Effect of YAG Laser Cutting on Stretch-flangeability of Ultra High Strength TRIP Sheet Steel with Bainitic Ferrite Matrix

Nagasaka, Akihiko; Kubota, Yuichi; Sugimoto, Koh Ichi; Mio, Atsushi; Hojo, Tomohiko; Makii, Koichi; Kawajiri, Masahiro; Kitayama, Mitsunari

doi:10.2355/isijinternational.50.1441

Cited by 20 publications

(17 citation statements)

References 4 publications

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“…However, increasing tensile strength over 980 MPa in the steels decreases not only press formabilities but also impact, fatigue properties and delayed fracture resistance. It is expected that the application of ultrahigh-strength low alloy transformation-induced plasticity (TRIP) 1) -aided steels with bainitic ferrite matrix (TBF steels) [2][3][4][5] will solve these problems. Moreover, TRIP-aided martensitic (TM) steels, [6][7][8][9] and TRIP-aided bainitic ferrite-martensite (TBM) steels 10,11) have been developed to improve the tensile strength in comparison with TBF steels.…”

Section: Introductionmentioning

confidence: 99%

Effects of Matrix Structure and Nitrogen Content on Fatigue Properties of Ultrahigh-Strength Low Alloy TRIP-Aided Steels

et al. 2021

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To develop ultrahigh-strength steels for automotive impact safety parts, the effects of the microstructure and nitrogen content on the fatigue properties of ultrahigh-strength low alloy transformation-induced plasticity (TRIP)-aided steels with martensite (TM), bainitic ferrite-martensite (TBM), and bainitic ferrite (TBF) matrices were investigated. Compared to TBF steels, both the TM and TBM steels achieved high tensile strength, of more than 980 MPa, and excellent fatigue properties. This results from the suppression of crack propagation due to the effective TRIP of the relatively stable interlath retained austenite and the increase in tensile and yield strengths attributed to the low isothermal transformation treatment. The fatigue strengths of the ultrahigh-strength low alloy TRIP-aided steels were slightly increased by the addition of 100 ppm of nitrogen. The increase in fatigue strength of TM, TBM, and TBF steels with 100 ppm of nitrogen was caused by the fine and uniform martensite and bainitic ferrite matrices and retained austenite, along with the increase in carbon concentration in the retained austenite due to the precipitation of AlN.

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Section: Introductionmentioning

confidence: 99%

Effects of Matrix Structure and Nitrogen Content on Fatigue Properties of Ultrahigh-Strength Low Alloy TRIP-Aided Steels

et al. 2021

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“…On the other hand, in the view point of the press formability of the TRIP-aided steel with bainitic ferrite matrix (TBF steel), it has been reported that the stretch-flangeability of the TBF steels was superior to that of the TDP steels. 7) However, since the TS × TEl and the volume fraction of γ R of the TBF steels are relatively low, the transformation of γ R of by scanning electron microscope-electron backscatter diffraction (SEM-EBSD) analysis is not detectable. Thus, it is difficult to clarify the mechanism of the superior stretchflangeability of the TBF steels.…”

Section: Introductionmentioning

confidence: 99%

Effect of Carbon Content on V-Bending in High-Strength TRIP-Aided Dual-Phase Steel Sheets with Polygonal Ferrite Matrix

et al. 2021

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Effect of carbon content on V-bending in high-strength TRIP-aided dual-phase (TDP) steel sheets with polygonal ferrite matrix was investigated for automobile applications. V-bending test was performed on a hydraulic testing machine at a processing speed of 1 mm/min, using a rectangular specimen (50 mm in length, 5 mm in width, 1.2 mm in thickness). The main results are as follows. (1) The (0.1-0.4)C-1.5Si-1.5Mn, mass% TDP steel sheets were able to perform V-bending by straininduced martensitic transformation of TRIP effect. On the other hand, ferrite-martensite dual-phase (MDP0) steel sheet of 900 MPa grade was not able to perform 90-degree V-bending because of initiation of crack in tension region. (2) The 0.4C-1.5Si-1.5Mn, mass% TDP4 steel sheet of 1 100 MPa grade was able to enable the 90-degree V-bending that considered an amount of springback (Δθ = θ 2 − θ 1), in which the θ 1 and the θ 2 are a bending angle on loading and a bending angle after unloading respectively, of more than 2-degree by controlling a displacement of punch bottom dead center.

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“…In recent years, 1 470 MPa grade hot stamping members have been widely used for pillars and bumper beams for the purpose of the weight reduction and the improvement of crash safety. 1) In addition, although there have been some research on the springback-free and the servo press of V-bending, [2][3][4] the studies on the V-bending of the TRansformation-Induced Plasticity (TRIP 5) ) steel sheets have not been sufficiently conducted, 3) whereas TRIP steel sheets can be expected to be applied 6,7) for automotive structural parts, considering the crash safety and the press formability.…”

Section: Introductionmentioning

confidence: 99%

Effects of Silicon and Manganese Contents on V-Bending in High-Strength TRIP-Aided Dual-Phase Steel Sheets with Polygonal Ferrite Matrix

et al. 2021

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Effects of silicon and manganese contents on V-bending in high-strength TRIP-aided dual-phase (TDP) steel sheets with polygonal ferrite matrix were investigated for automotive applications. V-bending test was performed on a hydraulic testing machine at a processing speed of 1 mm/min, using a rectangular specimen (50 mm in length, 5 mm in width, 1.2 mm in thickness), 88-degree punch (2.0 mm in punch radius), and 88-degree die (12 mm in die width, 0.8 mm in die radius). The main results are as follows.(1) The 0.2C-(1.0-2.5)Si-(1.0-2.0)Mn, mass% TDP steel sheets were able to perform V-bending by straininduced martensitic transformation of TRIP effect. On the other hand, ferrite-martensite dual-phase (MDP0) steel sheet of 900 MPa grade was not able to perform 90-degree V-bending because of initiation of crack on an outer surface.(2) The 0.2C-2.5Si-1.5Mn, mass% TDP-G steel sheet of 980 MPa grade was able to enable the 90-degree V-bending that considered an amount of springback (Δθ = θ 1 − θ 2 ), in which the θ 1 and the θ 2 are a bending angle on loading and a bending angle after unloading respectively, of more than 2-degree by controlling a displacement of punch bottom dead center.

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Effect of YAG Laser Cutting on Stretch-flangeability of Ultra High Strength TRIP Sheet Steel with Bainitic Ferrite Matrix

Cited by 20 publications

References 4 publications

Effects of Matrix Structure and Nitrogen Content on Fatigue Properties of Ultrahigh-Strength Low Alloy TRIP-Aided Steels

Effects of Matrix Structure and Nitrogen Content on Fatigue Properties of Ultrahigh-Strength Low Alloy TRIP-Aided Steels

Effect of Carbon Content on V-Bending in High-Strength TRIP-Aided Dual-Phase Steel Sheets with Polygonal Ferrite Matrix

Effects of Silicon and Manganese Contents on V-Bending in High-Strength TRIP-Aided Dual-Phase Steel Sheets with Polygonal Ferrite Matrix

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