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Vol.32, No.6, 649 ~ 658, 1994
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| Title |
| Cracking Phenomena during Deep Drawing of Hot Rolled Steel Strips ( Part Ⅰ. The Effect of grain Boundary Carbides on the Crack Formation )
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| 이성학Sung Hak Lee, 이창길Chang Gil Lee, 박우진Woo Jin Park, 김낙준Nack J . Kim, 권동일Dong il Kwon, 장영원Young Won Chang |
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| Abstract |
| An investigation was conducted to examine the effects of microstructural parameters on the cracking behavior, often occurred in the top parts of the deep drawn cups of hot rolled formable steel. Particular emphasis was placed on the role of grain boundary carbides in the carcking phenomenon. Detailed microstructural analyses of the cracked region showed that a number of voids initiated at grain boundary carbides were observed to form intergranular cracks. These grain boundary carbides were identified as Mn-containing Fe₃C carbides which might be associated with the formation of the band structure. In the microstucture of the hot rolled steel, film or bulk-type carbides along grain boundaries, together with banded ferrite-pearlite structures, were commonly observed, and were thought to initiate cracks during deep drawing process. Thus the formation of grain boundary carbides and band structures must be minimized to prevent cracking. A1 killing process, homogenization treatment and low temperature coiling treatment are suggested as possible methods for minimizing the amount of grain boundary carbides. |
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