Hot forged product

Patent metadata

Field	Value
Publication number	US-2019127817-A1
Application number	US-201616091828-A
Country	US
Kind code	A1
Filing date	May 20, 2016
Priority date	May 20, 2016
Publication date	May 2, 2019
Grant date	—

Abstract

There is provided a hot forged product having excellent wear resistance and fatigue strength even when the hot forged product is produced with a thermal refining treatment and a case hardening thermal treatment after hot forging omitted, and having a chemical composition consisting of, in mass %, C: 0.45 to 0.70%, Si: 0.01 to 0.70%, Mn: 1.0 to 1.7%, S: 0.01 to 0.1%, Cr: 0.05 to 0.25%, Al: 0.003 to 0.050%, N: 0.003 to 0.02% with the balance being Fe and impurities. The matrix at the depth of 500 μm to 5 mm from an unmachined surface of the forged product is a ferrite-pearlite structure, in which a pro-eutectoid ferrite area fraction is 3% or less or a pearlite structure, and the average diameter of pearlite colonies in the pearlite structure at the depth of 500 μm to 5 mm from the unmachined surface is 5.0 μm or less.

First claim

1 . A hot forged product having a chemical composition consisting of, in mass %,
C: 0.45 to 0.70%, Si: 0.01 to 0.70%, Mn: 1.0 to 1.7%, S: 0.01 to 0.1%, Cr: 0.05 to 0.25%, Al: 0.003 to 0.050%, N: 0.003 to 0.02%, Ca: 0 to 0.01%, Cu: 0 to 0.15%, and Ni: 0 to 0.15% with the balance being Fe and impurities, wherein a matrix at a depth of 500 μm to 5 mm from an unmachined surface of the forged product is a ferrite-pearlite structure, in which a pro-eutectoid ferrite area fraction is 3% or less or a pearlite structure, and an average diameter of pearlite colonies in the pearlite structure at the depth of 500 μm to 5 mm from the unmachined surface is 5.0 μm or less.

2 . The hot forged product according to claim 1 ,
wherein the Chemical composition contains Ca: 0.0005 to 0.01%.

3 . The hot forged product according to claim 1 ,
wherein the chemical composition contains at least one type selected from a group consisting of Cu: 0.02 to 0.15%, and Ni: 0.02 to 0.15%.

4 . The hot forged product according to claim 1 ,
wherein the hot forged product is a crankshaft.

5 . The hot forged product according to claim 2 ,
wherein the chemical composition contains at least one type selected from a group consisting of Cu: 0.02 to 0.15%, and Ni: 0.02 to 0.15%.

6 . The hot forged product according to claim 2 ,
wherein the hot forged product is a crankshaft.

7 . The hot forged product according to claim 3 ,
wherein the hot forged product is a crankshaft.

8 . The hot forged product according to claim 5 ,
wherein the hot forged product is a crankshaft.

Assignees

• Nippon Steel & Sumitomo Metal Corp

Inventors

• Nishihara Kison
• Kashiwara Yoshiyuki
• Tahira Hiroaki

Classifications

• C21D8/00

  Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) · CPC title

• C22C38/12

  containing tungsten, tantalum, molybdenum, vanadium, or niobium · CPC title

• C22C38/42

  with copper · CPC title

• C21D6/004

  containing Cr and Ni · CPC title

• C22C38/02

  containing silicon · CPC title