Global Patent Index - EP 0320548 A1

EP 0320548 A1 19890621 - Method of making a duplex stainless steel and a duplex stainless steel product with improved mechanical properties.

Title (en)

Method of making a duplex stainless steel and a duplex stainless steel product with improved mechanical properties.

Title (de)

Verfahren zur Herstellung rostfreien Duplexstahls und Bauteile aus rostfreiem Duplexstahl mit verbesserten mechanischen Eigenschaften.

Title (fr)

Procédé de fabrication d'un acier inoxydable duplex et produit en acier inoxydable duplex, présentant des caractéristiques mécaniques améliorées.

Publication

EP 0320548 A1 19890621 (EN)

Application

EP 87311114 A 19871217

Priority

EP 87311114 A 19871217

Abstract (en)

There is disclosed a method of making a duplex stainless steel for an alloy having the following composition: Carbon 0.001 to 0.08 Wt.% Manganese 0.001 to 2.00 Wt.% Silicon 0.001 to 1.50 Wt.% Chromium 20.00 to 27.50 Wt.% Nickel 8.00 to 11.00 Wt.% Molybdenum 3.00 to 4.50 Wt.% Sulfur 0.0001 to 0.050 Wt.% Phosphorus 0.0001 to 0.050 Wt.% Nitrogen 0.10 to 0.30 Wt.% Iron Balance by selecting a heat treating temperature in the range of about 2050 DEG F to about 2350 DEG F to provide a desired impact toughness and a desired yield strength. There is also disclosed a duplex stainless steel having austenite pools in a ferrite matrix resulting from heating to a temperature in the range of 2050 DEG F - 2350 DEG F and cooling rapidly thereafter, said steel having essentially the above-mentioned composition with the proviso that <MATH> where: Creq = 1.5 (%Cr+%Si+%Mo) Nieq = %Ni+0,3 (%Mn) +%Cu+22(%C) +5%N and having greater impact toughness values in the cast form than Ferralium Alloy 225 and SAF 2205, the impact toughness in Charpy V-notch testing at -100 DEG F being above 75 ft.-lbs. when tested from keel blocks per ASTM E23-82, the HAZ impact toughness at -100 DEG F being above about 50 ft.-lbs. and having a yield strength of at least 65 KSI.

IPC 1-7

C22C 38/44

IPC 8 full level

C22C 38/00 (2006.01); C22C 38/44 (2006.01)

CPC (source: EP)

C22C 38/001 (2013.01); C22C 38/44 (2013.01)

Citation (search report)

Designated contracting state (EPC)

DE FR GB SE

DOCDB simple family (publication)

EP 0320548 A1 19890621; EP 0320548 B1 19920812; DE 3781160 D1 19920917; DE 3781160 T2 19930318

DOCDB simple family (application)

EP 87311114 A 19871217; DE 3781160 T 19871217