Duplex stainless steel alloy and use of this alloy

Inactive Publication Date: 2010-12-16
SANDVIK INTELLECTUAL PROPERTY AB
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  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0010]The object of the present invention is to provide a duplex stainless steel alloy of the type defined above and especially in the European patent 0 683 241, which has improved properties, especia

Problems solved by technology

However, this alloy as well as the alloys discussed above is highly susceptible to intermetallic precipitation, especially sigma phase precipitation, which makes the materia

Method used

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  • Duplex stainless steel alloy and use of this alloy

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Embodiment Construction

[0024]Good corrosion resistance properties as well a high ductility and toughness is obtained by the combination of elements in a duplex stainless steel alloy according to the invention. This steel alloy has also good workability, which enables for example extrusion to seamless tubes. The alloy according to the invention contains (in weight-%):

Cmax 0.03%SiMn  0-3.0%Pmax 0.030%Smax 0.050%Cr25-29%Ni5-9%Mo4.5-8%  W0-3%Cu0-2%Co0-3%Ti0-2%Al  0-0.05%B  0-0.01%Ca  0-0.01%N0.35-0.60%

balance Fe and normal occurring impurities, wherein the ferrite content is 30-70 volume-%, and wherein each weight-% of Mo above may optionally be replaced by two (2) weight-% W.

[0025]Carbon (C) has limited solubility in both ferrite and austenite. The limited solubility implies a risk of precipitation of chromium carbides and the content should therefore not exceed 0.03 weight-%, preferably not exceed 0.02 weight-%.

[0026]Silicon (Si) is utilized as desoxidation agent in the steel production and it increases the...

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Abstract

The present invention relates to a duplex stainless steel alloy containing in weight-%: C max 0.03%, Si<0.30%, Mn 0-3.0%, P max 0.030%, S max 0.050%, Cr 25-29%, Ni 5-9%, Mo 4.5-8%, W 0-3%, Cu 0-2%, Co 0-3%, Ti 0-2%, Al 0-0.05%, B 0-0.01%, Ca 0-0.01%, and N 0.35-0.60%, balance Fe and normal occurring impurities, wherein the ferrite content is 30-70 volume-%, and wherein each weight-% of Mo above may optionally be replaced by two (2) weight-% W.

Description

TECHNICAL FIELD OF THE INVENTION[0001]The present invention relates to a duplex stainless steel alloy, which is a steel alloy having a ferritic-austenitic matrix and especially high resistance to corrosion in combination with good structural stability and hotworkability. The ferrite content is 30-70 volume-% and such steel alloys have a well balanced composition, which imparts the material corrosion properties, which make it suitable for use in for instance chloride-containing environments, such as in the sea.BACKGROUND OF THE INVENTION AND PRIOR ART[0002]Over the recent years, the environments in which corrosion resistant metallic materials were used became more aggressive and the requirements on the corrosion properties as well as on their mechanical properties increased. Duplex steel alloys, which were established as an alternative to other steel grades used until then, for example high alloyed austenitic steels, nickel-base alloys or other high alloyed steels, were also a part o...

Claims

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Application Information

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IPC IPC(8): C22C38/44C22C38/52
CPCC22C38/44
Inventor GORANSSON, KENNETH
Owner SANDVIK INTELLECTUAL PROPERTY AB
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