Investigating local strain rate sensitivity of the individual weld zone in the friction stir welded DP 780 steel

Han, Seung-Chang; Chaudry, Umer Masood; Yoon, Jinyoung; Jun, Tea‐Sung

doi:10.1016/j.jmrt.2022.07.125

Cited by 13 publications

(3 citation statements)

References 37 publications

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“…During the manufacturing processes of aerospace structures, all types of materials require welding and joining at the highest quality possible. Friction stir welding (FSW) has been proven to satisfy the required quality of welding different types of materials, especially those with low-softening-temperature alloys [15][16][17][18][19][20], and is relatively applied in high-softening-temperature materials such as titanium alloys [21][22][23][24][25] and steel alloys [26][27][28][29][30][31][32][33][34][35]. This is mainly because the available tool materials can be used satisfactorily to produce very long-distance joints without any significant degradation [36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Friction Stir Welding of Aluminum in the Aerospace Industry: The Current Progress and State-of-the-Art Review

et al. 2023

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The use of the friction stir welding (FSW) process as a relatively new solid-state welding technology in the aerospace industry has pushed forward several developments in different related aspects of this strategic industry. In terms of the FSW process itself, due to the geometric limitations involved in the conventional FSW process, many variants have been required over time to suit the different types of geometries and structures, which has resulted in the development of numerous variants such as refill friction stir spot welding (RFSSW), stationary shoulder friction stir welding (SSFSW), and bobbin tool friction stir welding (BTFSW). In terms of FSW machines, significant development has occurred in the new design and adaptation of the existing machining equipment through the use of their structures or the new and specially designed FSW heads. In terms of the most used materials in the aerospace industry, there has been development of new high strength-to-weight ratios such as the 3rd generation aluminum–lithium alloys that have become successfully weldable by FSW with fewer welding defects and a significant improvement in the weld quality and geometric accuracy. The purpose of this article is to summarize the state of knowledge regarding the application of the FSW process to join materials used in the aerospace industry and to identify gaps in the state of the art. This work describes the fundamental techniques and tools necessary to make soundly welded joints. Typical applications of FSW processes are surveyed, including friction stir spot welding, RFSSW, SSFSW, BTFSW, and underwater FSW. Conclusions and suggestions for future development are proposed.

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Section: Introductionmentioning

confidence: 99%

Friction Stir Welding of Aluminum in the Aerospace Industry: The Current Progress and State-of-the-Art Review

et al. 2023

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“…Frómeta et al [7] found that DP steel with a larger volume fraction of ferrite and homogeneously distributed martensite islands exhibited significantly higher crack propagation resistance. Han et al [8] investigated the mechanical properties, microstructural characteristics and the strain rate sensitivity of friction stir welded DP780 steel with different welding speed. Wang et al [9] studied the effect of heat inputs on microstructure and fracture behavior of laser welded joints of DP steels, the results showed that the microstructure of welded joints was similar, while the martensite decomposition and carbide precipitation gradually became significant with the increase of heat input, leading to the hardness decrease of the welded joint.…”

Section: Introductionmentioning

confidence: 99%

“…The martensite content is approximately 56% calculated by Image-Pro software. Ferrite provides a certain plasticity for dual-phase steel, while martensite ensures the strength[8].…”

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confidence: 99%

Microstructure, mechanical properties and tear toughness of laser-welded DP980 dual phase steel

Huang

Ren

et al. 2022

Mater. Res. Express

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In this study, DP980 steel sheets were laser welded with a laser power of 4.5 kW and a welding speed of 4.5 m/min. The microstructural evolution and mechanical properties of the welded joint and the effect of notch location on tear toughness were evaluated. Results show that the fusion zone (FZ) was composed of lath martensite, the hardness (276 HV) of the heat-affected zone (HAZ) was lower than that of the base metal (305 HV) resulting from martensite tempering. The welded specimens failed at the soft HAZ with a 98.4% joint efficiency during the tensile test, and the ultimate tensile strength of the as-recieved steel and welded joint was 1026 MPa and 1010 MPa, respectively. The tear energy of the FZ and HAZ was lower than DP980 base metal (BM). Thus, it is considered that the fracture toughness of the joint decreased after welding. The crack growth path of the FZ gradually deviated toward the HAZ during tearing due to the asymmetrical plastic zone at the crack tip. Compared with the ductile fracture of the base metal, the significant decrease in the fracture toughness of the welded joint is due to the weak deformation resistance of tempered martensite.

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Comparative Study of Room and Cryogenic Deformation Behavior of Additive Manufactured Ti–6Al–4V Alloy

Chaudry,

Noh,

Lee

et al. 2024

Adv Eng Mater

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The microstructural evolution and underlaying deformation behavior of Ti–6Al–4V alloy fabricated by laser powder bed fusion (LPBF‐Ti64) during room (RT) and cryogenic (CT: −150 °C) temperature are systematically investigated. LPBF‐Ti64 exhibits significantly higher strength at CT (yield strength [YS]: 1339 MPa, ultimate compressive strength [UCS]: 1982 MPa) as compared to RT (YS: 1013 MPa, UCS: 1690 MPa) with reduction in fracture strain. To probe the deformation mechanisms responsible for exceptionally higher strength at CT, LPBF‐Ti64 alloy is compressed to 10% strain at both temperatures and the underlaying strengthening mechanisms are investigated. Dislocation strengthening is emphasized to be the major strengthening mechanisms (1166/1359 MPa for RT‐10 and CT‐10, respectively). The significantly higher dislocation density at CT (3.73 1016 m−2 for CT‐10 and 2.9 1016 m−2 for RT‐10) is attributed to the restricted dislocation movement at low temperature, whereas dislocation nucleation during further deformation will multiply the dislocations interlocking and pinning, hence resulting in higher strength.

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Investigating local strain rate sensitivity of the individual weld zone in the friction stir welded DP 780 steel

Cited by 13 publications

References 37 publications

Friction Stir Welding of Aluminum in the Aerospace Industry: The Current Progress and State-of-the-Art Review

Friction Stir Welding of Aluminum in the Aerospace Industry: The Current Progress and State-of-the-Art Review

Microstructure, mechanical properties and tear toughness of laser-welded DP980 dual phase steel

Comparative Study of Room and Cryogenic Deformation Behavior of Additive Manufactured Ti–6Al–4V Alloy

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