Bearing steel having improved fatigue durability and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-2016145702-A1
Application number	US-201514939475-A
Country	US
Kind code	A1
Filing date	Nov 12, 2015
Priority date	Nov 24, 2014
Publication date	May 26, 2016
Grant date	—

Abstract

Disclose is an alloy composition for bearing steel having improved fatigue durability and a method of manufacturing the bearing steel comprising the same. The alloy composition comprises: based on a total weight of the alloy composition, an amount of about 0.8 to 1.0 wt % of carbon (C), an amount of about 0.35 to 0.9 wt % of silicon (Si), an amount of about 0.5 to 1.0 wt % of manganese (Mn), an amount of about 0.6 to 1.5 wt % of nickel (Ni), an amount of about 1.2 to 1.55 wt % of chromium (Cr), an amount of about 0.2 to 0.5 wt % of molybdenum (Mo), an amount of about 0.01 to 0.06 wt % of aluminum (Al), an amount of about 0.01 to 0.1 wt % of copper (Cu), and iron (Fe) constituting the balance of the weight of the alloy composition. Preferred alloy composition can provide improved strength, hardness, and fatigue life due to spheroidized carbide complex.

First claim

What is claimed is:

1 . An alloy composition for bearing steel, comprising:
an amount of about 0.8 to 1.0 wt % of carbon (C); an amount of about 0.35 to 0.9 wt % of silicon (Si); an amount of about 0.5 to 1.0 wt % of manganese (Mn); an amount of about 0.6 to 1.5 wt % of nickel (Ni); an amount of about 1.2 to 1.55 wt % of chromium (Cr); an amount of about 0.2 to 0.5 wt % of molybdenum (Mo); an amount of about 0.01 to 0.06 wt % of aluminum (Al); an amount of about 0.01 to 0.1 wt % of copper (Cu); and iron (Fe) constituting the balance of the weight of the alloy composition, all the wt % based on the total weight of the alloy composition.

2 . The alloy composition of claim 1 further comprising one or more selected from the group consisting of an amount of more than 0 wt % and about 0.38 wt % or less of vanadium (V) and an amount of more than 0 wt % and about 0.02 wt % or less of niobium (Nb), all the wt % based on the total weight of the alloy composition.

3 . The alloy composition of claim 1 , wherein the alloy composition further comprises an amount of about 0.006 wt % or less of nitrogen (N), an amount of about 0.001 wt % or less of oxygen (O), an amount of about 0.03 wt % or less of phosphorus (P), and an amount of about 0.01 wt % or less of sulfur (S), all the wt % based on the total weight of the alloy composition.

4 . The alloy composition of claim 1 , consisting essentially of:
an amount of about 0.8 to 1.0 wt % of carbon (C); an amount of about 0.35 to 0.9 wt % of silicon (Si); an amount of about 0.5 to 1.0 wt % of manganese (Mn); an amount of about 0.6 to 1.5 wt % of nickel (Ni); an amount of about 1.2 to 1.55 wt % of chromium (Cr); an amount of about 0.2 to 0.5 wt % of molybdenum (Mo); an amount of about 0.01 to 0.06 wt % of aluminum (Al); an amount of about 0.01 to 0.1 wt % of copper (Cu); and iron (Fe) constituting the balance of the weight of the alloy composition, all the wt % based on the total weight of the alloy composition.

5 . The alloy composition of claim 1 , consisting essentially of:
an amount of about 0.8 to 1.0 wt % of carbon (C); an amount of about 0.35 to 0.9 wt % of silicon (Si); an amount of about 0.5 to 1.0 wt % of manganese (Mn); an amount of about 0.6 to 1.5 wt % of nickel (Ni); an amount of about 1.2 to 1.55 wt % of chromium (Cr); an amount of about 0.2 to 0.5 wt % of molybdenum (Mo); an amount of about 0.01 to 0.06 wt % of aluminum (Al); an amount of about 0.01 to 0.1 wt % of copper (Cu); one or more selected from the group consisting of an amount of more than 0 wt % and about 0.38 wt % or less of vanadium (V) and an amount of more than 0 wt % and about 0.02 wt % or less of niobium (Nb), and iron (Fe) constituting the balance of the weight of the alloy composition, all the wt % based on the total weight of the alloy composition.

6 . A method of manufacturing a bearing steel, comprising:
heat-treating a wire rod comprising an alloy composition, at a temperature of 720 to 850° C. for 4 to 8 hours to spheroidize a complex carbide; wire-drawing the heat-treated wire rod; secondarily heat-treating the wire-drawn wire rod at a temperature of 720 to 850° C. for 4 to 8 hours to spheroidize the complex carbide; forging the secondary heat-treated wire rod to form the bearing steel; and quenching, rapidly cooling, and tempering the formed bearing steel, wherein the alloy composition comprises: based on a total weight of the alloy composition, an amount of about 0.8 to 1.0 wt % of carbon (C), an amount of about 0.35 to 0.9 wt % of silicon (Si), an amount of about 0.5 to 1.0 wt % of manganese (Mn), an amount of about 0.6 to 1.5 wt % of nickel (Ni), an amount of about 1.2 to 1.55 wt % of chromium (Cr), an amount of about 0.2 to 0.5 wt % of molybdenum (Mo), an amount of about 0.01 to 0.06 wt % of aluminum (Al), an amount of about 0.01 to 0.1 wt % of copper (Cu), and iron (Fe) constituting the balance of the weight of the alloy composition.

7 . The method of claim 6 , wherein the alloy composition further comprises one or more selected from the group consisting of an amount of more than 0 wt % and about 0.38 wt % or less of vanadium (V) and an amount of more than 0 wt % and about 0.02 wt % or less of niobium (Nb), all the wt % based on the total weight of the alloy composition.

8 . The method of claim 6 , wherein the quenching is performed at a temperature of 840 to 860° C. for 0.5 to 2 hours, and the tempering is performed at a temperature of 150 to 190° C. for 0.5 to 2 hours.

9 . The method of claim 6 , wherein the complex carbide comprises one or more selected from the group consisting of M 3 C, M 7 C 3 , M 23 C 6 , and MC carbides, wherein M is a metal or a transition metal.

10 . The method of claim 9 , wherein the M of the M 3 C, M 7 C 3 , and M 23 C 6 carbides is one or more selected from the group consisting of chromium (Cr), iron (Fe), and manganese (Mn).

11 . The method of claim 9 , wherein the M of the MC carbide is one or more selected from the group consisting of chromium (Cr), iron (Fe), vanadium (V), niobium (Nb), and molybdenum (Mo).

12 . A vehicle part that comprises an alloy composition of claim 1 .

13 . The vehicle part of claim 12 , wherein the vehicle part is a bearing of an engine or a transmission.

Assignees

• Hyundai Motor Co Ltd

Inventors

• Cha Sung-Chul
• Hong Seung-Hyun

Classifications

• C21D8/06

  during manufacturing of rods or wires · CPC title

• C21D8/00 Primary

  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

• C22C38/06

  containing aluminium · CPC title

• C21D6/004

  containing Cr and Ni · CPC title

• C21D9/36

  for balls; for rollers · CPC title