Formability of austenitic and ferritic stainless steels at warm forming temperature

Bong, Hyuk Jong; Barlat, Frédéric; Ahn, Doyeol; Kim, Heon‐Young; Lee, Myoung‐Gyu

doi:10.1016/j.ijmecsci.2013.05.017

Cited by 52 publications

(18 citation statements)

References 34 publications

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“…A new method, unlike any used in previous studies on warm forming, was developed in this study for conducting both heating and cooling processes. Bong et al [2], Wang at al. [8], and Laurent et al [9] used cartridge-type heaters as the heating system in studies.…”

Section: Introductionmentioning

confidence: 97%

“…Bong et al [2] defined that cup drawing is among the most widely applied tests used to assess the formability of a wide range of sheet metals. This test involves various deformation modes, such as plane strain tension (in cup wall), bending (at punch and die corners), biaxial stretching (at cup bottom), and pure shear (in flange).…”

Section: Introductionmentioning

confidence: 99%

“…Stainless steels feature high corrosion resistance, high mechanical strength, and good surface appearance. Bong et al [2] investigated the warm temperature drawability of an austenitic (STS 304) and ferritic stainless (STS 430) steel sheet by using the cup drawing test. The results showed that the measured LDRs increased to about 44 and 25 % for STS 304 and STS 430 via the warm forming process, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…This heating system prevented not only energy consumption but also probable oxidation in the blank during WDD process by minimizing the time required to heat blank and die. Bong et al [2], Ghaffari Tari et al [4], and Takuda et al [10] performed the cooling of the punch zone only by cooling channels in the punch. In the designed process, in addition to the induction-type heating system embedded in die, a new cooling system was also developed for the first time.…”

Section: Introductionmentioning

confidence: 99%

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Experimental research on warm deep drawing of HC420LA grade sheet material

Şen

Karaağaç

Kurgan

2016

Int J Adv Manuf Technol

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The use of high-strength sheet material applications in the automotive industry has become widespread due to their high strength/weight ratios. The formability, however, of these high-strength sheet materials is limited at room temperatures (RTs). In this study, the first of its kind to be conducted, experimental research was performed on the formability of HC420LA grade sheet material using the warm deep drawing (WDD) method. Temperature control is the most important parameter in WDD. In this method, a new temperature control system was designed and manufactured to increase the formability of HC420LA grade sheet material. The limiting drawing ratio (LDR) for a 1.2-mm sheet thickness of HC420LA grade sheet material, which is 2.14 at RT, increased to 2.47 after applying this method. For a 1.5-mm sheet thickness of HC420LA, LDR, which is 2.15 at RT, increased to 2.59 after applying this method. Percent increases of the drawing ratios for 1.2 and 1.5 mm thicknesses were 15.42 and 20.45 %, respectively. A maximum reduction of 15 % in thickness was obtained in formed cups. Lastly, the microstructures of the warm cup's punch corner region and wall and bottom regions were investigated under an optical microscope. The results showed whether any changes occurred in the microstructures and mechanical properties.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Experimental research on warm deep drawing of HC420LA grade sheet material

Şen

Karaağaç

Kurgan

2016

Int J Adv Manuf Technol

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“…For example, although a tube bending step is required as a pre-forming process in hydroforming technology, the low formability of ferritic stainless steels may lead to premature failure during the bending process as the final target components become complicated. 6) Exhaust manifolds can be classified into two general types depending on the manufacturing process: the stamping type, which is formed by pressing; and the tubular type, which is made of pipes. The stamping-type exhaust manifold is obtained by welding together upper and lower parts of the shell type.…”

Section: Introductionmentioning

confidence: 99%

Bending Formability of Ferritic Stainless Steels for Application to Tubular Exhaust Manifolds

2015

Self Cite

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In this study, the bending formability of tubular pipes made of ferritic stainless steels during the rotary bending process was investigated. Three different types of ferritic stainless steel-STS 439, STS 429EM, and STS 441-were selected as the test materials. Finite element (FE) simulations were introduced to predict maximum bending angles, or equivalently the bending formability, for both as-received and annealed tubes. The results from experiments and FE simulations suggest the following main conclusions. First, the pipe materials used in the rotary bending process were subjected to prior work hardening during the tubing process, which resulted in reduced formability. However, proper heat treatment could enhance the bending formability. The optimum annealing conditions were determined from the microstructure analysis and mechanical assessments by uni-axial tensile tests for various heat-treated samples. An annealing temperature/holding time of 900°C/10-60 s resulted in enhanced formability without grain coarsening for the three tested ferritic stainless steels. Second, a FE model predicted maximum bending angles and thinning profiles at the extrados of pipes for both as-received and heat-treated tubes when the boundary conditions and friction coefficients were properly optimized.

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Corrosion and hardness properties of retrogression‐formed and warm‐formed AA7075 sheet

Ogunsanya

2023

Engineering Reports

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To achieve combined formability and strength in high‐strength precipitation‐hardened aluminum automotive sheets, different forming path used with fast and slow forming technology has been proposed. This study reports hardness and corrosion properties from two elevated‐temperature forming techniques, retrogression forming (RF) and warm forming (WF), employed on AA7075 alloy sheets. Parameters such as optimal pre‐aging, re‐aging, WF, and RF temperature and time were determined. In the retrogression‐formed (R‐F) sheets, initial retrogression treatment of peak‐aged (i.e., T6) temper resulted in significant loss of properties, but final re‐aging step recovered most. When traditional peak‐aging treatment was used to re‐age R‐F sheets, their T6 hardness and corrosion properties were restored to 95%–97% and 86%, respectively, while re‐aging R‐F sheets using industrial post‐forming paint‐bake treatment restored their T6 hardness and corrosion properties to 87%–92% and 78%–79%. In the warm‐formed (W‐F) sheets, increasing pre‐aging temperature and time resulted in increasing properties, and properties of the best W‐F samples matched the R‐F samples. In addition, shorter‐time forming did not significantly reduce properties of formed part, encouraging the use fast‐forming technology. Overall, these findings show that sheets subjected to RF and WF techniques can possess T6 properties in formed parts.

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Formability of austenitic and ferritic stainless steels at warm forming temperature

Cited by 52 publications

References 34 publications

Experimental research on warm deep drawing of HC420LA grade sheet material

Experimental research on warm deep drawing of HC420LA grade sheet material

Bending Formability of Ferritic Stainless Steels for Application to Tubular Exhaust Manifolds

Corrosion and hardness properties of retrogression‐formed and warm‐formed AA7075 sheet

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