发明名称 |
Method for producing a high strength hot-rolled steel plate exhibiting excellent acid pickling property, chemical conversion processability, fatigue property, stretch flangeability, and resistance to surface deterioration during molding, and having isotropic strength and ductility |
摘要 |
This high strength hot-rolled steel sheet includes: in terms of percent by mass, C: 0.05 to 0.12%; Si: 0.8 to 1.2%; Mn: 1.6 to 2.2%; Al: 0.30 to 0.6%; P: 0.05% or less; S: 0.005% or less; and N: 0.01% or less, with the remainder being Fe and unavoidable impurities, wherein a microstructure includes specific ranges (in area %) of ferrite phases as well as martensite phases, and a maximum concentration of Al detected by a glow discharge emission spectroscopic analysis is in a range of 0.75 mass % or less in a region from a surface of the steel sheet to a thickness of 500 nm after being acid-pickled. |
申请公布号 |
US9523134(B2) |
申请公布日期 |
2016.12.20 |
申请号 |
US201414470143 |
申请日期 |
2014.08.27 |
申请人 |
NIPPON STEEL & SUMITOMO METAL CORPORATION |
发明人 |
Tanahashi Hiroyuki;Saitoh Shinya;Fukuda Masashi;Okada Hiroyuki;Hayashi Kunio;Tomokiyo Toshimasa;Fujita Nobuhiro |
分类号 |
C21D8/02;C21D9/46;C22C38/00;C22C38/02;C22C38/04;C22C38/06;C23C2/06;C22C38/12;C22C38/14;C22C38/08;C22C38/16;C22C38/38 |
主分类号 |
C21D8/02 |
代理机构 |
Birch, Stewart, Kolasch & Birch, LLP |
代理人 |
Birch, Stewart, Kolasch & Birch, LLP |
主权项 |
1. A method for producing a high strength hot-rolled steel sheet that is superior in an acid pickling property, a chemical conversion processability, a fatigue property, a hole expandability, and a resistance to surface deterioration during forming, and that has isotropic strength and isotropic ductility, the method comprising:
a process of heating a slab at a heating temperature in a range of T1 or less and subjecting the slab to rough rolling under conditions in which a rolling reduction ratio is in a range of 80% or more and a final temperature is in a range of T2 or less to produce a rough rolled material; a process of subjecting the rough rolled material to descaling and subsequent finish rolling under a condition in which a finish temperature is set to be in a range of 700 to 950° C. to produce a rolled sheet; a process of cooling the rolled sheet to a temperature in a range of 550 to 750° C. at an average cooling rate of 5 to 90° C./s, further cooling the rolled sheet to a temperature in a range of 450 to 700° C. at an average cooling rate of 15° C./s or less, and further cooling the rolled sheet to a temperature in a range of 250° C. or less at an average cooling rate of 30° C./s or more to produce a hot-rolled steel sheet; and a process of coiling the hot-rolled steel sheet, wherein
T1=1215+35×[Si]−70×[Al],T2=1070+35×[Si]−70×[Al], and [Si] and [Al] represent a Si content (mass %) in the slab, and an Al content (mass %) in the slab, respectively. |
地址 |
Tokyo JP |