scholarly journals Improving Trimmed Surface of High Tensile Strength Steel Sheets

2014 ◽  
Vol 55 (642) ◽  
pp. 633-637
Author(s):  
Nobuhiro KOGA ◽  
Ying CHEN
Author(s):  
Takashi MATSUOKA ◽  
Toshihiko KAWAI ◽  
Yoshihiko HOBO ◽  
Shin-ya UEDA

2014 ◽  
Vol 622-623 ◽  
pp. 1075-1080 ◽  
Author(s):  
Kota Sakumoto ◽  
Kazuhiko Yamazaki ◽  
Takashi Kobayashi ◽  
Shinsuke Suzuki

We investigated punching properties (crack in punched surface and hole expansion ratio) of high tensile strength steel sheets with and without center segregation. High strength steel sheets were heat-treated to reduce center segregation. Tensile strength, shear surface ratio, depth of rollover and burr height were measured on heat-treated steel sheets to confirm the effect of heat-treatment on strength. The EPMA analysis showed that the center segregation of Mn was reduced by the diffusion during heat-treatment. Crack-formation frequency and hole expansion ratio were also measured. As a result, the center segregation of Mn in high tensile strength steel sheets decreased by the heat-treatment (600 oC for 100 h) with maintaining the tensile strength, the depth of rollover and the burr height. The crack-formation frequency of the steel sheets decreased through heat-treatments.


2013 ◽  
Vol 554-557 ◽  
pp. 1320-1330 ◽  
Author(s):  
Taro Geka ◽  
Masayuki Asakura ◽  
Takuma Kiso ◽  
Takashi Sugiyama ◽  
Masato Takamura ◽  
...  

This study investigated the twisting phenomenon in curved hat channel products made of dual-phase 980-MPa-class high-tensile-strength steel sheets. The stroke returning deep drawing (SRDD) method was proposed to deal with twisting. In this new method, after the punch reaches the bottom dead point, it returns to a certain drawing height without the blank holder being removed. With the application of the SRDD method, twisting hardly occurred, but sidewall curl increased. A two-step SRDD was then proposed to reduce the sidewall curl of SRDD products. In the two-step SRDD method, a stroke returning process is carried out in two steps under different conditions. The results showed that the two-step SRDD method reduced the sidewall curl and twist simultaneously.


2012 ◽  
Vol 53 (617) ◽  
pp. 569-573 ◽  
Author(s):  
Yuzo TAKAHASHI ◽  
Satoshi HORIOKA ◽  
Osamu KAWANO ◽  
Masahiro OHARA ◽  
Kohsaku USHIODA

2017 ◽  
Vol 207 ◽  
pp. 1594-1598 ◽  
Author(s):  
Takeshi Uemori ◽  
Tetsuo Naka ◽  
Naoya Tada ◽  
Hidenori Yoshimura ◽  
Takashi Katahira ◽  
...  

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