CN102666906A - Method for increasing the strength of components made of steel under cyclic load - Google Patents
Method for increasing the strength of components made of steel under cyclic load Download PDFInfo
- Publication number
- CN102666906A CN102666906A CN2010800476785A CN201080047678A CN102666906A CN 102666906 A CN102666906 A CN 102666906A CN 2010800476785 A CN2010800476785 A CN 2010800476785A CN 201080047678 A CN201080047678 A CN 201080047678A CN 102666906 A CN102666906 A CN 102666906A
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- component surface
- residual compressive
- compressive stress
- nitride
- nitriding
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/24—Nitriding
- C23C8/26—Nitriding of ferrous surfaces
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Fuel-Injection Apparatus (AREA)
Abstract
The invention relates to a method for increasing the strength of components (1) made of steel, in particular pressurized components of fuel injection systems and/or components of fuel injection systems subjected to high mechanical loads, under cyclic load using residual compressive stresses that are deliberately introduced into the component surface and that counteract the load distribution acting on the component surface during cyclic loads, wherein, according to the invention, a residual compressive stress profile is introduced into the component surface by means of gas nitriding of the component (1) and a nitride bonding layer (3) having a thickness (d) of no more than 10 [mu]m is applied to the component surface during gas nitriding.
Description
Technical field
The present invention relates to the method said type of a kind of claim 1, that improve the bearing capacity of the compression-member be in the steel component under the circulating load condition, especially fuel oil injection system and/or high mechanical load member.
Background technology
The stress range of the compression-member of fuel oil injection system and/or high mechanical load member from simple pulsation tensile stress until periodically drawing-press repeated stress.
The circulation bearing capacity of member is especially relevant with the weave construction and the intensity of selected steel.No matter be to influence the structure of steel, thereby satisfy above-mentioned stress requirement through the change chemical constitution or through thermal treatment.But because high alloying element content and unusual complicated heat treatment process partly, these measure meetings cause disadvantageous high material cost and manufacturing cost.
Another method that is used to improve the circulation bearing capacity is for example through strengthening roll-in or autofrettage, residual compressive stress to be introduced the surface.But depend on method, restriction to some extent on the member geometrical shape.
In addition, known, as heat treating method, can carry out nitriding to steel and handle, change the chemical constitution of marginal layer.This method is used in reality, and demanding marginal layer hardness is to improve abrasive wear resistance.Method commonly used is gas nitriding, salt bath nitriding and plasma nitriding.Constitute by nitride articulamentum on the component surface and the nitride diffusion layer in the member fringe region at this layer that forms usually.At this, generate with so-called nitriding steel about the best result of hardness and tear strength, it also contains high-load nitride and forms agent except having medium C content, like Al, V, Cr.The test of in document, writing down shows; Also can improve vibration strength through nitriding, but should outstanding be characterised in that the thickness that is at least 0.04mm, be used to improve the required and articulamentum that have certain erosion resistance of wear resistance and can cause disadvantageous effect the circulation bearing capacity.
Summary of the invention
The objective of the invention is, a kind of method is provided, can mode with low cost improve the circulation bearing capacity of pulsating load member through said method.Advantage of the present invention
Said purpose is to realize through the method with the said characteristic of claim 1 according to the present invention.
Different with the gas nitriding commonly used that is used for improving marginal layer hardness by the thick as far as possible articulamentum that is at least 0.04mm; According to the present invention, thus adopt gas nitriding with the adjacent marginal layer of component surface in introduce intensity gradient and residual compressive stress distribution pointedly.At this, select the processing parameter of gas nitriding, for example nitriding temperature and nitriding time length, nitrogen concentration etc. are the nitride articulamentum of 10 μ m to the maximum to guarantee on component surface coating thickness.
Through the gas nitriding that articulamentum according to the present invention reduces, can change the marginal layer of steel, thereby can significantly improve the circulation bearing capacity of member.As the replacement scheme with low cost of the traditional measures that improves vibration strength, use of the gas nitriding of the material of non-alloying and low alloying together with process optimization.Show that in addition compare with undressed materials behavior, the articulamentum that thickness is 10 μ m to the maximum has significantly improved the tolerance to salt spray, and does not damage the circulation bearing capacity.The corrosive property of the member of gas nitriding is suitable with parkerized member according to the present invention, therefore can in technology chain, cancel last member and apply.
Improving in the gas nitriding of vibration strength by the articulamentum of minimum according to the present invention, adopting following physics of metals basic principle to come to regulate pointedly the characteristic gradient in the fringe region:
I, the residual compressive stress of regulating in the fringe region through introducing nitrogen in the edge region distribute;
Ii, form nitride and improve intensity in the edge region gradually through diffusion nitrogen;
Iii, raising are to atomospheric corrosion or to corrosive tolerance in the aqueous medium (fuel oil, condensation product).
Regulating residual compressive stress (i) from the teeth outwards is owing to introduce nitrogen in the edge region.On the numerical value for be that positive load tension stress superposes on negative unrelieved stress and the numerical value, thereby the working load that makes the part appearance that is caused is less than the materials behavior without nitriding.Because the work tension stress that this part reduces, postpone or even avoided cracking from the teeth outwards or crackle enlarges.
Therefore, for special member geometrical shape, can improve the vibration strength of high loading member pointedly with mode simple and with low cost.Can make for example circulation bear the combustion engine unit of pressure and/or pulling force thus, can resist the pulsating load that in operational process, occurs like cylinder head, injector, pressure accumulator, valve body etc.At this, need not to reduce or remove the articulamentum that is introduced in component inside in the later stage, minimum because it has been decreased to according to the gas nitriding of process optimization of the present invention the time.
Introduce nitrogen in the edge region and (ii) have equivalence with hardness with the local intensity that improves.At this, according to alloy composition, lip-deep hardness value can be up to 1000HV.
According to FKM (machinofacture research board of supervisors) criterion, draw in principle-press-alternation intensity σ
W, ZDWith static strength R
mHave following relation:
σ
W，ZD＝0.45R
m
For the materials behavior of homogeneous, the raising of bearing capacity roughly is equivalent to the half the of under static stress condition intensity raising amount under the stress alternation condition.In the fringe region that is optimized through the nitriding processing pointedly, improving the circulation bearing capacity can quantize according to the FKM criterion as follows:
σ
W，ZD＝K
v·0.45R
m
Wherein
K
v=1.15 to 1.25, for level and smooth/member of small breach arranged
K
v=1.30 to 2.0, for the breach member.
Therefore, can regulate very high vibration strength characteristic value pointedly through the gas nitriding that articulamentum reduces in the edge region.According to member geometrical shape and base mateiral, can the bearing capacity under the stress alternation condition be improved 25 to 100%.Therefore, according to the absolute value of the load in operational process, can use underlying strength to be lower than the material of the plow-steel that is generally used for the high pressure stress member.Reduce machining cost extraly through reducing matrix hardness.
Compare with other methods that improve vibration strengths, be according to another advantage of gas nitriding of the present invention, in the working temperature that raises but be lower than under the condition of nitriding temperature, be that intensity in the fringe region improves or unrelieved stress all is stable.
Similar with the improvement of passivation layer, corrosive nature improvement (iii) is owing to form the articulamentum of mainly being made up of the nitride of iron.These ε-nitride and γ '-nitride is a stable phase for corrosion process, its with without protection, the surface of exposed metal/bare metal compares, and in water-based and chloride medium, slowed down corrosion reaction significantly.The thickness of articulamentum confirms to suppress the corrosive degree.Regulate the thickness of articulamentum through the technical process in gas nitriding, it guarantees the best between the raising of the improvement of erosion resistance and vibration strength.
Adopt the steel of handling according to the method for the invention especially to belong to following group:
The converted steel of-non-alloying and low alloying
The quenched and tempered steel of-non-alloying and low alloying
-age hardening steel and AFP steel
-nitriding steel
-Thermal-resistance tool steel
-rapid steel.
In order to reach that desired vibration strength improves and for the tolerance of atmosphere and aqueous corrosion; Preferably be higher than about 420 ℃; Especially under the temperature between 480 ℃ and 620 ℃, heat-treat, last the nitriding time length of depending on desired target strength.The nitriding time length can be maximum 96 hours, preferably between 2 and 12 hours.
In order to improve the wear resistance of circulating load ability and member best, with thickness be at least about 0.1mm, the nitride diffusion layer that preferably is at least about 0.3mm introduces in the surface of member.
On the other hand, the invention still further relates to and utilize prepared according to the methods of the invention member, this member to have the described characteristic of claim 5.
Other advantages and the embodiment preferred of theme of the present invention are selected from specification sheets, accompanying drawing and claims.
Embodiment by clear demonstration in the accompanying drawings sets forth the present invention in more detail below.
Description of drawings
Shown in Figure 1 for utilizing prepared according to the methods of the invention example member; And
Shown in Figure 2 is in the hardness of the example member shown in Fig. 1 and unrelieved stress and apart from the graph of a relation of the distance of component surface.
Embodiment
The member 1 that in Fig. 1, schematically shows is formed from steel, especially the compression-member of fuel oil injection system and/or high mechanical load member.In order to improve the bearing capacity of the member 1 that is under the circulating load condition, residual compressive stress is distributed introduce in the component surface pointedly, this residual compressive stress distributes to offset and under the circulating load condition, acts on the load distribution on the component surface.Handle through under the nitriding temperature between about 420 ℃ and about 620 ℃, member being carried out gas nitriding, last the nitriding time length, pointedly residual compressive stress is introduced in the component surface by the gas nitriding of member 1 according to desired target strength.The nitriding time length can be maximum 96 hours, preferably between 2 and 12 hours.
Through gas nitriding, not only nitride diffusion layer 2 is introduced in component surface or the member fringe region, this nitride diffusion layer produces the residual compressive stress that desired intensity improves and requires, but also on component surface nitride coated articulamentum 3.In diffusion layer 2, producing residual compressive stress is owing to introduce (infiltration) nitrogen in the edge region.Articulamentum 3 mainly is made up of the nitride that is deposited on the iron on the component surface.Select the nitridation process parameter,, thereby make the thickness d of nitride articulamentum be 10 μ m to the maximum like nitriding temperature and nitriding time length, nitrogen concentration etc.In contrast, the thickness D of nitride diffusion layer 2 is obviously bigger, and is about 0.3mm in an illustrated embodiment.
As shown in Figure 2; The residual compressive stress ES that introduces in the member 1 through gas nitriding directly is being about 1000MPa on the component surface; And, be transformed into residual tension at the member degree of depth place that is about 0.3mm in the present embodiment until it along with the increase apart from the distance X of component surface descends with exponential manner.In addition, in example member 1, find that on component surface the part improved the intensity of circulation characteristic, be shown as the raising of the hardness H of the directly high from the teeth outwards numerical value to 1000HV at this.The hardness that improve this part descends along with the increase of distance X, and in the present embodiment in the hardness that reaches base mateiral apart from the distance on surface for about 0.3mm place.
Claims (6)
1. improve by residual compressive stress and be in the steel component (1) under the circulating load condition; Especially the method for the bearing capacity of the compression-member of fuel oil injection system and/or high mechanical load member; This residual compressive stress is introduced in the component surface pointedly and offset acts on the load distribution on the component surface under the circulating load condition; It is characterized in that; Handle member (1) by gas nitriding and residual compressive stress is distributed introduce in the component surface, and in the gas nitriding treating processes on component surface coating thickness (d) be the nitride articulamentum (3) of 10 μ m to the maximum.
2. according to the method for claim 1, it is characterized in that the nitride diffusion layer (2) that in the gas nitriding treating processes, will produce residual compressive stress is introduced in the component surface.
3. according to the method for claim 2, it is characterized in that, thickness (D) is at least about 0.1mm, preferably is at least in nitride diffusion layer (2) the introducing component surface of about 0.3mm.
4. according to the method for one of aforementioned claim, it is characterized in that nitriding temperature is higher than about 420 ℃ in the gas nitriding treating processes, preferably between about 480 ℃ and about 620 ℃.
5. steel component (1); Especially the compression-member of fuel oil injection system and/or high mechanical load member; Wherein residual compressive stress is introduced in the component surface pointedly, this residual compressive stress is offset and under the circulating load condition, is acted on the load distribution on the component surface, it is characterized in that; The nitride diffusion layer (2) that produces residual compressive stress is introduced in the component surface, and coating thickness (d) is the nitride articulamentum (3) of 10 μ m to the maximum on component surface.
6. according to the member of claim 5, it is characterized in that the thickness (D) of nitride diffusion layer (2) is at least 0.1mm, preferably is at least about 0.3mm.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE200910045878 DE102009045878A1 (en) | 2009-10-21 | 2009-10-21 | Method for increasing the strength of steel components under cyclic loading |
| DE102009045878.6 | 2009-10-21 | ||
| PCT/EP2010/064062 WO2011047930A1 (en) | 2009-10-21 | 2010-09-23 | Method for increasing the strength of components made of steel under cyclic load |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN102666906A true CN102666906A (en) | 2012-09-12 |
Family
ID=43569208
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010800476785A Pending CN102666906A (en) | 2009-10-21 | 2010-09-23 | Method for increasing the strength of components made of steel under cyclic load |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP2491160A1 (en) |
| CN (1) | CN102666906A (en) |
| DE (1) | DE102009045878A1 (en) |
| WO (1) | WO2011047930A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102015213068A1 (en) | 2015-07-13 | 2017-01-19 | Robert Bosch Gmbh | Process for nitriding a component |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6093263A (en) * | 1997-06-30 | 2000-07-25 | Aisin Aw Co., Ltd. | Soft nitrided gear and method of fabricating the same |
| EP1229143A2 (en) * | 2001-02-02 | 2002-08-07 | Meritor Suspension Systems Company Inc. | Method for surface hardening a steel coil spring |
| JP2007077411A (en) * | 2005-09-09 | 2007-03-29 | Daido Steel Co Ltd | Machine structural component having excellent fatigue strength and wear property, and method for producing the same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002047554A (en) * | 2000-07-28 | 2002-02-15 | Sumitomo Metal Mining Co Ltd | Nitride-layer-coated austenitic iron-base alloy |
| TWI255885B (en) * | 2003-10-27 | 2006-06-01 | Riken Kk | Three-piece type combined oil control ring |
-
2009
- 2009-10-21 DE DE200910045878 patent/DE102009045878A1/en not_active Withdrawn
-
2010
- 2010-09-23 CN CN2010800476785A patent/CN102666906A/en active Pending
- 2010-09-23 EP EP10759620A patent/EP2491160A1/en not_active Ceased
- 2010-09-23 WO PCT/EP2010/064062 patent/WO2011047930A1/en active Application Filing
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6093263A (en) * | 1997-06-30 | 2000-07-25 | Aisin Aw Co., Ltd. | Soft nitrided gear and method of fabricating the same |
| EP1229143A2 (en) * | 2001-02-02 | 2002-08-07 | Meritor Suspension Systems Company Inc. | Method for surface hardening a steel coil spring |
| JP2007077411A (en) * | 2005-09-09 | 2007-03-29 | Daido Steel Co Ltd | Machine structural component having excellent fatigue strength and wear property, and method for producing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| DE102009045878A1 (en) | 2011-04-28 |
| EP2491160A1 (en) | 2012-08-29 |
| WO2011047930A1 (en) | 2011-04-28 |
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Application publication date: 20120912 |