Effect of strain hardening capability on plastic deformation behaviors of material during metal forming

Eom, Jae-Gun; Son, Y.H.; Jeong, Sang Won; Ahn, Soon-Tae; Jang, S.M.; Yoon, Duk Jae; Joun, Man Soo

doi:10.1016/j.matdes.2013.08.101

Cited by 44 publications

(29 citation statements)

References 20 publications

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“…The strain up to which the flow stress was theoretically obtained was quite large. The technique can predict the flow stress at the strain of around 1.5, depending on the materials [ 33 , 34 , 35 ]. Note that the point marked “necking point” in the true stress-strain curve in Figure 6 corresponds to the actual necking point in Figure 7 .…”

Section: Problem Descriptionmentioning

confidence: 99%

A New Methodology for Predicting Brittle Fracture of Plastically Deformable Materials: Application to a Cold Shell Nosing Process

Eom¹,

Byun²,

Jeong³

et al. 2021

Materials

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The traditional theory of ductile fracture has limitations for predicting crack generation during a cold shell nosing process. Various damage criteria are employed to explain fracture and failure in the nose part of a cold shell. In this study, differences in microstructure among fractured materials and analysis of their surfaces indicated the occurrence of brittle fractures. The degree of “plastic deformation-induced embrittlement” (PDIE) of plastically deformable materials affects the likelihood of brittle fractures; PDIE can also decrease the strength in tension due to the Bauschinger effect. Two indicators of brittle fracture are presented, i.e., the critical value of PDIE and the allowable tensile strength (which in turn depends on the degree of PDIE or embrittlement-effective strain). When the maximum principal stress is greater than the latter and the PDIE is greater than the former, our method determines the likelihood of brittle fracture. This approach was applied to an actual cold shell nosing process, and the predictions were in good quantitative agreement with the experimental results.

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Section: Problem Descriptionmentioning

confidence: 99%

A New Methodology for Predicting Brittle Fracture of Plastically Deformable Materials: Application to a Cold Shell Nosing Process

Eom¹,

Byun²,

Jeong³

et al. 2021

Materials

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“…Plate forging and bulk sheet forming of metal parts, which can replace conventional heavy parts, of electric and/or electronic devices have been ongoing for two decades [1][2][3][4]. Additionally, the forging of high-strength and/or lightweight materials has been intensively researched [5][6][7][8]. New car-friendly materials and applications have emerged.…”

Section: Introductionmentioning

confidence: 99%

“…These have been long-standing difficulties for application engineers and researchers of materials. Applications remain very limited; advances in die materials and lubricants lag behind those in high-strength cold forged SUS and high-strength energy saver wire (ESW) materials [5,7,14]. Stainless steels do not require heat treatment after cold forging, which enhances safety.…”

Section: Introductionmentioning

confidence: 99%

Automatic Multi-Stage Cold Forging of an SUS304 Ball-Stud with a Hexagonal Hole at One End

Byun

Razali

Lee³

et al. 2020

Materials

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SUS304 stainless steel is characterized by combined tensile and compression testing, with an emphasis on flow stress at higher strain and temperature. The plastic deformation behavior of SUS304 from room temperature to 400 °C is examined and a general approach is used to express flow stress as a closed-form function of strain, strain rate, and temperature; this is optimal when the strain is high, especially during automatic multi-stage cold forging. The fitted flow stress is subjected to elastothermoviscoplastic finite element analysis (FEA) of an automatic multi-stage cold forging process for an SUS304 ball-stud. The importance of the thermal effect during cold forging, in terms of high material strength and good strain-hardening, is revealed by comparing the forming load, die wear and die stress predictions of non-isothermal and isothermal FEAs. The experiments have shown that the predictions of isothermal FEA are not feasible because of the high predicted effective stress on the weakest part of the die.

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“…It is well known that the occurrence of macroscopic shear bands (MSBs) is highly related to the strain inhomogeneity of flat-rolled wire [8], because the occurrence of MSBs indicates that the deformation is highly inhomogeneous during the 2 of 10 forming process. The occurrence of MSBs has been reported in several compression-type metal-forming processes, such as plain strain compression [15], uniaxial compression [16], flat rolling of wire [8], and flat roll drawing [17]. The restricted metal flow at the interface between the specimen and tool is the main reason for the occurrence of MSBs in specimens during the compression-type forming process.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cambered and Oval-Grooved Roll on the Strain Distribution During the Flat Rolling Process of a Wire

Hwang

2020

Processes

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The effect of the roll design on the strain distribution of the flat surface, lateral spreading, and the strain inhomogeneity of a flat-rolled wire were investigated during the flat rolling process. Oval-grooved and cambered rolls with various radii were applied to the flat rolling process based on a numerical simulation. The effective strain on the flat surface of the wire increased when using a cambered roll due to the highly intensified contact pressure on the flat surface, while the effective strain on the flat surface of the wire decreased when using an oval-grooved roll. Lateral spreading decreased when using an oval-grooved roll because the spread in the free surface area of the wire was highly restricted by the oval-grooved roll shape. In contrast, the spread in the surface area increased when using a cambered roll due to the less-restricted metal flow at the free surface. Accordingly, a cambered roll with a small radius is highly recommended in order to improve the surface quality of flat-rolled wires. This is beneficial for industrial plants because the cambered roll can be easily applied in flat rolling plants.

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Effect of strain hardening capability on plastic deformation behaviors of material during metal forming

Cited by 44 publications

References 20 publications

A New Methodology for Predicting Brittle Fracture of Plastically Deformable Materials: Application to a Cold Shell Nosing Process

A New Methodology for Predicting Brittle Fracture of Plastically Deformable Materials: Application to a Cold Shell Nosing Process

Automatic Multi-Stage Cold Forging of an SUS304 Ball-Stud with a Hexagonal Hole at One End

Effect of Cambered and Oval-Grooved Roll on the Strain Distribution During the Flat Rolling Process of a Wire

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