Denso Corporation

Nippon Steel Sumitomo Metal Corporation

Daido Steel Co., Ltd.

Nippon Steel Corporation

Toshimasa Ito

Tadashi Nishiwaki

Tomomitsu Fukuoka

Takahiro Miyazaki

Yoshihiro Tanimura

Kouji Morita

Yuuki Tanaka

Makoto Haritani

Hitoshi Matsumoto

Yutaka Neishi

Koji Morita

Tatsuya Hasegawa

Kazuyoshi Kimura

Taizo Makino

Masato Yuya

Masashi Higashida

Motoki Takasuga

Keisuke Inoue

Tomohiro Andoh

Yoshiro Tanimura

A workpiece for a fuel injection component is made of a steel having compositions, by mass %, of C: 0.08 to 0.16%, Si: 0.10 to 0.30%, Mn: 1.00 to 2.00%, S: 0.005 to 0.030%, Cu: 0.01 to 0.30%, Ni: 0.40 to 1.50%, Cr: 0.50 to 1.50%, Mo: 0.30 to 0.70%, V: 0.10 to 0.40%, s-Al: 0.001 to 0.100%, and Fe and unavoidable impurities as remaining components. After heating the workpiece to a temperature of 950&#xb0; C. or more and 1350&#xb0; C. or less, the workpiece is subjected to a hot forging, and thereafter cooled at an average cooling rate of 0.1&#xb0; C./sec. or more in a temperature range from 800&#xb0; C. to 500&#xb0; C., and at the average cooling rate of 0.02&#xb0; C./sec. or more and 10&#xb0; C./sec. or less in the subsequent temperature range from 500&#xb0; C. to 300&#xb0; C. to set an area ratio of a bainite structure after hot forging to 85% or more.

Method for manufacturing fuel injection component

The present invention provides an age hardening type bainitic microalloyed steel having a composition which includes, in terms of mass %: 0.06-0.35% of C; 0.01-2.00% of Si; 0.10-3.00% of Mn; 0.001-0.200% of S; 0.001-2.00% of Cu; 0.40-3.00% of Ni; 0.10-3.00% of Cr; 0.10-1.00% of Mo; 0.10-1.00% of V; and 0.001-0.100% of s-Al, with the remainder being Fe and unavoidable impurities, and which satisfies a value of the following expression (1) to be 20 or larger and a value of the following expression (2) to be 0.82 or larger:3&#xd7;[C]+10&#xd7;[Mn]+2&#xd7;[Cu]+2&#xd7;[Ni]+12&#xd7;[Cr]+9&#xd7;[Mo]+2&#xd7;[V]&#x2003;&#x2003;expression (1);1.66&#xd7;[C]+0.18&#xd7;[Si]+0.27&#xd7;[Mn]+0.09&#xd7;[Ni]+0.32&#xd7;[Cr]+0.34&#xd7;[Mo]+0.44&#xd7;[V]&#x2003;&#x2003;expression (2),in which each [ ] in the expression (1) and the expression (2) indicates a content of the element shown therein in terms of mass %.

Age hardening non-heat treated bainitic steel

An age-hardenable steel having a composition consisting of: C: 0.05 to 0.20%, Si: 0.01 to 0.50%, Mn: 1.5 to 2.5%, S: 0.005 to 0.08%, Cr: more than 0.50% and not more than 1.6%, Al: 0.005 to 0.05%, V: 0.25 to 0.50%, Mo: 0 to 1.0%, Cu: 0 to 0.3%, Ni: 0 to 0.3%, Ca: 0 to 0.005%, and Bi: 0 to 0.4%, the balance being Fe and impurities. Within the impurities, P&#x2264;0.03%, Ti&#x3c;0.005%, and N&#x3c;0.0080%, and [C+0.3Mn+0.25Cr+0.6Mo&#x2265;0.68], [C+0.1Si+0.2Mn+0.15Cr+0.35V+0.2Mo&#x2264;1.05], and [&#x2212;4.5C+Mn+Cr&#x2212;3.5V&#x2212;0.8Mo&#x2265;0.12]. The steel has hardness before aging of not more than 310 HV. After aging, the fatigue strength is not less than 480 MPa and absorbed energy at 20&#xb0; C. is not less than 12 J.

Age-hardenable steel

Growing community of inventors

Aichi, Japan

Toshimasa Ito