Title: Creep resistant high temperature martensitic steel

Abstract

The disclosure provides a creep resistant alloy having an overall composition comprised of iron, chromium, molybdenum, carbon, manganese, silicon, nickel, vanadium, niobium, nitrogen, tungsten, cobalt, tantalum, boron, copper, and potentially additional elements. In an embodiment, the creep resistant alloy has a molybdenum equivalent Mo(eq) from 1.475 to 1.700 wt. % and a quantity (C+N) from 0.145 to 0.205. The overall composition ameliorates sources of microstructural instability such as coarsening of M.sub.23C.sub.6carbides and MX precipitates, and mitigates or eliminates Laves and Z-phase formation. A creep resistant martensitic steel may be fabricated by preparing a melt comprised of the overall composition followed by at least austenizing and tempering. The creep resistant alloy exhibits improved high-temperature creep strength in the temperature environment of around 650.degree. C.

Inventors:

Hawk, Jeffrey A.; Jablonski, Paul D.; Cowen, Christopher J.

Issue Date:

2017-01-31

Research Org.:

National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1342097

Patent Number(s):

9556503

Application Number:

14/871,774

Assignee:

U.S. Department of Energy (Washington, DC)

Patent Classifications (CPCs):

C - CHEMISTRY C21 - METALLURGY OF IRON C21D - MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS

C - CHEMISTRY C22 - METALLURGY C22C - ALLOYS

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C - CHEMISTRY C21 - METALLURGY OF IRON C21D - MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS

C21D2211/004 - Dispersions
C21D2211/008 - Martensite
C21D6/00 - Heat treatment of ferrous alloys
C21D6/002 - {containing Cr
C21D6/02 - Hardening by precipitation
C21D8/00 - Modifying the physical properties by deformation combined with, or followed by, heat treatment
C21D8/005 - {of ferrous alloys
C21D8/0226 - {Hot rolling}
C21D8/0263 - {following hot rolling}

C - CHEMISTRY C22 - METALLURGY C22C - ALLOYS

C22C38/00 - Ferrous alloys, e.g. steel alloys
C22C38/001 - {containing N}
C22C38/002 - {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60}
C22C38/02 - containing silicon
C22C38/04 - containing manganese
C22C38/40 - with nickel
C22C38/44 - with molybdenum or tungsten
C22C38/46 - with vanadium
C22C38/48 - with niobium or tantalum
C22C38/52 - with cobalt
C22C38/54 - with boron

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Resource Type:

Patent

Resource Relation:

Patent File Date: 2015 Sep 30

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE