Forming Limit Diagrams of Perforated St12 Steel Sheets

Abstract One of the unique characteristics of sheet metals is their formability, which is determined by the forming limit diagrams. These diagrams specify the maximum deformation limit before part’s failure. For several applications of metal sheets, they have to be in the perforated format. Existence of holes in the perforated sheets may adversely deteriorate the forming limit of metal sheets. In this study, the effect of perforated sheets’ hole size and hole layout on their formability are investigated. Several specimens of St12 steel with 0.6 mm thickness, different widths, two various hole sizes of 2 and 4 mm, and two layouts of triangular and square were prepared. The specimens were tested using Nakajima test (stretch with a hemispherical punch) to generate the forming limit diagrams. It was observed that both the diameter and layout of the punched holes have a significant effect on the formability of the perforated sheets. The perforated sheets with triangular hole layout showed higher forming limits due to their larger ligament ratios.

Download Full-text

Forming Limit Diagrams of Perforated St12 Steel Sheets

10.21203/rs.3.rs-1025499/v1 ◽

2021 ◽

Author(s):

M. Hossein Sehhat ◽

Ali Mahdianikhotbesara ◽

Mohammadjafar Hadad

Keyword(s):

Forming Limit ◽

Sheet Metals ◽

Forming Limit Diagrams ◽

Maximum Deformation ◽

Steel Sheets ◽

Deformation Limit ◽

Metal Sheets ◽

Perforated Sheets ◽

Nakajima Test ◽

Hemispherical Punch

Download Full-text

Strain-rate-dependent forming limit diagrams for sheet metals

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1243/09544054jem1193 ◽

2008 ◽

Vol 222 (12) ◽

pp. 1651-1659 ◽

Cited By ~ 18

Author(s):

M Gerdooei ◽

B M Dariani

Keyword(s):

Strain Rate ◽

Forming Limit ◽

Sheet Metals ◽

Forming Limit Diagrams ◽

Rate Dependent

Download Full-text

Influence of Pre-Forming on the Forming Limit Diagram of Aluminum and Steel Sheets

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.344.113 ◽

2007 ◽

Vol 344 ◽

pp. 113-118 ◽

Cited By ~ 4

Author(s):

Massimo Tolazzi ◽

Marion Merklein

Keyword(s):

Dual Phase Steel ◽

Process Analysis ◽

Forming Limit Diagram ◽

Forming Limit ◽

Linear Strain ◽

Forming Limit Diagrams ◽

Steel Sheets ◽

Biaxial Stretching ◽

Strain Paths

This paper presents a method for the experimental determination of forming limit diagrams under non linear strain paths. The method consists in pre-forming the sheets under two different strain conditions: uniaxial and biaxial, and then stretching the samples, cut out of the preformed sheets, using a Nakajima testing setup. The optical deformation measurement system used for the process analysis (ARAMIS, Company GOM) allows to record and to analyze the strain distribution very precisely with respect to both time and space. As a reference also the FLDs of the investigated grades (the deep drawing steel DC04, the dual phase steel DP450 and the aluminum alloy AA5754) in as-received conditions were determined. The results show as expected an influence of the pre-forming conditions on the forming limit of the materials, with an increased formability in the case of biaxial stretching after uniaxial pre-forming and a reduced formability for uniaxial load after biaxial stretching if compared to the case of linear strain paths. These effects can be observed for all the investigated materials and can be also described in terms of a shifting of the FLD, which is related to the art and magnitude of the pre-deformation.

Download Full-text