Improving deep drawability of HC300LA sheet metal by warm forming


Sen N., Kurgan N.

INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY, cilt.82, ss.985-995, 2016 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 82
  • Basım Tarihi: 2016
  • Doi Numarası: 10.1007/s00170-015-7400-z
  • Dergi Adı: INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
  • Sayfa Sayıları: ss.985-995

Özet

The formability of high-strength sheet materials is limited at room temperatures. In this study, the first of its kind to be conducted, experimental research was performed on the formability of HC300LA-grade sheet material using the warm deep drawing (WDD) method. Temperature control is among the most important parameters in the WDD method. To increase the limiting drawing ratio (LDR) of HC300LA-grade sheet material, a new warm deep drawing method featuring sensitive temperature control was designed and manufactured. With this new method, the formability of HC300L-grade sheet material was considerably increased by heating the flange zone of the blanks under blank-holder force (BHF). Before the experimental study, unidirectional tensile tests were applied at room temperature (RT), 150 degrees C, and 300 degrees C. At the completion of the test conducted at 300 degrees C, dynamic strain aging (DSA) was seen in the test specimen. As a result of DSA, the HC300LA-grade sheet material became brittle and its formability decreased. Experimental studies were therefore conducted in the temperature range of 170 and 295 degrees C. LDR for a 1.2-mm sheet thickness of HC300LA-grade sheet material, which is 2.14 at RT, increased to 2.61 after applying this method. In experimental studies on LDR involving 1.5-mm sheet thickness, which is 2.15 at RT, the ratio increased to 2.59. The drawing ratio (DR) increased by 21.96 and 20.45 % for 1.2 mm sheet thickness and 1.5 mm sheet thickness, respectively. Moreover, 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.