Microstructural features and mechanical properties of 22MnB5 hot stamping steel in different heat treatment conditions

Çavuşoğlu, Onur; Çavuşoğlu, Oktay; Yılmazoğlu, Ahmet Gürkan; Üzel, Uğur; Aydın, Hakan; Güral, Ahmet

doi:10.1016/j.jmrt.2020.07.043

Cited by 47 publications

(27 citation statements)

References 18 publications

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“…These samples were all processed by cryogenic treatment and tempering at 300°C for 20 min. ( B ) Tensile properties of both steels with well-organized martensite (forged alloys A and B) compared with those of other advanced ultrahigh strength steels, including high-strength low-alloy (HSLA) steels ( 33 – 35 ), maraging steels ( 6 , 8 , 36 ), nano-bainite steels ( 37 ), hot-pressing steels ( 38 – 40 ), medium-Mn steels ( 41 – 45 ), equal channel angular pressing (ECAP) or 3D-print steels ( 46 – 48 ), quenched and partitioned (Q&P) steels ( 49 – 51 ), D&P steels ( 11 ), and chemical boundary engineering (CBE) steels ( 12 ).…”

Section: Resultsmentioning

confidence: 99%

Ductile 2-GPa steels with hierarchical substructure

Yuan

et al. 2023

Science

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Mechanically strong and ductile load–carrying materials are needed in all sectors, from transportation to lightweight design to safe infrastructure. Yet, a grand challenge is to unify both features in one material. We show that a plain medium-manganese steel can be processed to have a tensile strength >2.2 gigapascals at a uniform elongation >20%. This requires a combination of multiple transversal forging, cryogenic treatment, and tempering steps. A hierarchical microstructure that consists of laminated and twofold topologically aligned martensite with finely dispersed retained austenite simultaneously activates multiple micromechanisms to strengthen and ductilize the material. The dislocation slip in the well-organized martensite and the gradual deformation-stimulated phase transformation synergistically produce the high ductility. Our nanostructure design strategy produces 2 gigapascal–strength and yet ductile steels that have attractive composition and the potential to be produced at large industrial scales.

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Section: Resultsmentioning

confidence: 99%

Ductile 2-GPa steels with hierarchical substructure

Yuan

et al. 2023

Science

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“…Considering the averages of all the investigated areas, substantially no differences are observed for Al and Si content between the two configurations, registering 0.65% and about 0.40% averaged content of Al and Si, respectively. Assuming the weld seam as a Fe-Cr-Ni alloy, the related ternary alloy phase diagram already proposed in the literature [55] shows that the FZ with the element averaged weight content obtained by SEM-EDS analyses is characterized by a full FCC microstructure (i.e., austenite with no ferrite) at a temperature of 850 °C, i.e., above the Ac3 one [56]. However, the use of a ternary alloy phase diagram could not be exhaustive since it does not take into account the effects of other chemical components, i.e., Al, Si, Mn, and C, which have noticeable effects on the FZ microstructure even in little amounts.…”

Section: Microstructural Evolution Macrographs and Sem-eds Analysismentioning

confidence: 89%

Laser welding of tailored blanks made of Al-Si-coated 22MnB5 steel using a filler wire and a variable energy distribution laser optics

Coviello

Heydt²,

Rullo³

et al. 2023

Int J Adv Manuf Technol

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Laser welding of Al-Si-coated steels for hot stamping in automotive applications is problematic due to the mixing of the coating layers inside the molten pool that weakens the resulting weld seam. In this case, the most common welding procedure to overcome this issue consists in removing the Al-Si layer through laser ablation prior to the joining. This method continues to be the most widely used by major producers of tailor welded blanks, although in situ ablation of the Al-Si coating can be costly and time consuming. In this work, a novel approach consisting in joining as-received (i.e., not decoated) materials using a filler wire and an innovative variable energy distribution laser optics is introduced and tested on tailor welded blanks made of 22MnB5. Tensile tests of specimens obtained from a 33 full factorial design of experiment have shown an average value of ultimate tensile strength of 1523 MPa, which is much higher than the one usually observed in as-received welded then hot-stamped conditions and aligned with hot-stamped base material values. Hardness test results (494–543 HV0.5) were in the typical hot-stamped base material range of values as well, while SEM–EDS analyses detected no ferrite inclusions inside the fusion zone. Variations of the main process parameters have been considered on an iso-thickness and iso-material configuration, empirically demonstrating the stability and reliability of the proposed methodology as well as its suitability for production purposes.

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“…The specimens were obtained from hot rolled steel plate Usibor 1500-AS (22MnB5) with a thickness of 1.5 mm. The sheet is treated on both sides with an aluminium-silicone coating called "Alusi" (Al 90%, Si 10%), which was removed by grinding in further preparation [7,8]. Usibor 1500 was used because of its good reactivity with the etchant and because it fits into our area of interest of AHSS steels.…”

Section: Specimen Fabrication Methodologymentioning

confidence: 99%

Automation of metallographic sample cleaning process

Čermák

Ambrož

Jozefovič

et al. 2022

METAL Conference Proeedings

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Specimen cleaning and drying are critical processes following any metallographic preparation steps. The paper focuses on automation by reason of absence of the process repeatability during manual sample handling. An etchant or electrolyte results in inhomogeneous surface quality because the solution runs off the specimen surface during its removal from the beaker. High-quality specimen cleaning is absolutely crucial for the acquisition of the specimen suitable for characterization by a scanning electron microscope operated at very low landing energies of the primary electrons (SLEEM). The SLEEM technique is a powerful tool for the characterization of advanced steels, as described by many scientific papers. The SLEEM requires the specimen absolutely free of water and any organic residues on the surface. This work presents a novel unique apparatus enabling automatic specimen cleaning and drying after the etching or electropolishing processes. Automation reduces the influence of dependent variables that would be introduced into the process by the metallographer. These variables include cleaning time, kinematics, and motion dynamics, but the process can also be affected by variables that are not obvious. Performed experiments clearly demonstrate our in-house designed apparatus as a useful tool improving efficiency and consistency of the sample cleaning process. The high quality of the specimen surface is verified using a light optical microscope, an electron scanning microscope, and above mentioned SLEEM technique.

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Microstructural features and mechanical properties of 22MnB5 hot stamping steel in different heat treatment conditions

Cited by 47 publications

References 18 publications

Ductile 2-GPa steels with hierarchical substructure

Ductile 2-GPa steels with hierarchical substructure

Laser welding of tailored blanks made of Al-Si-coated 22MnB5 steel using a filler wire and a variable energy distribution laser optics

Automation of metallographic sample cleaning process

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