Invention Grant
- Patent Title: Seamless precision steel tubes with improved isotropic toughness at low temperature for hydraulic cylinders and process for obtaining the same
- Patent Title (中): 用于液压缸的低温各向同性韧性提高的无缝精密钢管及其制造方法
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Application No.: US12306917Application Date: 2006-06-29
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Publication No.: US08926771B2Publication Date: 2015-01-06
- Inventor: Gianmario Agazzi , Emanuele Paravicini Bagliani , Andrea Poli
- Applicant: Gianmario Agazzi , Emanuele Paravicini Bagliani , Andrea Poli
- Applicant Address: VC Kingstown
- Assignee: Tenaris Connections Limited
- Current Assignee: Tenaris Connections Limited
- Current Assignee Address: VC Kingstown
- Agency: Knobbe Martens Olson & Bear LLP
- International Application: PCT/EP2006/063701 WO 20060629
- International Announcement: WO2008/000300 WO 20080103
- Main IPC: C21D9/08
- IPC: C21D9/08 ; C21D8/10 ; C21D1/18 ; C22C38/02 ; C22C38/04

Abstract:
Process for manufacturing seamless precision steel tubes with improved isotropic toughness at low temperature for hydraulic cylinders comprising the following steps; —(i) providing a steel having a composition comprising 0.06-0.15% by weight of carbon, 0.30-2.5% by weight of Mn, and 0.10-0.60% by weight of Si, —(ii) hot-rolling the said steel at a temperature higher than Ac3 such as to obtain a seamless steel tube, —(iii) heating the said seamless steel tube at a temperature in the range between Ac1 and Ac3, —(iv) quenching the said heated seamless steel tube, such as to establish a dual (or multi-) phase microstructure in the steel employed, composed of ferrite and martensite and optionally bainite and/or retained austenite, —(v) cold drawing the quenched seamless steel tube such as to provide a seamless precision steel tube of the desired dimensions, —(vi) subjecting the so-obtained seamless precision steel tube to stress relieving treatment to improve its isotropic toughness, and optionally —(vii) straightening the so-obtained seamless precision steel tube with improved toughness.
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