Crankshaft

Patent metadata

Field	Value
Publication number	US-12352309-B2
Application number	US-202118005877-A
Country	US
Kind code	B2
Filing date	Sep 24, 2021
Priority date	Sep 28, 2020
Publication date	Jul 8, 2025
Grant date	Jul 8, 2025

Abstract

A crankshaft with improved seizure resistance is provided. A crankshaft ( 10 ) is a crankshaft including journals ( 11 ) and pins ( 12 ), having a chemical composition of, in mass %: 0.35 to 0.40% C; up to 0.70% Si; 1.00 to 2.00% Mn; up to 0.50% Cr; up to 0.050% Al; up to 0.020% N; up to 0.020% P; 0.005 to 0.200% S; and balance Fe and impurities, each of the journals ( 11 ) and pins ( 12 ) having a surface microstructure containing tempered martensite in not less than 80 volume % and a surface hardness not higher than HV 450.

First claim

The invention claimed is:

1. A crankshaft comprising a journal and a pin, the crankshaft having a chemical composition of, in mass %:
0.35 to 0.40% C;
up to 0.70% Si;
1.00 to 2.00% Mn;
up to 0.50% Cr;
up to 0.050% Al;
up to 0.020% N;
up to 0.020% P;
0.005 to 0.200% S; and
balance Fe and impurities,
for each of the journal and the pin, a microstructure of a surface containing tempered martensite in not less than 80 volume % and a hardness of the surface being not higher than HV 450.

2. The crankshaft according to claim 1 , further comprising a fillet,
wherein a hardness of the fillet from a surface down to a depth of 2.0 mm is not lower than HV 580.

3. The crankshaft according to claim 2 , wherein a microstructure of the fillet from the surface down to the depth of 2.0 mm contains martensite in not less than 80 volume %.

4. The crankshaft according to claim 1 , wherein the hardness of the surface of each of the journal and the pin is not higher than HV 250.

5. The crankshaft according to claim 1 , wherein the microstructure of the surface of each of the journal and the pin further contains cementite in not less than 10 volume %.

6. The crankshaft according to claim 1 , wherein a surface roughness Ra of each of the journal and the pin is not higher than 0.100 μm.

Assignees

• Nippon Steel Corp
• Toyota Motor Co Ltd

Inventors

• Abe Tatsuhiko
• Kubota Manabu
• Okawa Satoru
• Murakami Motoichi
• Koyama Takashi
• Morita Yusuke
• Fukui Takeshi
• Inukai Yusuke
• Kajiki Yuichiro

Classifications

• C22C38/04

  containing manganese · CPC title

• C22C38/00

  Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00) · CPC title

• C21D9/30

  for crankshafts; for camshafts · CPC title

• C22C38/60 Primary

  containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur · CPC title

• C22C38/38

  with more than 1.5% by weight of manganese · CPC title