Effect of secondary peak temperature on microstructure and toughness in ICCGHAZ of laser-arc hybrid welded X100 pipeline steel joints

Qi, Xiaonan; Di, Hongshuang; Wang, Xiaonan; Liu, Zhenguang; Misra, R.D.K.; Huan, Pengcheng; Gao, Yuan

doi:10.1016/j.jmrt.2020.05.016

Cited by 30 publications

(8 citation statements)

References 32 publications

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“…In the multi-pass joining of UHSS, ICR-CGHAZ shows noticeable microstructural changes in the HAZ. The coarse-structured CGHAZ is reheated to the austenite phase region by a second or third welding thermal cycle [43]. In these areas, the newly formed austenite nucleates at the boundaries of the PAG.…”

Section: Resultsmentioning

confidence: 99%

The effect of heat input in multi-pass GMAW of S960QL UHSS based on weaving and stringer bead procedure on microstructure and mechanical properties of HAZ

Mert,

Gurol,

Tumer

2023

Mater. Res. Express

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Quenched and tempered S960QL (yield strength ≥ 960 MPa) ultra-high strength steel (UHSS) thick plates were joined by multi-pass robotic gas metal arc welding (GMAW) using weaving and stringer bead techniques. The effects of microstructural changes in heat-affected zone (HAZ) of the joint on toughness and hardness were examined. Weaving and stringer bead techniques applied for the multi-pass welding procedure altered average peak temperatures and exposure time to those temperatures. Mechanical properties of HAZ were evaluated by utilizing notch impact and hardness tests, and these results were correlated with microstructural characterizations using optical and scanning electron microscopes. Prior austenite grain (PAG) coarsening occurred because of increased exposure time to peak temperature in coarse-grained HAZ (CGHAZ) of the W-5 (weaving pass) joint. CGHAZs at the face pass, which have not been subjected to a second thermal cycle, have the highest hardness in both joints. Although standard toughness requirements are met in both joints, since HAZ in the S-12 (stringer bead) joint is narrow compared with the one in the W-5 joint, impact toughness values were higher with the S-12 joint due to the locations of the notches of the impact specimens.

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Section: Resultsmentioning

confidence: 99%

The effect of heat input in multi-pass GMAW of S960QL UHSS based on weaving and stringer bead procedure on microstructure and mechanical properties of HAZ

Mert,

Gurol,

Tumer

2023

Mater. Res. Express

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“…The initial temperature of the first pass was assumed at the room temperature (25 °C) while, for the second pass, the value was set to 150 °C. Because of the technological limitations of the dilatometer, the samples were heated up to 1100 °C with a heating rate of 100 °C/s whilst the holding time was set at 3 s. The cooling profile was set in order to guarantee the cooling time between 800 °C and 500 °C (t8/5) of about 25 s [ 41 , 42 ]. The second peak of weld conditions, with a peak temperature in the inter-critical zone, was selected by considering the values of critical temperature Ac1 and Ac3.…”

Section: Methodsmentioning

confidence: 99%

Influence of Vanadium Micro-Alloying on the Microstructure of Structural High Strength Steels Welded Joints

Stornelli

Tselikova²,

Gattia

et al. 2023

Materials

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The inter-critically reheated grain coarsened heat affected zone (IC GC HAZ) has been reported as one of the most brittle section of high-strength low-alloy (HSLA) steels welds. The presence of micro-alloying elements in HSLA steels induces the formation of microstructural constituents, capable to improve the mechanical performance of welded joints. Following double welding thermal cycle, with second peak temperature in the range between Ac1 and Ac3, the IC GC HAZ undergoes a strong loss of toughness and fatigue resistance, mainly caused by the formation of residual austenite (RA). The present study aims to investigate the behavior of IC GC HAZ of a S355 steel grade, with the addition of different vanadium contents. The influence of vanadium micro-alloying on the microstructural variation, RA fraction formation and precipitation state of samples subjected to thermal cycles experienced during double-pass welding was reported. Double-pass welding thermal cycles were reproduced by heat treatment using a dilatometer at five different maximum temperatures of the secondary peak in the inter-critical area, from 720 °C to 790 °C. Although after the heat treatment it appears that the addition of V favors the formation of residual austenite, the amount of residual austenite formed is not significant for inducing detrimental effects (from the EBSD analysis the values are always less than 0.6%). Moreover, the precipitation state for the variant with 0.1 wt.% of V (high content) showed the presence of vanadium rich precipitates with size smaller than 60 nm of which, more than 50% are smaller than 15 nm.

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“…Therefore, research on the effects of secondary welding thermal cycles mainly focuses on its effects on the microstructure and properties of CGHAZ [2,3]. In the reheated CGHAZs, the severely coarse M/A constituents are formed in the inter-critically reheated CGHAZ (ICCGHAZ), whose secondary peak temperature is between Ac 1 and Ac 3 , resulting in the sharp decrease in toughness [4][5][6]. It has been found that the heat from extra weld pass may decrease the number of cracks, and may change their characteristics to improve the mechanical properties of the steel [7].…”

Section: Introductionmentioning

confidence: 99%

Study on Corrosion Resistance and Hydrogen Permeation Behavior in Inter-Critically Reheated Coarse-Grained Heat-Affected Zone of X80 Pipeline Steel

Zhao

Xiao

et al. 2022

Metals

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We studied the effects of peak temperature and cooling rate in the secondary welding thermal cycles on the martensite/austenite (M/A) constituents’ characteristics (including fraction, average size and distribution), corrosion resistance and hydrogen permeation behaviors in the inter-critically reheated coarse-grained heat-affected zone (ICCGHAZ) of X80 pipeline steel. We observed that the M/A constituents’ characteristics mainly depend on the secondary peak temperature and cooling rates, while the microstructure style and prior austenite grain size are dependent on the first peak temperature. In addition, the variations in the M/A constituents’ characteristics result in different corrosion resistance and hydrogen permeation behaviors by changing the micro-galvanic effect and the number of hydrogen trapping sites. The high fraction and coarse grain size of M/A constituents are against the corrosion resistance and hydrogen permeation in ICCGHAZs, and their functional relationships are established. Moreover, the effects of the fraction of M/A constituents on the corrosion resistance and hydrogen permeation behaviors are much greater than those of the average size.

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Effect of secondary peak temperature on microstructure and toughness in ICCGHAZ of laser-arc hybrid welded X100 pipeline steel joints

Cited by 30 publications

References 32 publications

The effect of heat input in multi-pass GMAW of S960QL UHSS based on weaving and stringer bead procedure on microstructure and mechanical properties of HAZ

The effect of heat input in multi-pass GMAW of S960QL UHSS based on weaving and stringer bead procedure on microstructure and mechanical properties of HAZ

Influence of Vanadium Micro-Alloying on the Microstructure of Structural High Strength Steels Welded Joints

Study on Corrosion Resistance and Hydrogen Permeation Behavior in Inter-Critically Reheated Coarse-Grained Heat-Affected Zone of X80 Pipeline Steel

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