公开(公告)号：US11332817B2

公开(公告)日：2022-05-17

申请号：US17046064

申请日：2019-05-10

申请人： KOMATSU LTD.

发明人： Kensuke Sato ,  Koji Yamamoto ,  Yusuke Hiratsuka ,  Kazuya Hashimoto

IPC分类号： C22C38/00 ,  C23C8/22 ,  C21D1/32 ,  C21D9/32 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C23C8/80

摘要： A machine component includes a core made up of a steel for machine structural use, and a medium carbon-containing layer and a high carbon-containing layer formed of the steel for machine structural use, the medium carbon-containing layer covering the core, the high carbon-containing layer covering the medium carbon-containing layer and having a carbon concentration of 0.8-1.5%. The high carbon-containing layer is made up of a martensitic structure having carbides dispersed therein and a residual austenitic structure, wherein spheroidized carbides with an aspect ratio of 1.5 or less constitute 90% or more of a total number of the carbides, and the number of spheroidized carbides on prior austenite grain boundaries is 40% or less of the total number of the carbides.

公开(公告)号：US11326220B2

公开(公告)日：2022-05-10

申请号：US17046087

申请日：2019-05-10

申请人： KOMATSU LTD.

发明人： Kensuke Sato ,  Koji Yamamoto ,  Yusuke Hiratsuka ,  Kazuya Hashimoto

IPC分类号： C21D9/32 ,  C21D1/06 ,  C21D1/32 ,  C21D6/00 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/44 ,  C23C8/22 ,  C23C8/80

摘要： A method for producing a machine component excellent in pitting resistance characteristics and toughness includes a carburizing step, performed on a steel material containing 0.13-0.30% C and 0.90-2.00% Cr in mass % and at least one of Si, Mn, Ni, Mo, Nb, V, Ti, B, Al, and N, balance Fe and unavoidable impurities; heating the material to 850-1030° C. to attain carbon concentration in a surface of 0.8-1.5%; cooling the material at an average rate of 5° C./sec or lower from a temperature higher than the Acm point of a surface layer to a cooling end temperature that is at least 50° C. lower than the A1 point to cause the surface layer to have a pearlite or bainite structure with dispersion; spheroidizing annealing at a temperature not higher than the Acm point at the surface layer; heating the material to not higher than the Acm point at the surface layer; and performing tempering.