Investigations on the thermal behavior of ultra high strength boron manganese steels within hot stamping

Merklein, Marion; Lechler, J.; Stoehr, T.

doi:10.1007/s12289-009-0505-x

Cited by 96 publications

(32 citation statements)

References 3 publications

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Section: Introductionsupporting

confidence: 92%

“…Turetta [5] plotted 22MnB5 steel cooling curves and demonstrated that the higher the contact pressure the higher the cooling rate is. Similar results were reported by several authors [11][12][13][14][15].It has been observed that most of the experimental apparatus and industrial processes operate with closure pressures higher than 10MPa. In this study, a die quenching experimental method, using low closing pressures and an aluminum flat die, was developed in order to simulate characteristic events of the hot stamping process.…”

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An Experimental Method to Simulate the Hot Stamping Process

Olah¹,

Verran²,

Dutra³

2017

Tecnol. Metal. Mater. Min.

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In this study a new experimental method using low closing pressure and a flat aluminum die was developed in order to investigate the hot stamping process of a 22MnB5 steel grade. Initially, an experimental set up was developed and validated. Next, experiments were carried out to evaluate the behavior of this steel when subjected to quenching, using this experimental set up and different cooling conditions such as water, oil and air. Results were assessed by cooling curves, as well as by mechanical tests and metallographic analyzes. Cooling rates close to 110 o C/s, hardness up to 480HV and ultimate tensile strength up to 1600 MPa were achieved, which are considered acceptable values for this steel in normal conditions of hot stamping. Keywords: Hot stamping; 22MnB5 steel; Quenching; Cooling rate. UM MÉTODO EXPERIMENTAL PARA SIMULAR O PROCESSO DE ESTAMPAGEM A QUENTE ResumoNesta pesquisa foi desenvolvido um novo método experimental, utilizando baixa pressão de fechamento e uma matriz plana de alumínio, com o objetivo de investigar o processo de estampagem a quente do aço 22MnB5. Inicialmente um aparato experimental foi desenvolvido e validado. A seguir foram realizados experimentos com o objetivo de avaliar o comportamento deste aço quando submetido a diferentes meios de têmpera, usando este método e diferentes condições de resfriamento, tais como água, óleo e ar. Os resultados foram avaliados usando curvas de resfriamento, bem como ensaios mecânicos e análises metalográficas. Foram obtidas taxas de resfriamento próximas de 100 0 C/s, durezas acima de 480HV e limite de resistência acima de 1600 MPa, valores que são considerados aceitáveis para este aço em condições normais de estampagem a quente. Palavras-chave: Estampagem a quente; Aço 22MnB5; Têmpera; Taxa de resfriamento. INTRODUCTIONIn recent years the hot stamping process has been widely studied, generating significant technological advancement and allowing its use in the production of several components with excellent performance due to the combination of high mechanical properties with high dimensional accuracies.An important aspect in the hot stamping process is that sheet conformation occurs at elevated temperatures, where the mechanical strength of the material is significantly reduced. Thus, the load required to deform the sheet is very low, opening up the possibility of the use of less robust and cheaper equipment, which results in lower operating costs and investment. The stamping tools would also be less stiff and cheaper. The use of low stress for deformation also requires the evaluation of the thermal behavior because the material is hot formed and simultaneously quenched to room temperature, in order to obtain a component with good dimensional accuracy and high mechanical resistance [1]. The conditions involving contact between the tool and the blank and the closing pressure have a significant influence on the heat extraction coefficient, on the cooling rate and consequently, on the final properties of the component. In hot stamping the co...

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Section: Introductionsupporting

confidence: 92%

supporting

confidence: 90%

An Experimental Method to Simulate the Hot Stamping Process

Olah¹,

Verran²,

Dutra³

2017

Tecnol. Metal. Mater. Min.

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“…Hot stamping can be used to produce the components with distributed microstructure and mechanical properties by using the slow cooling rate for the special region in hot stamping [12]. Local reductions of cooling rate can be achieved by using the thin air gap between the tools and the blank [13], controlling the temperature of tools [14], or using the steel with the lower thermal conductivity in the tools [15].…”

Section: List Of Symbols Kmentioning

confidence: 99%

Solution of boundary heat transfer coefficients between hot stamping die and cooling water based on FEM and optimization method

Lin

Zhang

et al. 2015

Heat Mass Transfer

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“…Subsequently, the formed components can be artificially aged to obtain maximum strength [6]. As the HFQ process is a non-isothermal process, and a high friction coefficient is typically observed at elevated temperatures [7], the thermal and tribological properties at the tool/work-piece interface significantly affect formability in the forming process [8][9].…”

Section: Introductionmentioning

confidence: 99%

A study on the buckling behaviour of aluminium alloy sheet in deep drawing with macro-textured blankholder

Zheng

Politis

Lin

et al. 2016

International Journal of Mechanical Sciences

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In this paper an experimental, numerical and analytical investigation is presented of the wrinkling behaviour that occurs in the flange of deep drawn cylindrical cups of aluminium alloy sheet using macro-textured blankholder surfaces. A series of deep drawing experiments were performed using a range of tool textures, draw ratios and blank-holding forces. A numerical material and process model was formulated to enable the occurrence of wrinkling to be simulated. In addition, two analytical buckling models of aluminium alloy sheet in deep drawing with macro-textured blankholder based on the energy method, (namely a one-dimensional and two-dimensional model) were developed for the first-time and utilised to predict the effect of process parameters on wrinkling.The analytical buckling models investigated two boundary conditions, hinged and built-in boundary condition. It was found that texture geometry and draw ratio had a significant effect on wrinkling but the blank-holding force did not. The analytical models developed in this paper to represent sheet metal wrinkling behaviour for the macro-textured tools can be used as a design guide to determine the geometry of tool textures necessary to avoid wrinkling defects in aluminium alloy stamping processes.

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Investigations on the thermal behavior of ultra high strength boron manganese steels within hot stamping

Cited by 96 publications

References 3 publications

An Experimental Method to Simulate the Hot Stamping Process

An Experimental Method to Simulate the Hot Stamping Process

Solution of boundary heat transfer coefficients between hot stamping die and cooling water based on FEM and optimization method

A study on the buckling behaviour of aluminium alloy sheet in deep drawing with macro-textured blankholder

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