Resistance Spot Welding of Zn-Coated Third Generation Automotive Steels Using Mid-Frequency Direct Current Technology

Başer, Tanya A.

doi:10.1007/s12666-022-02771-7

Cited by 4 publications

(3 citation statements)

References 12 publications

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“…Başer [32], joined galvanized beynitic ferrite-supported TRIP (TBF) steel using direct current medium frequency technology (MFDC) with the RSW method and applied magnetic particle (MP) testing to detect liquid metal embrittlement in the joints. As a result of the magnetic particle testing, it was reported that no liquid metal embrittlement was detected in the weld core and HAZ.…”

Section: Visual Inspection and Magnetic Particle Testingmentioning

confidence: 99%

Regional Pre-Heat Treatment System Development and Applications for HAZ in RSW Joining of High-Strength Steels

Aydın

HIDIROĞLU²,

Kahraman³

2023

Preprint

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STRENX and DP steels are advanced high-strength dual-phase steel types used in the automotive industry for producing lightweight vehicles that have low cost, high fuel efficiency, and can carry more load volume. In this study, STRENX 700 CR and DP 800 steels were joined by resistance spot welding (RSW) using medium frequency direct current (MFDC). Some parts were joined under atmospheric conditions, while others were joined by applying regional pre-heating (RPH) to their heat-affected zones (HAZ) before welding. The design, manufacturing, and adaptation of the RPH system to the RSW machine were carried out as part of this study, considering it as a new system. After the joining process, non-destructive (visual inspection, magnetic particle) and destructive (microhardness, tensile-shear, cross-tension, fatigue) tests were performed on RSW connections between STRENX 700 CR and DP 800 steels. Hardness tests revealed that the RPH applied to the HAZ before welding reduced the hardness of the weld metal by approximately 8%, while the microstructure analysis showed that the RPH increased both the weld metal and the HAZ width. The tensile-shear strength increased by about 7%, and the cross-tension test strength increased by about 5% with the RPH applied to the HAZ before welding. In both the tensile-shear and cross-tension tests, all failures occurred in the form of button shearing from the HAZ. The RPH treated specimens showed the highest fatigue life, with an average of 947,632 cycles.

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Section: Visual Inspection and Magnetic Particle Testingmentioning

confidence: 99%

Regional Pre-Heat Treatment System Development and Applications for HAZ in RSW Joining of High-Strength Steels

Aydın

HIDIROĞLU²,

Kahraman³

2023

Preprint

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“…Cracks and brittle fractures occur during solidification. It is widely known that LME occurance depends on due to various reasons such as liquid Zn, welding parameters, alloy strength as well as thermal history and galvanised coating type [5][6][7][8]. It was observed that steels with tensile strengths higher than 1000 MPa exhibit the highest LME crack sensitivity [8].…”

Section: Introductionmentioning

confidence: 99%

“…It is widely known that LME occurance depends on due to various reasons such as liquid Zn, welding parameters, alloy strength as well as thermal history and galvanised coating type [5][6][7][8]. It was observed that steels with tensile strengths higher than 1000 MPa exhibit the highest LME crack sensitivity [8]. In addition, the type of Zn based coating also play an important role on the LME crack sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Determination of Liquid Metal Embrittlement After Resistance Spot Welding of Zn-Coated High-Strength Steels

HIDIROĞLU,

BAŞER

2023

METAL Conference Proeedings

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The weight reduction of vehicle body and parts become much more crucial to decrease CO2 emissions. The use of high-strength steels has increased within the scope of vehicle weight reduction studies. The corrosion resistance must be also ensured for automotive structural components. Therefore, zinc-coated high strength steels have been developed. Liquid metal embrittlement (LME) occurs during resistance spot welding (RSW) on zinc-coated high strength steels The liquid zinc from the coating penetrates along the grain boundaries in the material, where it leads to surface cracking. In this study, LME formation was investigated on zinc coated high strength steels during resistance spot welding (RSW). The effect of different type of zinc coating on LME formation was also considered. The results show that the type of zinc coating as well as the grade of the steel have considerable effect on LME formation. The maximum LME crack length was measured as 387 µm on GI coated Q&P 1180-Q&P 1180 welded joints by RSW.

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Enhancing weld strength in high-strength steels: the role of regional preheating in RSW

Aydin,

Hıdıroğlu,

Kahraman

2024

Materials Testing

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In this study, automotive in sector use STRENX 700 CR and DP 800 steels were joined by resistance spot welding using medium frequency direct current. Some parts were joined under atmospheric conditions, while others were joined by applying regional preheating to their heat-affected zones before welding. The design, manufacturing, and adaptation of the preheating system to the welding machine were carried out as part of this study, considering it as a new system. After the joining process, nondestructive and destructive tests were performed on resistance spot welding connections between STRENX 700 CR and DP 800 steels. Hardness tests revealed that the preheating applied to the heat-affected zones before welding reduced the hardness of the weld metal by approximately 8 %, while the microstructure analysis showed that the regional preheating increased both the weld metal and the heat-affected zones width. The tensile-shear strength increased by about 7 %, and the cross-tension test strength increased by about 5 % with the preheating applied to the heat-affected zones before welding. In both the tensile-shear and cross-tension tests, all failures occurred in the form of button shearing from the heat-affected zones. The regional preheating treated specimens showed the highest fatigue life, with an average of 947,632 cycles.

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Resistance Spot Welding of Zn-Coated Third Generation Automotive Steels Using Mid-Frequency Direct Current Technology

Cited by 4 publications

References 12 publications

Regional Pre-Heat Treatment System Development and Applications for HAZ in RSW Joining of High-Strength Steels

Regional Pre-Heat Treatment System Development and Applications for HAZ in RSW Joining of High-Strength Steels

Determination of Liquid Metal Embrittlement After Resistance Spot Welding of Zn-Coated High-Strength Steels

Enhancing weld strength in high-strength steels: the role of regional preheating in RSW

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