Design and Development of Complex Phase Steels with Improved Combination of Strength and Stretch-Flangeability

Graux, Alexis; Cazottes, Sophie; Castro, David; San-Martín, David; Capdevila, Carlos; Cabrera, J.M.; Molas, Sílvia; Schreiber, Sebastian J.; Mirković, Djordje; Danoix, F.; Fabrègue, Damien; Perez, Michel

doi:10.3390/met10060824

Cited by 10 publications

(4 citation statements)

References 34 publications

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“…The globular structure might therefore be granular bainite, which forms at these elevated temperatures for comparable materials. [ 40 ] However, due to the high process‐specific cooling rates, other constituents like a softer martensite that is formed upon the final cooling of the entire part cannot be ruled out. Reducing the VED shifts the underlying transformation mechanisms toward higher part heights and delays the onset of the isothermal transformation.…”

Section: Resultsmentioning

confidence: 99%

Effect of Volumetric Energy Density and Part Height on the Material Properties of Low‐Alloyed Steels Manufactured by Laser‐Based Powder Bed Fusion of Metals

Bartels,

Novotny,

Albert

et al. 2023

Adv Eng Mater

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The layer‐by‐layer manufacturing approach in laser powder bed fusion of metals (PBF‐LB/M) leads to heat accumulation in the workpiece with increasing part heights. The effect of this heat accumulation on the resulting material properties has, however, only barely been studied for low‐alloyed steels. The goal of this work is to analyze the influence of different PBF‐LB/M‐specific boundary conditions like varying part heights and volumetric energy densities (VED) on the resulting material properties. It isfound that lower part regions possess similar hardness (380–410 HV1) and retained austenite values (7%–8%), independent of the applied VED. Higher energy inputs lead to higher retained austenite contents of up to 20% due to an incomplete transformation upon cooling. This rise in retained austenite content is also linked to a decreased material hardness down to 320 HV1. In higher part regions, this effect is reversed as the retained austenite content starts to decrease for the highest investigated VED. This is caused by the in situ preheating temperatures caused by heat accumulation, which favor a bainitic transformation. The part height‐specific properties indicate that the microstructure formation forms through a continuous transformation in lower part regions and through an isothermal transformation in higher regions.

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Section: Resultsmentioning

confidence: 99%

Effect of Volumetric Energy Density and Part Height on the Material Properties of Low‐Alloyed Steels Manufactured by Laser‐Based Powder Bed Fusion of Metals

Bartels,

Novotny,

Albert

et al. 2023

Adv Eng Mater

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“…The transition from a discontinuous to continuous yield point is a common finding in similar steels in the literature, even if bainitic microstructures are involved. Graux et al [20] studied a steel with 0.06% C, 1.9% Mn, 0.5% Si, 0.1% Ti, 0.04% Nb, 0.2% Mo, 0.03% Cr, 0.05% Al, 0.005% N where granular bainite is found at relatively small cooling rates, approximately less than 5°C/s. It is associated to mixed microstructures where ferrite is formed at higher temperature and the untransformed austenite is enriched in carbon.…”

Section: Discussionmentioning

confidence: 99%

Effect of coiling temperature on the structure and properties of thermo-mechanically rolled S700MC steel

Oktay

Nunzio

Cesile

et al. 2022

J min metall B Metall

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Boron-free S700MC steel is usually produced exploiting the properties of a ferrite-bainite mixed microstructure formed by coiling the strips at a temperature of about 450?C, namely below the bainite start temperature. Aiming at further enhancing the mechanical properties for 6 to 10 mm thick strips, industrial trials with a coiling temperature of 600?C have been carried out to promote the formation of a structure of ferrite and carbides, which is also acceptable for this steel grade. Unexpectedly, a microstructure composed of ferrite and martensite has been obtained. Compared with the ferritic-bainitic grade, the new structure is characterized by a slight decrease of the yield point but by an increase of the ultimate tensile strength of not less than 80 MPa, with a transition from a quasi-discontinuous to a clearly continuous yielding behaviour. Accordingly, the yield-to-tensile strength ratio decreases from 0.90 to 0.75 and the impact energy decreases of 35 J and 60 J for the two gauge levels, respectively. The mechanical behaviour of the strips coiled at high temperature is explained as a direct consequence of the dual phase structure with hard phase interspersed in a soft ferrite matrix. The presence of martensite is justified by invoking the so-called incomplete bainite reaction. The partial transformation in ferrite after coiling and the long time necessary for the coil to cool down stabilize the not yet transformed austenite due to the carbon enrichment making the bainite formation impossible at lower temperatures.

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“…Due to their homogeneous microstructure, CP steels exhibit superior stretch-flangeability [70]. Graux et al [71] investigated the effect of process parameters on final mechanical properties and microstructure. The microstructure of hot-rolled bainitic steel obtained consisted of a homogeneous lath/granular bainite mixture and exhibited a hole expansion ratio exceeding 70% and a UTS of 830 MPa.…”

Section: Complex-phase Steelsmentioning

confidence: 99%

Current Trends in Metallic Materials for Body Panels and Structural Members Used in the Automotive Industry

Trzepieciński,

Najm

2024

Materials

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The development of lightweight and durable materials for car body panels and load-bearing elements in the automotive industry results from the constant desire to reduce fuel consumption without reducing vehicle performance. The investigations mainly concern the use of these alloys in the automotive industry, which is characterised by mass production series. Increasing the share of lightweight metals in the entire structure is part of the effort to reduce fuel consumption and carbon dioxide emissions into the atmosphere. Taking into account environmental sustainability aspects, metal sheets are easier to recycle than composite materials. At the same time, the last decade has seen an increase in work related to the plastic forming of sheets made of non-ferrous metal alloys. This article provides an up-to-date systematic overview of the basic applications of metallic materials in the automotive industry. The article focuses on the four largest groups of metallic materials: steels, aluminium alloys, titanium alloys, and magnesium alloys. The work draws attention to the limitations in the development of individual material groups and potential development trends of materials used for car body panels and other structural components.

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Design and Development of Complex Phase Steels with Improved Combination of Strength and Stretch-Flangeability

Cited by 10 publications

References 34 publications

Effect of Volumetric Energy Density and Part Height on the Material Properties of Low‐Alloyed Steels Manufactured by Laser‐Based Powder Bed Fusion of Metals

Effect of Volumetric Energy Density and Part Height on the Material Properties of Low‐Alloyed Steels Manufactured by Laser‐Based Powder Bed Fusion of Metals

Effect of coiling temperature on the structure and properties of thermo-mechanically rolled S700MC steel

Current Trends in Metallic Materials for Body Panels and Structural Members Used in the Automotive Industry

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