Austenitic heat-resistant cast steel and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-10626487-B2
Application number	US-201414778352-A
Country	US
Kind code	B2
Filing date	Mar 18, 2014
Priority date	Mar 22, 2013
Publication date	Apr 21, 2020
Grant date	Apr 21, 2020

Abstract

An austenitic heat-resistant cast steel includes 0.1% to 0.6% by mass of C, 1.0% to 3.0% by mass of Si, 0.5% to 1.5% by mass of Mn, 0.05% by mass or less of P, 0.05% to 0.3% by mass of S, 9% to 16% by mass of Ni, 14% to 20% by mass of Cr, 0.1% to 0.2% by mass of N, and the balance of iron and inevitable impurities, in which a matrix structure of the austenitic heat-resistant cast steel is composed of austenite crystal grains, and a ferrite phase is dispersed and interposed between the austenite crystal grains so as to cover the austenite crystal grains.

First claim

The invention claimed is:

1. An austenitic heat-resistant cast steel consisting of:
0.1% to 0.6% by mass of C,
1.0% to 3.0% by mass of Si,
0.5% to 1.5% by mass of Mn,
0.05% by mass or less of P,
0.05% to 0.3% by mass of S,
14% to 20% by mass of Cr,
9% to 16% by mass of Ni,
0.1% to 0.2% by mass of N,
optionally 1.0% to 3.0% by mass of Cu, and
the balance of iron and inevitable impurities,
wherein a matrix structure of the austenitic heat-resistant cast steel is composed of austenite crystal grains, a ferrite phase is dispersed and interposed between the austenite crystal grains so as to cover the austenite crystal grains, and an area ratio of the ferrite phase is in a range of 1 to 10% with respect to a whole structure of the austenitic heat-resistant cast steel.

2. The austenitic heat-resistant cast steel according to claim 1 , wherein 1.0% to 3.0% by mass of Cu is present.

3. A method of manufacturing an austenitic heat-resistant cast steel comprising the steps of:
casting a cast steel from a molten metal consisting of 0.1% to 0.6% by mass of C, 1.0% to 3.0% by mass of Si, 0.5% to 1.5% by mass of Mn, 0.05% by mass or less of P, 0.05% to 0.3% by mass of S, 14% to 20% by mass of Cr, 9% to 16% by mass of Ni, 0.1% to 0.2% by mass of N, optionally 1.0% to 3.0% by mass of Cu, and the balance of iron and inevitable impurities; and
heat treating the cast steel under heating conditions of a heating temperature of 700° C. to 800° C. and a heating time period of 20 to 300 hours to obtain the austenitic heat-resistant cast steel,
wherein a matrix structure of the austenitic heat-resistant cast steel is composed of austenite crystal grains, a ferrite phase is dispersed and interposed between the austenite crystal grains so as to cover the austenite crystal grains, and an area ratio of the ferrite phase is in a range of 1 to 10% with respect to a whole structure of the austenitic heat-resistant cast steel.

4. The method of manufacturing an austenitic heat-resistant cast steel accordingly to claim 3 , wherein the austenitic heat-resistant cast steel exhibits a thermal expansion coefficient of from 16.0 K −1 to 16.2 K −1 , a tensile strength of 110 MPa to 142 MPa, and a fatigue life of 237 times to 295 times.

Assignees

• Ohtake Kazumi
• Ueda Takamichi
• Genma Yoshikazu
• Sato Takahiro
• Fujii Hiroshi
• Toyota Motor Co Ltd
• Aisin Takaoka Ltd

Inventors

• Ohtake Kazumi
• Ueda Takamichi
• Genma Yoshikazu
• Sato Takahiro
• Fujii Hiroshi

Classifications

• C21D2211/001

  Austenite · CPC title

• C22C38/001

  containing N · CPC title

• B22D23/00

  Casting processes not provided for in groups B22D1/00 - B22D21/00 (making metallic powder by casting B22F9/08; alumino-thermic welding B23K23/00; remelting metals C22B9/16) · CPC title

• C22C38/42 Primary

  with copper · CPC title

• C22C38/60

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