Shielding gas influences on laser weldability of tailored blanks of advanced automotive steels

Reisgen, Uwe; Schleser, Markus; Mokrov, Oleg; Ahmed, Essam

doi:10.1016/j.apsusc.2010.08.042

Cited by 33 publications

(19 citation statements)

References 13 publications

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“…As a result that the welding speed increases, the line energy decreases, which leads to the width and penetration decrease. It is in agreement with the numerical result by Vrtiel [23], and they found that under 2000 W laser power, a full penetration of 2 mm laser welded joint of high-strength TRIP steel cannot be ensured when the welding velocity is higher than 90 mm s −1 .…”

Section: Relationship Of the Welding Seam Size With The Welding Speedsupporting

confidence: 91%

Microstructure and tensile properties of the different thickness ASSAPH440 high strength steel/DC52D+ZF45 galvanized cold rolled sheet dissimilar metal welding joint by CO₂ laser welding for automobile manufacturing

Luo

Gao

Lin

et al. 2020

Mater. Res. Express

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In order to adapt to the development trend of a lightweight automobile and meet the safety requirements of key automotive parts, it is necessary to study the relationship between microstructure and mechanical properties of the dissimilar and different thickness materials welded joint. In this work, a dissimilar welded joint of high strength vehicle steel ASSAPH440 with 2.0 mm thickness/ galvanized cold rolled sheet DC52D+ZF45 with 2.6 mm thickness formed by CO 2 laser welding was studied. The microstructure of the welded joint was analyzed by metallographic structure and mechanical properties were discussed in terms of their tensile strength and microhardness. The results indicated that a high-quality welded joint with an average tensile strength of 643 MPa and an elongation of 22.7% was obtained at a welding speed of 30 mm s −1 and the laser power of 2200 w in CO 2 laser welding, the tensile strength of laser welded joint was more than that of the both based metals. The center of the welding seam was composed of slender lath martensite with a few small white pieces of ferrite. The microstructure of the Heat Affected Zone (HAZ) on the DC52D+ZF45 side was smaller than that of the HAZ on the ASSAPH440 side, and its mechanical properties were superior. The highest microhardness was obtained at the center of the cross section of the welding seam, and the microhardness of the welding seam on the DC52D+ZF45 side was higher than that of the welding seam on the ASSAPH440 side. The tensile fracture appeared at the base metal of DC52D+ZF45 steel as a result of the strength of ASSAPH440 was more than that of DC52D+ZF45. The performance of the laser welded joint met the technical requirements of automobile manufacturing engineering. manufacturing of the entire body of an automobile in Europe, the United States and Japan [5][6][7]. Currently, structural body parts made from ordinary steel plates are being replaced by high-strength steel plates. The highstrength steel sheets for vehicles generally have a tensile strength above 350 MPa. It not only has high tensile strength but also high yield strength, high weight loss potential, high impact absorption energy, high formability and low planar anisotropy.However, laser welding of high-strength steel is difficult because of the complicated metal state in the process of laser welding. Under the condition of the extremely fast heating and cooling speed during the laser welding, a large amount of non-equilibrium structure will appear in HAZ of welded joint, which hurts softening behavior of the welded joints [8][9][10]. Xia [11] studied the laser welded joints of high-strength steel with a tensile strength ranging from 450∼980 Mpa. They found that all joints existed the softening zones, and the degree of softening is related to the volume of martensite. As the heat input increases, the content of martensite in the softening zone decreases and the degree of softening increases. Consequently, the tensile strength of the welded joint was reduced. Sreenivasan [12] found that the forma...

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Section: Relationship Of the Welding Seam Size With The Welding Speedsupporting

confidence: 91%

Microstructure and tensile properties of the different thickness ASSAPH440 high strength steel/DC52D+ZF45 galvanized cold rolled sheet dissimilar metal welding joint by CO₂ laser welding for automobile manufacturing

Luo

Gao

Lin

et al. 2020

Mater. Res. Express

View full text Add to dashboard Cite

show abstract

“…This difference was due to the tendency of the shielding gas to form plasma. The shielding gas with a lower molecular weight, higher thermal conductivity, and higher ionization energy generated less plasma [22]. With respect to argon, nitrogen was more effective to suppress the plasma and stabilize the keyhole.…”

Section: Porosity Mitigationmentioning

confidence: 99%

Hybrid Laser-arc Welding of 17-4 PH Martensitic Stainless Steel

Liu

Atabaki

et al. 2015

Lasers Manuf. Mater. Process.

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17-4 PH stainless steel has wide applications in severe working conditions due to its combination of good corrosion resistance and high strength. The weldability of 17-4 PH stainless steel is challenging. In this work, hybrid laser-arc welding was developed to weld 17-4 PH stainless steel. This method was chosen based on its advantages, such as deep weld penetration, less filler materials, and high welding speed. The 17-4 PH stainless steel plates with a thickness of 19 mm were successfully welded in a single pass. During the hybrid welding, the 17-4 PH stainless steel was immensely susceptible to porosity and solidification cracking. The porosity was avoided by using nitrogen as the shielding gas. The nitrogen stabilized the keyhole and inhibited the formation of bubbles during welding. Solidification cracking easily occurred along the weld centerline at the root of the hybrid laser-arc welds. The microstructural evolution and the cracking susceptibility of 17-4 PH stainless steel were investigated to remove these centerline cracks. The results showed that the solidification mode of the material changed due to high cooling rate at the root of the weld. The rapid cooling rate caused the transformation from ferrite to austenite during the solidification stage. The solidification cracking was likely formed as a result of this cracking-susceptible microstructure and a high depth/width ratio that led to a high tensile stress concentration. Furthermore, the solidification cracking was prevented by preheating the base metal. It was found that the preheating slowed the cooling rate at the root of the weld, and the ferrite-to-austenite transformation during the solidification stage was suppressed. Delta ferrite formation was observed in the weld bead as well no solidification cracking occurred by optimizing the preheating temperature.

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“…Baghjari et al [23] paid attention to the Nd:YAG laser welding of AISI420 martensitic stainless steel as well as the sensitivities of voltage, laser beam diameter, energy frequency, pulse duration, and welding velocity to the size and deformation of the welded joint. However, previous studies [24][25][26][27][28] indicated that the mechanical properties of DP steel butt joint have effects evident in the process operation parameters. This may be due to the soft zone formed in the adjacent heat-affected zone (HAZ).…”

Section: Introductionmentioning

confidence: 99%

Effects of Pulsed Nd:YAG Laser Welding Parameters on Penetration and Microstructure Characterization of a DP1000 Steel Butt Joint

Xue

Péreira

Amorim

et al. 2017

Metals

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Abstract:Of particular importance and interest are the effects of pulsed Nd:YAG laser beam welding parameters on penetration and microstructure characterization of DP1000 butt joint, which is widely used in the automotive industry nowadays. Some key experimental technologies including pre-welding sample preparation and optimization design of sample fixture for a sufficient shielding gas flow are performed to ensure consistent and stable testing. The weld quality can be influenced by several process factors, such as laser beam power, pulse duration, overlap, spot diameter, pulse type, and welding velocity. The results indicate that these key process parameters have a significant effect on the weld penetration. Meanwhile, the fusion zone of butt joints exhibits obviously greater hardness than the base metal and heat affected zone of butt joints. Additionally, the volume fraction of martensite of dual-phase steel plays a considerable effect on the hardness and the change of microstructure characterization of the weld joint.

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Shielding gas influences on laser weldability of tailored blanks of advanced automotive steels

Cited by 33 publications

References 13 publications

Microstructure and tensile properties of the different thickness ASSAPH440 high strength steel/DC52D+ZF45 galvanized cold rolled sheet dissimilar metal welding joint by CO₂ laser welding for automobile manufacturing

Microstructure and tensile properties of the different thickness ASSAPH440 high strength steel/DC52D+ZF45 galvanized cold rolled sheet dissimilar metal welding joint by CO₂ laser welding for automobile manufacturing

Hybrid Laser-arc Welding of 17-4 PH Martensitic Stainless Steel

Effects of Pulsed Nd:YAG Laser Welding Parameters on Penetration and Microstructure Characterization of a DP1000 Steel Butt Joint

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Shielding gas influences on laser weldability of tailored blanks of advanced automotive steels

Cited by 33 publications

References 13 publications

Microstructure and tensile properties of the different thickness ASSAPH440 high strength steel/DC52D+ZF45 galvanized cold rolled sheet dissimilar metal welding joint by CO2 laser welding for automobile manufacturing

Microstructure and tensile properties of the different thickness ASSAPH440 high strength steel/DC52D+ZF45 galvanized cold rolled sheet dissimilar metal welding joint by CO2 laser welding for automobile manufacturing

Hybrid Laser-arc Welding of 17-4 PH Martensitic Stainless Steel

Effects of Pulsed Nd:YAG Laser Welding Parameters on Penetration and Microstructure Characterization of a DP1000 Steel Butt Joint

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Product

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Microstructure and tensile properties of the different thickness ASSAPH440 high strength steel/DC52D+ZF45 galvanized cold rolled sheet dissimilar metal welding joint by CO₂ laser welding for automobile manufacturing

Microstructure and tensile properties of the different thickness ASSAPH440 high strength steel/DC52D+ZF45 galvanized cold rolled sheet dissimilar metal welding joint by CO₂ laser welding for automobile manufacturing