Cold-formable chrome steel

a chrome steel, cold-formable technology, applied in heat treatment furnaces, heat treatment equipment, furnaces, etc., can solve the problems of poor machining properties of cold-formable and corrosion-resistant ferritic chrome steels, poor machining properties, and splintering of edges, so as to achieve the effect of improving material properties

Inactive Publication Date: 2005-10-06
STAHLWERK ERGSTE WESTIG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0018] A chrome steel according to the present invention is suitable because of its cold-formability and machining capabilities, in particular its excellent metal-cutting properties, its homogeneous structure and the homogeneous distribution of the precipitate phases after cold-forming and following annealing with controlled cool-down, for the manufacture of printer nozzles, tips for writing implements, injection nozzles for chemical and electronic devices, spinnerets, as well as other articles of small dimensions and / or recesses, in particular bore holes.

Problems solved by technology

Without the implementation of special alloying procedures, cold-formable and corrosion-resistant ferritic chrome steels have poor machining properties, mostly due to sticking and welding that occurs during machining in the region of sharp tool edges.
The cutting edge can then become jagged and can splinter, the tool may wear poorly, and the surface quality of the machined workpieces may be poor.
Sticking and welding may also be detrimental when using stamping and forming tools, because these processes occur predominantly in the region of high surface pressure, thus diminishing the surface quality of the machined workpieces and shortening the service life of the tools.
This increases the risk that during micro-machining, for example when drilling bore holes, grooves and recesses with small to extremely small dimensions, the tool, for example a drill, runs off center, caused by the local concentration of hard precipitate phases, thus causing substantial deviations in the final dimensions.
Even the use of micro-tools or drills made of high-grade hard metals, for example with a diameter of less than 0.8 mm, cannot prevent tool runoff, because the tool is diverted from the predetermined machining direction by regions of high concentration of structural carbide components.
However, the relatively high silicon, aluminum and titanium content in the steel produces hard oxide inclusions which causes severe wear during precision machining.
Disadvantageously however, lead has a very low melting point and therefore does not form stable compounds or precipitates.

Method used

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Examples

Experimental program
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Effect test

example 1

[0057] After an etching step, a bare wire having the composition E2 with a diameter of 6 mm was initially subjected to a 3-stage cold-forming process producing a total deformation of 85%. The wire was then annealed in an inert gas atmosphere for 30 minutes at a temperature T1=840° C. (see FIG. 5, curve 3) and thereafter controllably cooled down over 120 minutes to a temperature of T2=600° C.. During the cool-down step, an intermediate 15 minute intermediate heating step was applied twice at respective temperatures of 760° C. and 680° C., while maintaining a constant temperature, to attain a stepped cool-down for stabilizing the precipitates (see FIG. 5, curve 4a).

[0058] After the controlled cool-down, the wire was cooled in air (see FIG. 5, upper curve 5) without supplying additional energy and thereafter sized, which resulted in a deformation of 15%. Sizing was followed by a 15 minute final annealing or tempering at 340° C.. The wire had an excellent machinability with micro-tools...

example 2

[0059] A bare wire having the composition E3 and a diameter of also 6 mm was subjected to a 3-stage cold-forming process producing a total deformation of 80%. The wire was then annealed in an inert gas atmosphere for 35 minutes at a temperature of T1=900° C. (see FIG. 5, curve 3) and then controllably cooled down over 160 minutes at a constant cooling rate, while supplying a small amount of energy, to a temperature T2=620° C. (see FIG. 5, curve 4). The wire was then further down cooled in air to room temperature (see FIG. 5, lower curve 5). The wire was then sized with a deformation of 20% and soaked for 30 minutes at 280° C. and subjected after soaking to micro-cutting, yielding the results listed in Table II.

[0060] The cutting performance was experimentally tested by drilling with a hard alloy drill bit with a diameter of 0.6 mm. The following tests where performed: [0061] The machining characteristic was evaluated based on the straightness of the bore hole and assigned a paramet...

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Abstract

A cold-formable, corrosion-resistant chrome steel includes, by weight percent, 14% to 20% chromium, 0.005% to 0.05% carbon, up to 0.01% nitrogen, 0.2% to 0.6% silicon, 0.3% to 1.0% manganese, 0.1% to 1.0% molybdenum, up to 0.8% nickel, 0.2% to 1.0% copper, 0.15% to 0.65% sulfur, as well as separately or in combination 0.01% to 0.1% lead, 0.01% to 0.5% bismuth, 0.01% to 0.1% arsenic, 0.01% to 0.1% antimony, 0.005% to 0.08% of each of vanadium, titanium, niobium, and zirconium, 0.02% to 0.2% of each of selenium and tellurium, the remainder iron and incidental smelting-related impurities.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS [0001] This application claims the priority of German Patent Applications, Serial Nos. 10 2004 015 992.0-24, filed Apr. 1, 2004, and 10 2004 063 161.1, filed Dec. 29, 2004, pursuant to 35 U.S.C. 119(a)-(d). BACKGROUND OF THE INVENTION [0002] The present invention relates to a cold-formable chrome steel with a ferritic structure. [0003] Nothing in the following discussion of the state of the art is to be construed as an admission of prior art. [0004] Without the implementation of special alloying procedures, cold-formable and corrosion-resistant ferritic chrome steels have poor machining properties, mostly due to sticking and welding that occurs during machining in the region of sharp tool edges. The cutting edge can then become jagged and can splinter, the tool may wear poorly, and the surface quality of the machined workpieces may be poor. [0005] Sticking and welding may also be detrimental when using stamping and forming tools, because thes...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): C21D8/00C22C38/18C22C38/20C22C38/22
CPCC21D6/002C21D7/02C21D8/0236C21D9/0068C22C38/002C22C38/004C22C38/007C22C38/02C22C38/04C22C38/42C22C38/44C22C38/46C22C38/50C22C38/60Y10T428/12
InventorPACHER, OSKARKLOSS-ULITZKA, GISBERTNICOLINI, GUIDO
OwnerSTAHLWERK ERGSTE WESTIG