公开(公告)号：US20180265940A1

公开(公告)日：2018-09-20

申请号：US15537578

申请日：2016-03-10

申请人： NIPPON STEEL & SUMITOMO METAL CORPORATION

发明人： Manabu KUBOTA ,  Koichi BANNO ,  Keisuke CHIBA ,  Ryuuichi SEKI

IPC分类号： C21D8/06 ,  C21D9/52 ,  C22C38/02 ,  C22C38/06 ,  C22C38/58 ,  C22C38/42 ,  C22C38/44 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  F16F1/02 ,  C22C38/46

摘要： Steel for a suspension spring including, as a chemical composition, by % by mass: C: more than 0.40% and 0.65% or less; Si: 1.00% to 3.50%; Mn: more than 2.00% and 3.00% or less; Cr: 0.01% to 2.00%; V: 0.02% to 0.50%; P: 0.020% or less; S: 0.020% or less: N: 0.0100% or less; and a remainder of Fe and impurities, in which Kf is 280 or more, in which a structure contains a tempered martensite of which an area ratio is 90% or more, in which a Fe-based carbide precipitated in the tempered martensite is a cementite, and in which an average of an area ratios of prior austenite grains which stretch in a longitudinal direction of the steel and of which an aspect ratio exceeds 3.0, is 80% or more in a case of depths of 0.1 mm, 0.2 mm, and 0.3 mm in a sheet thickness direction from a surface of the steel.

公开(公告)号：US20160273067A1

公开(公告)日：2016-09-22

申请号：US15032496

申请日：2014-11-18

申请人： NIPPON STEEL & SUMITOMO METAL CORPORATION

发明人： Atsushi MONDEN ,  Shunta HOMMA ,  Koichi BANNO

IPC分类号： C21D9/52 ,  C22C38/22 ,  C22C38/18 ,  C22C38/16 ,  C22C38/14 ,  C21D1/06 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D3/04 ,  C22C38/60 ,  C22C38/12

CPC分类号： C21D9/525 ,  C21D1/06 ,  C21D3/04 ,  C21D8/06 ,  C21D8/065 ,  C21D9/52 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/22 ,  C22C38/60

摘要： A steel bar according to one embodiment of the present invention includes predetermined chemical composition, wherein a quenching deflection in a cross section is 1.5 mm or less, wherein Δmax and Δmin is 1.5 mm or less, wherein a structure in a surface layer area includes 10 area % or less of ferrite and a remainder including one or more selected from a group consisting of a bainite and a martensite, wherein an average value of the grain size of a bcc phase in the surface layer area is 1.0 to 10.0 μm, wherein an average value of the grain size of the bcc phase in a center area is 1.0 to 15.0 μm, wherein a hardness of a region of which a depth from the surface is 50 μm is Hv200 to Hv500, and wherein a total decarburized layer thickness DM-T is 0.20 mm or less.

摘要翻译： 根据本发明的一个实施方案的钢筋包括预定的化学组成，其中截面中的淬火偏转为1.5mm或更小，其中Δmax和Δmin为1.5mm或更小，其中表面层区域中的结构包括10 面积％以下的铁素体，剩余部分包括选自由贝氏体和马氏体组成的组中的一种或多种，​​其中表层区域中bcc相的晶粒尺寸的平均值为1.0〜10.0μm，其中， 中心区域的bcc相的晶粒尺寸的平均值为1.0〜15.0μm，其中表面深度为50μm的区域的硬度为Hv200〜Hv500，其中，总脱碳层厚度DM- T为0.20mm以下。