New insights into the mechanism of cooling rate on the impact toughness of coarse grained heat affected zone from the aspect of variant selection

Wang, Xiaolei; Wang, Z.Q.; Dong, Lili; Chen, Shang; Ma, Xiaoping; Subramanian, S.V.

doi:10.1016/j.msea.2017.07.095

Cited by 119 publications

(31 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This trend was also partly observed in previous work in welding of 45-mm thick high strength steel [4]. However, excessively high heat input (< 2.0 kJ/ mm) is proven to be detrimental for HAZ toughness [65] mainly due to very large grains and unfavorable crystallographic features [66,67].…”

Section: Mechanical Test Resultssupporting

confidence: 74%

Laser-arc hybrid welding of 12- and 15-mm thick structural steel

Bunaziv

Dørum

Nielsen

et al. 2020

Int J Adv Manuf Technol

View full text Add to dashboard Cite

High-power lasers are very effective in welding of plates thicker than 10 mm due to the keyhole mode. High-power intensity generates a vapor-filled cavity which provides substantial penetration depth. Due to the narrow and deep weld geometry, there is susceptibility to high hardness and weld defects. Imperfections occur due to keyhole instability. A 16-kW disk laser was used for single-pass welding of 12-to 15-mm thick plates in a butt joint configuration. Root humping was the main imperfection and persisted within a wide range of process parameters. Added arc source to the laser beam process may cause increased root humping and sagging due to accelerated melt flow. Humping was mitigated by balancing certain arc and other process parameters. It was also found that lower welding speeds (< 1.2 m/min) combined with lower laser beam power (< 13 kW) can be more positive for suppression of humping. Machined edges provided more consistent root quality and integrity compared with plasma cut welded specimens. Higher heat input (> 0.80 kJ/mm) welds provided hardness level below 325 HV. The welded joints had good Charpy toughness at − 50°C (> 50 J) and high tensile strength.

show abstract

Section: Mechanical Test Resultssupporting

confidence: 74%

Laser-arc hybrid welding of 12- and 15-mm thick structural steel

Bunaziv

Dørum

Nielsen

et al. 2020

Int J Adv Manuf Technol

View full text Add to dashboard Cite

show abstract

“…Meanwhile, some M-A constituents were decomposed into small parts (the circle in Figure 10a). The TEM photographs of the FP2 of sample JT-5 showed retained austenite, which was formed during tempering [28] (Figure 10b). Thus, the heating temperature was at the tempering range.…”

Section: Microstructurementioning

confidence: 99%

Microstructural Changes and Impact Toughness of Fill Pass in X80 Steel Weld Metal

Bai

Ding

Tong

et al. 2019

Metals

View full text Add to dashboard Cite

Multi-pass welding is used in high-pressure and thick-walled pipes in natural gas and oil pipelines. When a welding layer of a welded joint is subjected to different welding thermal cycles, its microstructure and properties change, thereby affecting the overall welding performance. In this study, the temperature and microstructural variations of the fill pass 2 (FP2) in the entire welding process were investigated by combining the thermal cycle with the cascade welding method. The original FP2 and FP2 after double thermal cycles had the worse deformation ability by tensile test. The toughness of FP2 improved after a single thermal cycle, decreased after double thermal cycles, and improved again after triple thermal cycles. The content of martensite–austenite (M–A) constituents and the average grain size of FP2 in the cascade samples were inversely proportional to FP2 toughness. Massive M–A constituents and their unique distribution at the inter-critical temperature were harmful to weld metal toughness. Controlling the size and fraction of M–A constituents can improve weld metal toughness.

show abstract

“…[ 26,27 ] The toughness depends both on fine grain size and in particular the crystallographic characteristics of different microstructures, such as ferrite, martensite, bainite, tempered martensite, and tempered bainite. [ 28–33 ] There is a continuing debate on the effective control unit for hindering the crack propagation in different phases. Moreover, it is meaningful to study the synergistic effect of microstructural characteristics and nanoscale precipitates on the combination of strength, ductility, and toughness of HSLA steels.…”

Section: Introductionmentioning

confidence: 99%

Significant Improvement in Strength and Toughness of Nanoscale Precipitate–Strengthened Steel by Direct Quenching and Tempering Process

Liu

et al. 2020

steel research int.

View full text Add to dashboard Cite

Herein, the microstructural evolution and mechanical properties of a low‐carbon Nb–Ti–Mo‐bearing steel subjected to hot rolling followed by four different processing schedules (air cooling, direct quenching, low‐temperature tempering, and high‐temperature tempering) are studied to elucidate the significance of structural refinement and nanoscale precipitates for obtaining the optimized combination of strength and toughness. The microstructure of air‐cooled steel composed of coarse polygonal ferrite and granular bainite, and minimum yield strength of 473 MPa and lowest impact energy at −40 °C of 40 J are obtained. The microstructure of steel direct quenched and tempered at 520 °C consists of sub‐micron tempered martensitic and bainitic laths with a high relative fraction of high misorientation boundaries and high density of 3–5 nm (Nb, Ti, Mo)C precipitates, and maximum yield strength of 726 MPa and highest impact energy at −40 °C of 213 J are obtained. The formation of nanoscale precipitates coupled with fine tempered martensitic and bainitic blocks contributes to 253 MPa improvement of yield strength and more than five times enhancement of impact energy. The small blocks of tempered martensite and bainite can deviate and finally arrest the crack propagation, whereas the coarse polygonal ferrite and bainite provide inadequate resistance for crack propagation.

show abstract

New insights into the mechanism of cooling rate on the impact toughness of coarse grained heat affected zone from the aspect of variant selection

Cited by 119 publications

References 27 publications

Laser-arc hybrid welding of 12- and 15-mm thick structural steel

Laser-arc hybrid welding of 12- and 15-mm thick structural steel

Microstructural Changes and Impact Toughness of Fill Pass in X80 Steel Weld Metal

Significant Improvement in Strength and Toughness of Nanoscale Precipitate–Strengthened Steel by Direct Quenching and Tempering Process

Contact Info

Product

Resources

About