发明名称 |
PROCESS FOR MANUFACTURING SEAMLESS STEEL PIPE |
摘要 |
There are provided: a seamless steel pipe formed from a cylindrical steel material billet through a hot isostatic extrusion step, wherein a depth of a contiguous flaw formed on an inner periphery surface and an outer periphery surface of the steel pipe is 50 µm or less; a hollow spring obtained by forming a hollow body in a shape of a coil or a bar or a bar with curved part from the seamless steel pipe made of spring steel and applying a surface treatment to the hollow body so that the hollow body has compressive residual stress; and a method for producing seamless steel pipe including: a billet molding step; a first heating step; a hot isostatic extrusion step; a second heating step; an extension step; a third heating step; and a pickling step. |
申请公布号 |
KR20130087626(A) |
申请公布日期 |
2013.08.06 |
申请号 |
KR20137018983 |
申请日期 |
2007.03.14 |
申请人 |
NHK SPRING CO., LTD.;SHINKO METAL PRODUCTS CO., LTD. |
发明人 |
TOYOTAKE KOTARO;IWAYA KOJI;MINAMI TOMOYUKI;TAKAMURA NORITOSHI |
分类号 |
B21C23/08;B21B21/00;B21C1/22;F16L9/02 |
主分类号 |
B21C23/08 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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