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Precipitation hardenable austenitic steel

a technology of precipitation hardening and austenitic steel, which is applied in the direction of heat treatment equipment, manufacturing tools, furnaces, etc., can solve the problems of increasing the risk of introducing surface defects in the material, increasing the cost of production process, and affecting the quality of springs, etc., and achieves high silicon content, high strength, and good balance of aluminium.

Inactive Publication Date: 2007-02-22
SANDVIK INTELLECTUAL PROPERTY AB
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0005] Therefore, it is an object of the present invention to provide a high strength, precipitation hardenable, austenitic stainless steel alloy containing a well-balanced amount of aluminium and a high silicon content, a product, which is reduced by cold-working, especially drawing, without an intermediate heat treatment, the strength of which increases by final heat treatment at 300° C. to 500° C. with not less than 14%, which shows shows a Md30-value of between −55 and −100, a loss of force that is lower than 3.0% at 1400 N during 24 hours and which is very suitable for use in spring applications, such as springs of round wire and strip steel and medical applications, such as surgical and dental instruments.

Problems solved by technology

This makes the production process more expensive, as well as increases the risk of introducing surface defects in the material.
The disadvantage of these steels is that the resulting product properties that are essential for a good spring function frequently are worse than for steels of AISI 302 and AISI 631.

Method used

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  • Precipitation hardenable austenitic steel
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  • Precipitation hardenable austenitic steel

Examples

Experimental program
Comparison scheme
Effect test

example 1

Springs of Round Wire

[0039] As been described above, springs of wire made from the alloy according to invention are wound. These springs have good spring properties in the form of relaxation, i.e. the retention of spring force under a long period and are advantageously used in typical spring applications, such as, for instance, springs in locking applications, i.e. mechanical parts in the locking device, springs in aerosol containers, pens, especially ball point pens, pump springs, springs in industrial looms, springs in the vehicle industry, electronics, computers and fine mechanics.

example 2

Springs of Strip Steel

[0040] For plane torsion springs, the torque is a decisive quantity. The torque can be expressed as M=E*I*2*π⁡(n-n0)L

where:

M=the torque of the spring

I=moment of bending inertia (b*t3 / 12)

B=spring strip width

T=spring strip thickness

L=extended spring length

no=number of turns at free spring (unmounted)

n=number of working turns

[0041] In order to increase the torque at a given spring geometry, a so-called reverse winding may be accomplished. At a so-called “resilient” winding, the spring is preformed by being wound in a direction opposite the working direction. Then a heat treatment of the spring takes place, after which it is wound-in in the opposite direction in the spring housing. At so-called “cross curve” winding, the strip is formed on a tack, after which heat treatment takes place. Then the spring is wound in the opposite direction into the spring housing. By means of this procedure, a lower and sometimes even a negative value of n0 can be ob...

example 3

Expander Wire

[0042] An expander is a bit of wire, which is corrugated and shaped to a flat spring connected in series. This spring is used, for instance, in order to regulate the pressure of the oil scraper rings against the cylinder wall in an internal combustion engine. A typical expander for car motors is seen as the corrugated wire between two piston rings. A possible embodiment of such a corrugated ring is shown schematically in FIG. 4.

[0043] A drawback of motor-driven vehicles today is the great energy consumption that is necessary in order to give the vehicle the desired performance thereof. The easiest ways to achieve a reduced energy consumption is, among other things, to diminish the internal friction of the drive and to reduce the total mass of the vehicle. The piston core accounts for more than half of the friction of a motor. Therefore, it is a continuous aim to improve the material and precision of the rings, pistons and cylinder walls with the purpose of reducing ta...

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Abstract

The present invention relates to a stainless steel alloy, more precisely a highstrength stainless, precipitation hardenable, austenitic, stainless alloy, containing a well adjusted amount of aluminium and a high silicon content and which has the following composition (in weight-%): C 0-0.07 Si 0.5-3.0 N 0-0.1 Cr 15.0-20.0 Ni 7.0-12.0 Al 0.25-1.5 Cu 0<Cu<4.0 Mn 0-3.0 Mo 0-2.0 Ti 0-1.0 and the balance Fe together with normally occurring impurities and additives and a product that is reduced by cold working, especially drawing, without intermediate heat treatment, the strength of which increases by final heat treatment at 300° C. to 500° C. by not less than 14%, that shows a Md30-value of between −55 and −100, a loss of force that is smaller than 3.0% at 1 N during 24 h and which is very suitable for use in spring applications, such as springs of round wire and strip steel and in medical applications, such as surgical and dental instruments.

Description

TECHNICAL AREA OF THE INVENTION [0001] The present invention relates to an austenitic stainless steel alloy, more precisely a high-strength precipitation hardenable austenitic stainless steel alloy containing a well balanced aluminium content and a high silicon content, a product which is reduced by cold working, especially drawing, without intermediate heat treatment, the strength of which increases through final heat treatment at 300° C. to 500° C. by not less than 14%, which shows a Md30-value of between −55 and −100, a loss of force that is lower than 3.0% at 1400 N during 24 hours and which is very suitable for use in spring applications, such as springs of round wire and strip steel and in medical applications, such as surgical and dental instruments. BACKGROUND OF THE INVENTION [0002] On the market for stainless spring steel, the cold-worked austenitic stainless springsteels of type AISI 302 assume a dominating position. This is based on a combination of relatively good corro...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22C38/42C21D9/00C21D8/02C21D9/02C21D9/52C22C38/00C22C38/02C22C38/04C22C38/06C22C38/34C22C38/58
CPCC21D8/0236C21D9/52C22C38/02C22C38/04C22C38/06C22C38/34C22C38/42C22C38/40
Inventor ZETTERHOLM, GUSTAFHOLMBERG, HAKAN
Owner SANDVIK INTELLECTUAL PROPERTY AB