructure and Weld Geometry

Effects of Ti/N Ratio on Coarse-Grain Heat-Affected Zone Microstructure Evolution and Low-Temperature Impact Toughness of High Heat Input Welding Steel

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