Influence of heat-treated Al–Si coating on the weldability and microstructural inhomogeneity for hot stamped steel resistance nut projection welds

Chun, Eun−Joon; Lim, Sung-Sang; Kim, Young-Tae; Nam, Ki-Sung; Kim, Young‐Min; Park, Young-Whan; Murugan, Siva Prasad; Park, Yeong-Do

doi:10.1007/s12540-018-0108-5

Cited by 17 publications

(7 citation statements)

References 22 publications

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“…Third generation advanced high strength steels were used in automotive manufacturing owing to their high ductility and fatigue resistance [1][2][3][4][5][6][7][8][9][10][11]. Good corrosion resistance [12] of sheet steel was achieved by galvanizing [6,8,[13][14][15][16] compared to Al-Si coatings. However, the use of Zn-based coatings led to liquid metal embrittlement (LME).…”

Section: Introductionmentioning

confidence: 99%

Liquid Metal Embrittlement Susceptibility of Hot Formed Zn-Al-Mg Coated Steel with Eutectic Coating Microstructure

Yang,

Fu,

et al. 2023

Metals

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Liquid metal embrittlement (LME) in Zn-based coating plates during hot stamping is an abnormal phenomenon where intimate contact between liquid Zn and a steel matrix results in the penetration of liquid Zn into the matrix, causing ruptures. In order to alleviate LME phenomenon, this paper designed a series of eutectic Zn-Al-Mg coating alloys to improve the uniformity of the Zn element distribution in the coating during heat treatment and inhibit the reaction between Fe and Zn. The high temperature mechanical properties of the coated steels are determined using thermal simulation to calculate the relative reduction in fracture energy, which is used to evaluate the LME level of the different composition coatings. It is suggested that the Zn-4.5Al-3.0Mg coating shows the highest LME resistance at 920 °C. The microstructure of these Zn-Al-Mg coated steels is observed after austenitization at 850 °C~920 °C for 3 min, which shows that the uniformity of the microstructure after austenitizing is affected by the composition of the coating and the austenitizing temperature. The higher temperature benefits the homogenization of the coating and steel and inhibits LME. The findings of this study provide valuable insights for the development of ternary Zn based LME resistant coatings.

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Section: Introductionmentioning

confidence: 99%

Liquid Metal Embrittlement Susceptibility of Hot Formed Zn-Al-Mg Coated Steel with Eutectic Coating Microstructure

Yang,

Fu,

et al. 2023

Metals

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“…RSW is an effective welding process with high productivity owing to low cost and short process time. The coating layers affect resistance spot weldability of HPF steels [23][24][25][26][27][28]. In particular, AlSi-c HPF steels have a wide weldable current range due to their low contact resistance and a large current passage through the melting coating layer [23,29].…”

Section: Introductionmentioning

confidence: 99%

Improvement of resistance spot weldability of Al–Fe-alloy-coated HPF steel sheets

Yun

Gwon

et al. 2022

Science and Technology of Welding and Joining

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The resistance spot weldability of Al-Fe-alloy-coated (AlFe-c) HPF steels manufactured by heattreating Al-Si coated (AlSi-c) steel at 650°C for 10 h was investigated. Since AlFe-c steel had thick oxides in surface layer, the transition resistance was higher and weldability was poorer than the conventional AlSi-c steels. During spot welding of AlFe-c steels, expulsion occurred at low current, so the weld could not grow sufficiently. For this reason, AlFe-c steels had no weldable current range. To improve the weldability, pre-pulse current pattern was applied. By removing the oxides in the coating layer during the pre-pulse step, the resistance of the weld part was reduced, and the expulsion was delayed, so the weldable current range of AlFe-c steel was improved.

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“…Compared with conventional steels, AHSS reduces car body sheet thickness, while satisfying the strength and formability requirements. To prevent corrosion, AHSSs are typically coated with zinc (Zn) or aluminium (Al) [2, 3]. Generally, Zn coatings are available in two types: galvanised (GI) and galvannealed (GA).…”

Section: Introductionmentioning

confidence: 99%

Liquid metal embrittlement during the resistance spot welding of galvannealed steels: synergy of liquid Zn, α-Fe(Zn) and tensile stress

Kim

Murugan

Kim

et al. 2021

Science and Technology of Welding and Joining

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In this study, the influence of the microstructural evolution of galvannealed (GA) coating and the thermomechanical characteristics of liquid metal embrittlement (LME) cracking during resistance spot welding (RSW) of steels were investigated. The analysis of LME cracks, coating microstructure and thermomechanical characteristics at various weld regions revealed a synergistic effect of liquid Zn, α-Fe(Zn), and tensile stress on LME cracking during RSW. A continuous α-Fe(Zn) layer inhibits liquid Zn from contacting the steel substrate; hence, LME was suppressed. However, a long-duration, high-magnitude tensile stress can fragment the α-Fe(Zn) layer and enable LME cracking. Conversely, α-Fe(Zn) particles allow the easy infiltration of liquid into the steel and make the crack on tensile stress development.

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Influence of heat-treated Al–Si coating on the weldability and microstructural inhomogeneity for hot stamped steel resistance nut projection welds

Cited by 17 publications

References 22 publications

Liquid Metal Embrittlement Susceptibility of Hot Formed Zn-Al-Mg Coated Steel with Eutectic Coating Microstructure

Liquid Metal Embrittlement Susceptibility of Hot Formed Zn-Al-Mg Coated Steel with Eutectic Coating Microstructure

Improvement of resistance spot weldability of Al–Fe-alloy-coated HPF steel sheets

Liquid metal embrittlement during the resistance spot welding of galvannealed steels: synergy of liquid Zn, α-Fe(Zn) and tensile stress

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