公开(公告)号：US20200080180A1

公开(公告)日：2020-03-12

申请号：US16467225

申请日：2018-08-08

Applicant: OSAKA UNIVERSITY ,  KOMATSU LTD.

Inventor： Yoritoshi MINAMINO ,  Koji HAGIHARA ,  Koji YAMAMOTO ,  Shohei IKURUMI ,  Yusuke HIRATSUKA ,  Takeshi FUJIMATSU ,  Toshiyuki SUGIMOTO

IPC: C22C38/46 ,  C22C38/44 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D6/00 ,  C21D6/02 ,  C21D1/28

Abstract: A steel with high hardness and excellent toughness contains, in mass %, 0.40-1.00% C, 0.10-2.00% Si, 0.10-1.00% Mn, 0.030% or less P, 0.030% or less S, 1.10-3.20% Cr, 0.010-0.10% Al, and 0.15-0.50% V, and further contains at least one or two of 2.50% or less Ni and 1.00% or less Mo, with an amount of (C+V) being 0.60% or more in mass %, with the balance consisting of Fe and unavoidable impurities. The steel has a microstructure which is a martensitic structure with finely dispersed Fe-based ε carbides, with its prior austenite grain size being 20 μm or less.

公开(公告)号：US20200165710A1

公开(公告)日：2020-05-28

申请号：US15757968

申请日：2016-09-16

Applicant: OSAKA UNIVERSITY ,  KOMATSU LTD.

Inventor： Yoritoshi MINAMINO ,  Takemori TAKAYAMA ,  Koji YAMAMOTO ,  Yusuke HIRATSUKA

IPC: C22C38/58 ,  C22C38/34 ,  C22C38/06 ,  C22C38/44 ,  C22C38/46

Abstract: A steel with high hardness and excellent toughness contains, in mass %, 0.55-1.10% C, 0.10-2.00% Si, 0.10-2.00% Mn, 0.030% or less P, 0.030% or less S, 1.10-2.50% Cr, and 0.010-0.10% Al, with the balance consisting of Fe and unavoidable impurities. The structure of the steel after quenching is a dual phase structure of martensitic structure and spheroidized carbide. Spheroidized cementite particles with an aspect ratio of 1.5 or less constitute at least 90% of all cementite particles. The proportion of the number of spheroidized cementite particles on the prior austenite grain boundaries to a total number of cementite particles is 20% or less.