DE102007047016A1 - Inexpensive, high-strength, martensitically hardenable steel, useful for producing automobile fuel injector components, has low alloying element content and is free of cobalt - Google Patents

Abstract

Novel high-strength, martensitically hardenable steels (i.e. maraging steels) (I) have an alloying element content of less than 15% and a cobalt content of 0%. An independent claim is included for components of (I), which are formed from rod material having a wall thickness of at least 2.5 mm (especially at least 5 mm).

Description

The The invention relates to a high-strength, martensitaushärtbaren Steel according to the closer in the preamble of claim 1 defined type and a component formed from it, in particular a fuel injection component of a motor vehicle.

State of the art

High-strength, martensitic hardenable steels, which are also used as maraging steels are widely known and used in practice for Applications with highest strength requirements used, wherein maraging steels in addition to a high strength advantageously also good toughness with cheap processing and welding properties. The high strength and good ductility is achieved by these steels Formation of a lancet martensite with intermetallic excretion reached.

Examples of maraging steels are in the US Pat. No. 6,475,307 B1 and the DE 39 33 782 A1 described.

These well-known maraging steels have as well as from practice known maraging steels a high alloy content of usually over 30% by weight, with alloying additions from high-priced metals such as cobalt in the well-known maraging steels disadvantageously lead to high material costs.

Farther It has been shown that the known high-strength, martensitaushärtbaren Steels their typical properties only with sheet metal, which due to the small wall thickness comparatively homogeneous cool, show.

Disclosure of the invention

Technical task

task the invention is to provide a low-cost high-strength, martensitaushärtbaren steel to create, which also for Use with highly stressed components with larger components Wall thickness, in particular in components of motor vehicle fuel injection systems, suitable is.

Technical solution

The Task is starting from the preamble in conjunction with the characterizing Characteristics of claim 1 solved. Advantageous developments are the subject of dependent claims.

To The teaching of the invention is called in the task Problem by a new composition of a high-strength, martensitaushärtbaren Steel solved. This is characterized by the fact that the Total content of alloying elements in the steel less than is about 15% by weight and the alloy is free of cobalt.

Advantageous effects

With the new composition of a high-strength, martensitaushärtbaren Steel makes you realize the knowledge that such a maraging steel with a comparatively low alloy content of at most 15% by weight and without cobalt one for a wide range of applications has sufficient tensile strength of more than 1500 MPa, so this Steel with martensitic structure and intermetallic Excretions almost strength values of maraging steels achieved with a threefold higher alloy content.

Consequently is due to the reduction of the alloy content and in particular the Substitution of cobalt significantly lowered the price of materials and an economical production of components and components with increased mechanical and cyclic stresses this steel possible. Such a steel, which also for Autofrettage is optimized and thus increased fatigue properties has a carbon content of at most 0.04%, a manganese content of at most 4%, a nickel content not more than 12%, a maximum silicon content 2%, a maximum titanium content of 1.8%, a chromium content of maximum 5%, maximum aluminum content 0.3% and a molybdenum content of 4% or less on.

It It has been shown that such a steel is very suitable as a rod material is, that is, the steel has a wall thickness which is larger than that for cold rolling suitable sheet material, in which the material properties also in the middle of the wall thickness by outer Cooling processes are well adjustable, is.

One Maraging steel according to the in the subclaims described advantageous developments of the invention is in terms his chemistry chosen so that he also at one opposite sheets slowed down cooling even in much larger Wall thicknesses in the middle still the desired Features.

Since the cold workability of components with a thickness of more than 2 mm is severely limited, the steel according to the invention is particularly suitable for components, in particular motor vehicle components, with a wall thickness of at least 2.5 mm and in particular with a wall thickness greater than 5 mm. It has been shown that the advantageous properties of the steel according to the invention are also achieved in components of a rod material having a thickness of at least 12 mm and in particular highly stressed components with a wall thickness of at least 25 mm.

components with a high wear stress and high mechanical and cyclic stresses involving the steel of the invention is particularly suitable to provide fuel injection components of a Motor vehicle, which is used both for the injection of diesel as can also be designed by gasoline.

Kraftstoffeinspritzkomponeten represent forged and mostly machined components, which is especially due to the high internal cyclical pressures are claimed. To achieve this necessary Strength is a final thermal aging suitable for precipitation hardening.

A Heat treatment, with no significant distortion of the components occurs and thus a rework is unnecessary, can Solution annealing at about 800 ° C for about one hour and a subsequent aging at approx. 500 ° C for one of the desired target strength provide for a dependent period.

in the The following are four examples of preferred compositions of a maraging steel according to the invention, wherein the ingredients are each given in weight%.

at In a first preferred example, the maraging steel has one Carbon content of at most 0.04%, a manganese content not more than 4%, with a maximum nickel content 3%, a silicon content of at most 2% and a titanium content of not more than 1%.

This As rod material particularly preferred maraging steel has in its Alloy neither a content of cobalt, nor chrome, aluminum or molybdenum on.

One sees second example of a maraging steel according to the invention a maximum carbon content of 0.04%, a manganese content of not more than 2%, a maximum nickel content 1%, a chromium content of at most 2% and a molybdenum content of not more than 1%.

In In this case, the alloy is free of silicon, aluminum and cobalt.

at a third example of a maraging steel according to the invention this has a maximum carbon content of 0.04%, a manganese content of at least 0.15% up to a maximum of 0.4%, a nickel content of not more than 12%, a titanium content of not more than 1,8% and an aluminum content of 0.3%.

The Alloy is free of silicon, chromium, molybdenum and cobalt.

According to one fourth example of a maraging steel according to the invention this maximum carbon content of 0.04%, one Nickel content of not more than 12%, a manganese content of at least 0.15% to at most 0.4%, a titanium content of at most 1.8%, a chromium content of at most 5%, an aluminum content of at most 0.3% and a Molybdenum content of not more than 4%.

This Alloy is also zugegegben neither silicon nor cobalt.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 6475307 B1 [0003]
• - DE 3933782 A1 [0003]

Claims (11)

High-strength, martensite-hardenable steel, characterized by a proportion of alloying elements of less as about 15% with a cobalt content of 0%. High-strength, martensite-hardenable steel according to claim 1, characterized by a carbon content of at most about 0.04%, a manganese content of not more than 4%, with a maximum nickel content 12%, a silicon content of at most 2%, a titanium content of at most 1.8%, a chromium content of at most 5%, an aluminum content of at most 0.3% and a Molybdenum content of 4% or less. High-strength, martensite-hardenable steel according to claim 1, characterized by a carbon content of at most 0.04%, a manganese content of at most 4%, a nickel content of at most 3%, a silicon content not more than 2% and a maximum titanium content 1%. High-strength, martensite-hardenable steel according to claim 1, characterized by a carbon content of at most 0.04%, a manganese content of at most 2%, a nickel content of at most 1%, a chromium content of not more than 2% and a molybdenum content of at most 1%. High-strength, martensite-hardenable steel according to claim 1, characterized by a carbon content of at most 0.04%, a manganese content of at least 0.15% up to a maximum of 0,4%, a maximum nickel content 12%, a maximum titanium content of 1.8% and an aluminum content of at most 0.3%. High-strength, martensite-hardenable steel according to claim 1, characterized by a carbon content of at most 0.04%, a manganese content of at least 0.15% up to a maximum of 0,4%, a maximum nickel content 12%, a maximum titanium content of 1.8%, a chromium content of not more than 5%, an aluminum content of not more than 0.3% and a molybdenum content of at most 4%. Component, in particular motor vehicle component from a high strength martensitic hardenable steel after one of claims 1 to 6, characterized in that it from a rod material with a wall thickness of at least 2.5 mm, in particular of at least 5 mm. Component according to claim 7, characterized that it is made of a rod material with a wall thickness of at least 10 mm, in particular of at least 25 mm, is formed. Component according to claim 7 or 8, characterized it is a fuel injection component of a motor vehicle forms. Component according to one of claims 7 to 9, characterized in that it is heat treated. Component according to one of claims 7 to 10, characterized in that it is autofrettiert.