CN104792617A - Characterization method of mechanical properties of elastic-plastic graded modification layer on metal surface - Google Patents
Characterization method of mechanical properties of elastic-plastic graded modification layer on metal surface Download PDFInfo
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- CN104792617A CN104792617A CN201510164286.1A CN201510164286A CN104792617A CN 104792617 A CN104792617 A CN 104792617A CN 201510164286 A CN201510164286 A CN 201510164286A CN 104792617 A CN104792617 A CN 104792617A
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- elastoplasticity
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Abstract
The invention discloses a characterization method of mechanical properties of an elastic-plastic graded modification layer on a metal surface and belongs to the field of characterization of properties of modification layers on metal surfaces. According to the method, a plasma surface alloying method is adopted for a polished metal base material, infiltration elements are selected reasonably, and the elastic-plastic graded modification layer is formed on the surface of the polished metal base material. Butt bonding, sample inlaying and polishing treatment are performed on cut and prepared sample cross sections. The modification layer is divided into multiple sub-layers according to the thickness of the modification layer and the indentation contact radius for a nano-indentation test. Inverse analysis calculation is performed on a load-displacement curve obtained through test of each sub-layer with ANSYS v10.0 finite element software, and the elastic-plastic property parameter of each sub-layer is obtained. Mechanical property parameters of all the sub-layers are numerically fitted, so that mechanical property parameters of all points in the thickness direction of the elastic-plastic graded modification layer on the metal surface are obtained quantitatively. The method is easy to operate, besides, the matrix effect is eliminated, and the result is accurate and reliable.
Description
Technical field
The present invention relates to the characterizing method of a kind of metal surface elastoplasticity gradient modified layer mechanical property, belong to metal surface modification layer mechanical property representational field.
Background technology
The various performances such as metal surface modification effectively can improve the resistance to wearing of metal surface, is out of shape, fatigue, corrosion.Therefore, from ancient times to the present, metal surface modification is widely used at industry-by-industry.Compare to homogeneous modified layer, gradient modified layer has two large advantages: one is there is not obvious interface problem, the spalling failure that can effectively avoid interface weakens to cause; Two is have good compatibility of deformation ability, can bear higher quiet/dynamic Contact load, to softer metals such as titanium alloys, there is important using value.
Current gradient modified layer is mainly by its mechanical property of composite hardness qualitative characterization, but actual problems faced is, only has the Elastoplastic Performances in Simulation parameter of quantitatively trying to achieve gradient modified layer, just by stress, the strain regime of inside workpiece under the quiet/dynamic Contact condition of finite element forward analysis investigation, set up its corresponding inefficacy mechanism, and then provide theoretical reference for the design of modified layer and engineer applied.At Analysis of instrumented indentation test data for functionally graded materials, Surface & Coatings Technology, 2003, 168 (2): 136-141 and Mechanics of indentation of plastically gradedmaterials-I:Analysis, Journal of the Mechanics and Physics ofSolids, 2008, the general constitutive equation setting up gradient modified layer is mentioned in 56 (1): 157-171., but mathematic(al) simplification is too much, and it is loaded down with trivial details to derive, not there is applicability to elastoplasticity gradient modified layer, tension gradient effect can only be applicable to obviously or the obvious material of plasticity Gradient Effect.
Summary of the invention
The present invention aims to provide the characterizing method of a kind of metal surface elastoplasticity gradient modified layer mechanical property, by carrying out sticky edge sample to elastoplasticity gradient modified layer xsect, layered shaping, nanometer press-in test, finite element inversion analytical calculation and numerical fitting can quantitatively obtain its mechanical property parameters, thus avoid surface directly to measure the matrix effect that causes or the non-chamfering effect of sticky edge sample being tested to existence of xsect, and the mistake simplicity brought of pure mathematical model and non-versatility.
The invention provides the characterizing method of a kind of metal surface elastoplasticity gradient modified layer mechanical property, adopt the characterization method that nanometer press-in test and finite element analogy combine.
First this characterizing method carries out xsect to sticky edge sample for the sample of preparation, then according to the size of modified layer thickness and impression contact radius, its layering is characterized separately, the mechanical property parameters of each layer of last numerical fitting, thus the mechanical property parameters quantitatively obtaining each point on the elastoplasticity gradient modified layer thickness direction of metal surface.
Characterizing method provided by the invention comprises the following steps:
(1) metal base pre-service: size elects Ф 18mm × 5mm as, carries out polishing to its surface;
(2) prepare elastoplasticity gradient modified layer: by plasma surface alloying method, reasonably select to infiltrate element, form high rigidity, wear-resistant and corrosion resistant elastoplasticity gradient modified layer in metallic substrate surface; The technological parameter optimized is: die opening, and the distance namely between target and specimen surface, is set to 18mm, and operating air pressure is 40Pa, and source electrode negative bias is-660 ~-900V, and workpiece pole negative bias is-300 ~-650V, and technological temperature is 900 DEG C, and temperature retention time is 3h;
(3) to sticky edge sample: the xsect sample cut two first to sticking together, and then carries out edge sample, to the xsect sample inlayed, polishing is carried out;
(4) layering simplifies: according to the thickness of elastoplasticity gradient modified layer and the size of impression contact radius a, according to the rule of indent spacers △ l >=2a, modified layer is divided into some sublayers, thus makes elastoplasticity gradient modified layer be reduced to the form of elastoplasticity gradient layers;
(5) nanometer is utilized to be pressed into the Elastoplastic Performances in Simulation parameter of test in conjunction with the every one deck of finite element analogy quantitatively characterizing: nanometer press-in test selects the nanometer press fit instrument of band built-in scan probe microscope to carry out, the number of test points of each sublayer is no less than 5, and test load elects 8mN as; Utilize the load-displacement curves of ANSYSv10.0 finite element software to each sublayer test gained to carry out reverse calculation, obtain the Elastoplastic Performances in Simulation parameter of each sublayer;
(6) utilize the Elastoplastic Performances in Simulation parameter of Matlab6.5 to each sublayer to carry out curve fitting, fit equation selects following polynomial expression:
y＝a+b
1x+b
2x
2+…b
kx
k
In formula, a, b
1, b
2... b
kfor fitting parameter.Utilize the functional relation of matching, can the mechanical property parameters of each point on the elastoplasticity gradient modified layer thickness direction of quantitative solving metal surface.
In above-mentioned characterizing method, the concrete steps of described step (1) and (3) middle polishing are: first adopt SiC emery paper to polish, then the diamond polishing spray of 0.5 μm is adopted to carry out polishing, until surface roughness Ra <0.1 μm; After polishing, for subsequent use after using pure water, acetone ultrasonic cleaning successively.
In above-mentioned characterizing method, infiltrate element in described step (2) and select according to the intermetallic mutual solubility of metal phase diagram.
In above-mentioned characterizing method, in described step (2), the technological parameter of plasma surface alloying method is: die opening is set to 18mm, operating air pressure is 40Pa, source electrode negative bias is-660 ~-900V, workpiece pole negative bias is-300 ~-650V, technological temperature is 900 DEG C, and temperature retention time is 3h.
In above-mentioned characterizing method, in described step (4), the thickness h of each sublayer is equal and satisfied: h >=4a.
In above-mentioned characterizing method, in described step (5), the concrete steps of nanometer press-in test are: nanometer press-in test selects the nanometer press fit instrument of band built-in scan probe microscope to carry out, the number of test points of each sublayer is no less than 5, and test load elects 8mN as.
In above-mentioned characterizing method, in described step (5), the concrete steps of finite element analogy are: utilize the load-displacement curves of ANSYSv10.0 finite element software to each sublayer test gained to carry out back analysis calculating, obtain the Elastoplastic Performances in Simulation parameter of each sublayer.
Beneficial effect of the present invention: adopt the inventive method can avoid directly testing to specimen surface the matrix effect or the non-chamfering effect existed the test of sticky xsect edge sample that cause, thus realize the mechanical property parameters (elastic modulus, yield stress and work-hardening exponential) of quantitatively characterizing metal surface elastoplasticity gradient modified layer fast and effectively.
Accompanying drawing explanation
Fig. 1 is that after pure Ti oozes Mo, elastoplasticity gradient modified layer xsect, to sticky edge master drawing, is recorded by scanning probe microscopy (SPM).
Fig. 2 is the remaining impression figure after pure Ti oozes the layering nanometer press-in test of Mo gained elastoplasticity gradient modified layer, is recorded by scanning probe microscopy (SPM).
Fig. 3 is the matched curve of Mo elastoplasticity gradient modified layer elastic modulus E.
Fig. 4 is Mo elastoplasticity gradient modified layer yield stress σ
ymatched curve.
Fig. 5 is the matched curve of Mo elastoplasticity gradient modified layer work-hardening exponential n.
Embodiment
Further illustrate the present invention below by embodiment, but be not limited to following examples.
Embodiment:
Now ooze the elastoplasticity gradient modified layer of Mo formation for pure Ti surface, the present invention implemented, as Fig. 1 ~ Fig. 5 can show:
(1) first model is adopted to be 320,600,800,1000,1500,2000,2500 and 3000 object SiC emery papers are polished step by step to Ti base material (Ф 18mm × 5mm), secondly the diamond polishing spray of 0.5 μm is adopted to carry out polishing, until surface roughness Ra <0.1 μm.After polishing, for subsequent use after using pure water, acetone ultrasonic cleaning successively;
(2) by plasma surface alloying method, ooze Mo on pure Ti surface and form high rigidity, wear-resistant and corrosion resistant elastoplasticity gradient modified layer.The technological parameter optimized is: die opening, and the distance namely between target and specimen surface, is set to 18mm, and operating air pressure is 40Pa, and source electrode negative bias is-660 ~-900V, and workpiece pole negative bias is-300 ~-650V, and technological temperature is 900 DEG C, and temperature retention time is 3h;
(3) adopt Mo wire cutting machine cutting sample and carry out, to sticky edge sample, taking the step described in (1) to carry out polishing equally for the xsect sample inlayed.To the sample after sticky as shown in Figure 1, the resin (resin) in the middle of sample is caused by high temperature edge sample.Have identical character to sticky two parts, wherein any part can be selected to characterize, and this example selects the right half part of Fig. 1 to characterize.
(4) according to the thickness 9.6 μm of Mo elastoplasticity gradient modified layer, the impression contact radius 0.7 μm that 8mN is corresponding, modified layer is divided into three sublayers and carries out nanometer press-in test, 5 points are tested in each sublayer, as shown in Figure 2;
(5) utilize the load-displacement curves of ANSYSv10.0 finite element software to each sublayer nanometer press-in test gained to carry out back analysis calculating, obtain the Elastoplastic Performances in Simulation parameter of each sublayer, see the discrete data point in Fig. 3 ~ Fig. 5;
(6) utilize the Elastoplastic Performances in Simulation parameter of Matlab6.5 to each sublayer to carry out curve fitting, fit equation selects following polynomial expression:
y＝a+b
1x+b
2x
2+…b
kx
k
In formula, a, b
1, b
2... b
kfor fitting parameter.
Fig. 3 is elastic modulus E and the curve map apart from specimen surface thickness x (0≤x≤9.6 μm), discrete data point known in figure draws from step (5), according to the value of known point x, E, through over-fitting, obtain the distribution curve of elastic modulus E on Mo elastoplasticity gradient modified layer thickness direction and corresponding functional relation:
E＝67.33+203.18x-82.81x
2+15.32x
3-1.37x
4+0.05x
5
Fig. 4 is yield limit σ
ywith the curve map apart from specimen surface thickness x, through the matching to discrete data point, obtain yield limit σ on Mo elastoplasticity gradient modified layer thickness direction
ydistribution curve and corresponding functional relation:
σ
y＝-0.24+4.74x-1.96x
2+0.37x
3-0.03x
4+0.001x
5
Fig. 5 is work-hardening exponential n and the curve map apart from specimen surface thickness x, through the matching to discrete data point, obtains the distribution curve of work-hardening exponential n on Mo elastoplasticity gradient modified layer thickness direction and corresponding functional relation:
n＝-0.17+0.57x-0.22x
2+0.035x
3-0.003x
4+0.00008x
5
Can draw from result of implementation, adopt the inventive method quantitatively can try to achieve the mechanical property parameters of each point on the elastoplasticity gradient modified layer thickness direction of metal surface.
Claims (9)
1. a characterizing method for metal surface elastoplasticity gradient modified layer mechanical property, is characterized in that: adopt the characterization method that nanometer press-in test and finite element analogy combine.
2. the characterizing method of metal surface according to claim 1 elastoplasticity gradient modified layer mechanical property, it is characterized in that: the sample first for preparation carries out xsect to sticky edge sample, then according to the size of modified layer thickness and impression contact radius, its layering is characterized separately, the mechanical property parameters of each layer of last numerical fitting, thus the mechanical property parameters quantitatively obtaining each point on the elastoplasticity gradient modified layer thickness direction of metal surface.
3. the characterizing method of metal surface according to claim 1 elastoplasticity gradient modified layer mechanical property, is characterized in that: comprise the following steps:
(1) metal base pre-service: size elects Ф 18 mm × 5 mm as, carries out polishing to its surface;
(2) prepare elastoplasticity gradient modified layer: adopt plasma surface alloying method, reasonably select to infiltrate element, form high rigidity, wear-resistant and corrosion resistant elastoplasticity gradient modified layer in metallic substrate surface;
(3) to sticky edge sample: the xsect sample cut two first to sticking together, and then carries out edge sample, to the xsect sample inlayed, polishing is carried out;
(4) layering simplifies: according to the thickness of elastoplasticity gradient modified layer and the size of impression contact radius a, according to indent spacers △
lthe rule of>=2a, is divided into some sublayers by modified layer, thus makes elastoplasticity gradient modified layer be reduced to the form of elastoplasticity gradient layers;
(5) nanometer is utilized to be pressed into the Elastoplastic Performances in Simulation parameter of test in conjunction with each sublayer of finite element analogy quantitatively characterizing;
(6) the Elastoplastic Performances in Simulation parameter of Matlab 6.5 to each sublayer is utilized to carry out curve fitting, the mechanical property parameters of each point on the elastoplasticity gradient modified layer thickness direction of quantitative solving metal surface.
4. the characterizing method of metal surface according to claim 3 elastoplasticity gradient modified layer mechanical property, it is characterized in that: the concrete steps of described step (1) and (3) middle polishing are: first adopt SiC emery paper to polish, then the diamond polishing spray of 0.5 μm is adopted to carry out polishing, until surface roughness Ra < 0.1 μm; After polishing, for subsequent use after using pure water, acetone ultrasonic cleaning successively.
5. the characterizing method of metal surface according to claim 3 elastoplasticity gradient modified layer mechanical property, is characterized in that: infiltrate element in described step (2) and select according to the intermetallic mutual solubility of metal phase diagram.
6. the characterizing method of metal surface according to claim 3 elastoplasticity gradient modified layer mechanical property, it is characterized in that: in described step (2), the technological parameter of plasma surface alloying method is: die opening is set to 18 mm, operating air pressure is 40 Pa, source electrode negative bias is-660 ~-900 V, workpiece pole negative bias is-300 ~-650 V, technological temperature is 900 DEG C, and temperature retention time is 3 h.
7. the characterizing method of metal surface according to claim 3 elastoplasticity gradient modified layer mechanical property, is characterized in that: the thickness of each sublayer in described step (4)
hequal and satisfied:
h>=4a.
8. the characterizing method of metal surface according to claim 3 elastoplasticity gradient modified layer mechanical property, it is characterized in that: in described step (5), the concrete steps of nanometer press-in test are: nanometer press-in test selects the nanometer press fit instrument of band built-in scan probe microscope to carry out, the number of test points of each sublayer is no less than 5, and test load elects 8 mN as.
9. the characterizing method of metal surface according to claim 3 elastoplasticity gradient modified layer mechanical property, it is characterized in that: in described step (5), the concrete steps of finite element analogy are: utilize the load-displacement curves of ANSYS v10.0 finite element software to each sublayer test gained to carry out back analysis calculating, obtain the Elastoplastic Performances in Simulation parameter of each sublayer.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108414379A (en) * | 2018-03-16 | 2018-08-17 | 太原理工大学 | A method of indentation Test extraction metal elastic-plastic mechanical parameter in situ |
| CN108918308A (en) * | 2018-05-16 | 2018-11-30 | 太原理工大学 | A kind of quantitatively characterizing method of titanium alloy surface gradient modified layer Elastoplastic Performances in Simulation parameter |
| CN109870476A (en) * | 2019-03-27 | 2019-06-11 | 哈尔滨工业大学 | A kind of method that ceramic matric composite mechanical property quickly characterizes |
-
2015
- 2015-04-08 CN CN201510164286.1A patent/CN104792617A/en active Pending
Non-Patent Citations (2)
| Title |
|---|
| 田珂 等: "弹塑性梯度材料热机耦合分析的有限元方法", 《航空工程进展》 * |
| 马永: "金属表面渗镀复合改性层接触力学行为探讨", 《中国博士学位论文全文数据库 工程科技I辑》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108414379A (en) * | 2018-03-16 | 2018-08-17 | 太原理工大学 | A method of indentation Test extraction metal elastic-plastic mechanical parameter in situ |
| CN108414379B (en) * | 2018-03-16 | 2020-05-15 | 太原理工大学 | Method for extracting metal elastoplasticity parameters through in-situ press-in test |
| CN108918308A (en) * | 2018-05-16 | 2018-11-30 | 太原理工大学 | A kind of quantitatively characterizing method of titanium alloy surface gradient modified layer Elastoplastic Performances in Simulation parameter |
| CN109870476A (en) * | 2019-03-27 | 2019-06-11 | 哈尔滨工业大学 | A kind of method that ceramic matric composite mechanical property quickly characterizes |
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