Investigations on warm forming of AW-7020-T6 alloy sheet

Kumar, M. S. Mohan; Sotirov, N.; Chimani, Christian

doi:10.1016/j.jmatprotec.2014.03.024

Cited by 82 publications

(36 citation statements)

References 13 publications

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“…The tests were performed using an 805 A/D Bähr deformation dilatometer. Details of the tensile sample geometry and deformation dilatometer were given in [6]. Each tensile sample was heated to the test temperature in 6 s and soaked for 4 s before each tensile test as shown in Figure 2(a).…”

Section: Tension Testmentioning

confidence: 99%

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Investigations on the Hot Stamping of AW-7921-T4 Alloy Sheet

Kumar

Ross

2017

Advances in Materials Science and Engineering

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AW-7xxx alloys have been nowadays considered for greater light weighting potential in automotive industry due to its higher strength compared to AW-5xxx and AW-6xxx alloys. However, due to their lower formability the forming processes are still in development. This paper investigates one such forming process called hot stamping. The investigation started by carrying out hot tensile testing of an AW-7xxx alloy, that is, AW-7921 at temperatures between 350°C and 475°C, to measure the strength and formability. Formability was found to improve with increasing temperature and was sensitive to the strain rate. Dynamic recovery is considered as usual reason for the formability improvement. However, examining the precipitation states of the as-received condition and after hot stamping using differential scanning calorimetry (DSC), the dissolution of precipitates was also believed to contribute to this increase in formability. Following solution heat treatment there was no precipitation during cooling across the cooling rates investigated (5–10°C/s). Samples taken from parts hot stamped at 10 and 20 mm s−1 had similar yield strengths. A 3-step paint baking heat treatment yielded a higher postpaint baking strength than a single step treatment.

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Section: Tension Testmentioning

confidence: 99%

“…The limited cold formability of AW-7xxx sheet can be enhanced by either forming the material in the W-and Otempers or forming at warm temperatures [4][5][6][7][8]. Forming with W-and O-temper requires costly heat treatment steps to produce distortion-free parts.…”

Section: Introductionmentioning

confidence: 99%

Investigations on the Hot Stamping of AW-7921-T4 Alloy Sheet

Kumar

Ross

2017

Advances in Materials Science and Engineering

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“…However, those conditions might provide insufficient levels of formability. Some promising methods for increasing the formability are retrogression and re-aging treatments (RRA), warm forming, and so-called hot forming [1][2][3]. Among the three, hot forming (forming at elevated temperature and simultaneous quenching directly after solution annealing) seems to be the most promising method [2,4].…”

Section: Introductionmentioning

confidence: 99%

Dissolution and Precipitation Behavior for Hot Forming of 7021 and 7075 Aluminum Alloys

Milkereit

Österreich

Schuster

et al. 2018

Metals

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Due to their high strength, 7xxx aluminum sheets are increasingly used for structural automobile components. One of the major challenges is the formability of these alloys during the production process while retaining high strengths in service. One promising method is forming at elevated temperatures directly after solution annealing; this is known as hot forming. However, this thermomechanical process requires a detailed comprehension of the dissolution and precipitation behavior during heating, solution annealing, and subsequent combination of forming and cooling processes. Therefore, the kinetics of solid-solid phase transformations during continuous heating and continuous cooling of the aluminum alloys EN AW-7021 and EN AW-7075 were determined with differential scanning calorimetry and hardness testing. The suitable solution annealing conditions and the critical cooling rates were specified for both alloys and compared to the real hot forming processes.

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“…To form deep draw shapes and complex geometries, forming processes, such as superplastic forming, warm forming [39], hot forming [40,41,42], and hydro-forming processes [43,44,45,46,47], are needed to form automotive parts. Due to higher silicon content in the aluminum alloys, the abrasive nature of the material make dies wear out faster using aluminum sheets than with mild steel.…”

Section: Aluminummentioning

confidence: 99%