公开(公告)号：US20240209469A1

公开(公告)日：2024-06-27

申请号：US18563290

申请日：2022-05-25

申请人： BAOSHAN IRON & STEEL CO., LTD.

发明人： Zan Yao ,  Ziquan Yu ,  Feng Jin ,  Sixin Zhao ,  Haoyang Zhao

IPC分类号： C21D9/00 ,  C21C7/10 ,  C21D1/18 ,  C21D1/32 ,  C21D1/84 ,  C21D6/00 ,  C21D8/00 ,  C22C33/04 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46

CPC分类号： C21D9/0093 ,  C21C7/10 ,  C21D1/18 ,  C21D1/32 ,  C21D1/84 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/005 ,  C22C33/04 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C21D2211/00

摘要： The present invention discloses a steel for bolts, which comprises the following chemical elements in percentage by mass in addition to Fe and inevitable impurities: C: 0.37 to 0.45%; Si: 0.01 to 0.08%; Mn: 0.45 to 0.80%; Cr: 0.90 to 1.30%; Mo: 0.20 to 0.45%; Ni: 0.10 to 0.30%; V: 0.15 to 0.30%; and Al: 0.015 to 0.035%. The present invention further discloses a method for manufacturing the steel for bolts, which comprises the following steps: (1) smelting; (2) casting; (3) rough rolling; (4) high-speed wire rolling; (5) Stelmor controlled cooling; and (6) heat treatment, wherein the holding temperature of spheroidizing heat treatment is 760 to 790° C. and the holding time is 4 to 12 h, followed by a slow cooling process after the holding with a cooling speed of lower than 40° C./h. The drawing area reduction rate of a coil rod is controlled to 5 to 30%. The heating temperature of quenching and tempering heat treatment is 850 to 950° C. The tempering temperature is 500 to 600° C. The steel for bolts disclosed in the present invention has a uniform structure and performance, has low production costs, and has high strength and good delayed fracture resistance.