CN107966351B - Method for wrapping sample by using nickel net - Google Patents
Method for wrapping sample by using nickel net Download PDFInfo
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- CN107966351B CN107966351B CN201711156738.7A CN201711156738A CN107966351B CN 107966351 B CN107966351 B CN 107966351B CN 201711156738 A CN201711156738 A CN 201711156738A CN 107966351 B CN107966351 B CN 107966351B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
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- Investigating Or Analyzing Materials Using Thermal Means (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention provides a method for wrapping a sample by using a nickel net, which comprises the following steps: two nickel nets are symmetrically wrapped on the sample; putting the wrapped sample into a clamp matched with the shape of the sample; placing the clamp with the sample in a tablet press for stamping; after the punching is finished, taking out the sample in the clamp; and welding the thermocouple wires on the spot welding machine of the processed sample, wherein the welding point falls on the nickel net. According to the invention, as the weldability of nickel and nickel alloy is good, the nickel screen partially wraps the sample, the nickel screen and the surface of the sample are tightly pasted after cold pressing, and the thermocouple wire is welded on the nickel screen instead of the sample, so that the temperature measurement problem of the material with poor weldability is solved, the thermal simulation test can be accurately carried out, and the success rate of the test is improved. The invention has simple appliance, reduces the test cost and has simple and easy operation.
Description
Technical Field
The invention relates to the technical field of thermal simulation experiments, in particular to a method for wrapping a sample by using a nickel screen.
Background
The physical simulation technique for material processing is widely used in the field of material research and development and processing because it is effective and cost-effective. The accurate measurement of the temperature of the thermal simulation sample in the test process is the key of success or failure of the test, and the thermocouple wire is welded on the steel material sample by a spot welding machine under the normal condition, so that the welding spot is firm, and the temperature measurement is accurate; however, when the sample of the simulation test is made of aluminum, copper, magnesium or the like, since the resistivity is low, it is difficult to weld the thermocouple wire and the sample firmly, so that the test frequently fails and cannot be performed, and the application range of the thermal simulation test machine is restricted.
The problem of welding thermocouple wires on a material with poor weldability is solved to a certain extent by a Chinese patent invention with the publication number of CN105651618A, namely a method for arranging thermocouple wires on a sample, but in the method, welding points of two thermocouple wires are easy to be pulled apart in the deformation process of the sample, so that the temperature measurement fails, and the test success rate is not high.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides the method for wrapping the sample by using the nickel screen, which is simple to operate, greatly improves the success rate of the test, reduces the test cost and expands the application range of the thermal simulation testing machine.
The invention provides a method for wrapping a sample by using a nickel net, which comprises the following steps:
1) using two nickel nets to symmetrically wrap the sample;
2) putting the wrapped sample into a clamp matched with the shape of the sample;
3) placing the clamp with the sample in a tablet press for stamping;
4) after the punching is finished, taking out the sample in the clamp;
5) and welding the thermocouple wires on the spot welding machine of the processed sample, wherein the welding point falls on the nickel net.
Further, in the step 1), the sample is cylindrical, the two nickel nets symmetrically wrap the sample around the circumference of the sample, and each nickel net wraps the half circumference of the sample.
3. The method for wrapping a test specimen with a nickel mesh according to claim 2, wherein the nickel mesh is wrapped at an axially intermediate position of the test specimen.
Further, the width of the selected nickel screen is 1-2 mm, and the length of the selected nickel screen is larger than half of the outer circumference of the sample.
Furthermore, the selected nickel screen has the surface density of more than 280g per square meter, the number of holes of more than 100PPI and the thickness of more than 1.7 mm.
Further, in the step 2), the clamp is composed of two opposite clamp blocks with a semicircular opening in the middle, and the radius of the semicircular opening is matched with that of the sample.
Further, the clamp splice is the cuboid, and its length is 4 times of sample radius, and the width is 2 times of sample radius, highly is 2 times of sample radius, semicircle form trompil is located on the big face of clamp splice.
In the step 3), a fixed pressure is used for stamping, and the fixed pressure is less than 80% of the yield strength Rp0.2 of the sample material.
Further, in the step 5), the thermocouple wire is a K-type thermocouple, and the voltage of the welding thermocouple is 20-40V.
Further, the test piece is a cylindrical axial compression test piece or a rod-shaped tensile test piece.
According to the invention, as the weldability of nickel and nickel alloy (K-type thermocouple) is good, the nickel screen partially wraps the sample, the nickel screen and the surface of the sample are tightly pasted after cold pressing, and the thermocouple wire is welded on the nickel screen instead of being welded on the sample, so that the temperature measurement problem of a material with poor weldability is solved, a thermal simulation test can be accurately carried out, and the success rate of the test is improved. The invention has simple appliance, reduces the test cost and has simple and easy operation.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
FIG. 1 is a schematic side view of a wrapped sample according to an embodiment of the present invention;
FIG. 2 is a schematic front view of a wrapped-treated test specimen according to an embodiment of the present invention;
FIG. 3 is a front view of a clamp of an embodiment of the present invention;
FIG. 4 is a top view of a clamp of an embodiment of the present invention;
FIG. 5 is a graph of stress-strain curves comparing wrapped and unwrapped welded aluminum specimens according to an embodiment of the present invention;
FIG. 6 is a graph comparing the stress-strain curves of wrapped and unwrapped welded steel coupons for an example of the present invention;
fig. 7 is a flowchart of a method for wrapping a sample using a nickel mesh according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
The embodiment of the invention provides a method for wrapping a sample by using a nickel net, which comprises the following steps of:
and step S1, symmetrically wrapping the sample by using two nickel nets. As shown in fig. 1 and 2, the sample 1 is cylindrical, and the two nickel nets 2 symmetrically wrap the sample 1 around the circumference of the sample 1, and each nickel net 2 wraps half of the circumference of the sample 1. Preferably, the nickel screen 2 is wrapped at the axial middle position of the test sample 1, the width of the selected nickel screen 2 is 1-2 mm, the length of the selected nickel screen is more than half of the outer perimeter of the test sample 1, the surface density of the selected nickel screen 2 is more than 280 g/square meter, the number of holes is more than 100PPI, and the thickness of the selected nickel screen is more than 1.7 mm. The sample 1 is a cylindrical axial compression sample or a rod-shaped tensile sample.
And step S2, putting the wrapped sample into a clamp matched with the shape of the sample. As shown in fig. 3 and 4, the clamp consists of two opposing clamp blocks with a semicircular opening in the middle, the radius of the semicircular opening matching the radius of the sample. Preferably, the clamp splice is the cuboid, and its length is 4 times of sample radius, and the width is 2 times of sample radius, highly is 2 times of sample radius, semicircle form trompil is located on the big face of clamp splice.
And step S3, placing the clamp with the sample in a tablet press for stamping. Wherein, a fixed pressure is used during stamping, and the fixed pressure is less than 80% of the yield strength Rp0.2 of the material of the sample.
In step S4, after the press is completed, the sample in the jig is taken out.
And step S5, welding the thermocouple wires on the spot welding machine of the processed sample, and enabling the welding points to fall on the nickel screen. The thermocouple wire is a K-type thermocouple, and the voltage of the welding thermocouple is 20-40V.
According to the invention, as the weldability of nickel and nickel alloy (K-type thermocouple) is good, the nickel screen partially wraps the sample, the nickel screen and the surface of the sample are tightly pasted after cold pressing, and the thermocouple wire is welded on the nickel screen instead of being welded on the sample, so that the temperature measurement problem of a material with poor weldability is solved, a thermal simulation test can be accurately carried out, and the success rate of the test is improved. The invention has simple appliance, reduces the test cost and has simple and easy operation.
In a first specific embodiment of the invention, 7075 aluminum alloy with the components shown in table 1 is processed into a cylindrical sample with phi 10 × 15mm, the yield strength Rp0.2 of the alloy at normal temperature is measured on a universal testing machine to be 455Mpa, two nickel nets with the specification of 2mm in width and 25mm in length are wrapped around the circumference of the sample respectively at the middle part of the sample, the wrapped nickel nets are placed in a clamp, the size of the clamp is 20mm × 10mm × 10mm, the half-circle radius of the cut is 5mm, the nickel nets are placed on a tablet press, the pressure of the tablet press is 10Mpa, after the pressing is completed, the sample is taken out from the clamp, the sample is placed under a spot welding machine to be subjected to thermocouple wire welding, the welding voltage is 30V, the welding is checked to confirm that the welding is firm, a high-temperature compression experiment is carried out on a Gleeble-1500D thermal simulation testing machine, the sample is vacuumized to be less than 10Pa, the sample is heated to 450 ℃ at 2 ℃/s, the sample is heated for 60 seconds, the sample is deformed at a true strain rate of 0.9, the strain rate of 0.a smooth welding point is completed, a strain curve is shown in a strain curve, the temperature control experiment, the sample is not subjected to be loosened according to a temperature stress curve, and the thermocouple wire welding process is directly shown in a temperature control curve, the temperature control experiment, the temperature of a thermocouple wire.
TABLE 17075 chemical composition of aluminum alloys
In a second embodiment of the invention, a medium manganese steel with the components as shown in table 2 is processed into a cylindrical sample with phi 8 × 15mm, firstly, the yield strength Rp0.2 of the alloy at normal temperature is 674Mpa, two nickel nets with the specification of 2mm wide and 20mm long are respectively wrapped around the circumference of the sample at the middle part of the sample on a universal testing machine, the wrapped nickel nets are placed in a clamp with the size of 16mm × 8mm × 8mm and the semicircular radius of 4mm, the nickel nets are placed on a tablet press, the pressure of the tablet press is 10Mpa, after the pressing is completed, the sample is taken out of the clamp, the thermocouple wire welding is carried out under a spot welder, the welding voltage is 40V, the welding is checked to confirm that the welding is firm, a high-temperature compression experiment is carried out on a Gleeble-1500D thermal simulation testing machine, firstly, the sample is vacuumized to be less than 10Pa, the sample is heated to 900 ℃ at 10 ℃/s, the sample is insulated for 300 seconds, the true strain rate of 1/s is deformed, the strain 0.4 is completed, the stress curve is smoothly tested as shown in fig. 6 c, the sample is directly wrapped in a thermocouple wire temperature measurement process, the temperature stress curve can be directly shown in a graph, and the critical point can be directly shown in the graph, the test point.
TABLE 2 chemical composition of manganese steels
TABLE 3 Key Point data comparison Table
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (9)
1. A method for wrapping a sample by using a nickel net is characterized by comprising the following steps:
1) using two nickel nets to symmetrically wrap a sample, wherein the sample is cylindrical, wrapping the sample by the two nickel nets symmetrically around the circumferential direction of the sample, and wrapping the half circumference of the sample by each nickel net;
2) putting the wrapped sample into a clamp matched with the shape of the sample;
3) placing the clamp with the sample clamped in a tablet press for stamping to enable the nickel screen to be adhered to the surface of the sample;
4) after the punching is finished, taking out the sample in the clamp;
5) and welding the thermocouple wires on the spot welding machine of the processed sample, wherein the welding point falls on the nickel net.
2. The method for wrapping a test specimen with a nickel mesh according to claim 1, wherein the nickel mesh is wrapped at an axially intermediate position of the test specimen.
3. The method for wrapping a test specimen with a nickel screen according to claim 1, wherein the nickel screen is selected to have a width of 1 to 2mm and a length greater than half of the outer circumference of the test specimen.
4. The method of claim 1 wherein the nickel screen is selected to have an areal density of greater than 280 grams per square meter, a pore count of greater than 100PPI and a thickness of greater than 1.7 mm.
5. The method for wrapping the test specimen by using the nickel mesh as claimed in claim 1, wherein in the step 2), the clamp is composed of two opposite clamp blocks with a semicircular opening in the middle, and the radius of the semicircular opening is matched with that of the test specimen.
6. The method for wrapping a sample with a nickel screen according to claim 5, wherein the clamping block is a rectangular parallelepiped having a length of 4 times the radius of the sample, a width of 2 times the radius of the sample, and a height of 2 times the radius of the sample, and the semicircular openings are located on the large surface of the clamping block.
7. The method for wrapping the test sample by using the nickel mesh as claimed in claim 1, wherein in the step 3), a fixed pressure is used for stamping, and the fixed pressure is less than 80% of the yield strength Rp0.2 of the material of the test sample.
8. The method for wrapping the sample by using the nickel mesh as claimed in claim 1, wherein in the step 5), the thermocouple wire is a K-type thermocouple, and the welding voltage of the thermocouple wire is 20-40V.
9. The method for wrapping a test specimen with a nickel mesh according to any one of claims 1 to 8, wherein the test specimen is a cylindrical axial compression test specimen or a rod-shaped tensile test specimen.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711156738.7A CN107966351B (en) | 2017-11-20 | 2017-11-20 | Method for wrapping sample by using nickel net |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711156738.7A CN107966351B (en) | 2017-11-20 | 2017-11-20 | Method for wrapping sample by using nickel net |
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| CN107966351A CN107966351A (en) | 2018-04-27 |
| CN107966351B true CN107966351B (en) | 2020-07-14 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5770081A (en) * | 1980-10-20 | 1982-04-30 | Hitachi Ltd | Brazing method |
| CN202720067U (en) * | 2012-06-06 | 2013-02-06 | 沈阳飞机工业（集团）有限公司 | Thermocouple for pipe braze welding |
| CN104014897A (en) * | 2014-06-11 | 2014-09-03 | 沈阳飞机工业（集团）有限公司 | Metal conduit welding technology control method |
| CN104155166A (en) * | 2014-08-29 | 2014-11-19 | 山西太钢不锈钢股份有限公司 | Preparation and determination method of sample for compression of metal material with high thermal conductivity |
| CN105651618A (en) * | 2016-03-01 | 2016-06-08 | 内蒙古科技大学 | Method for disposing thermocouple wires on test specimen |
-
2017
- 2017-11-20 CN CN201711156738.7A patent/CN107966351B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5770081A (en) * | 1980-10-20 | 1982-04-30 | Hitachi Ltd | Brazing method |
| CN202720067U (en) * | 2012-06-06 | 2013-02-06 | 沈阳飞机工业（集团）有限公司 | Thermocouple for pipe braze welding |
| CN104014897A (en) * | 2014-06-11 | 2014-09-03 | 沈阳飞机工业（集团）有限公司 | Metal conduit welding technology control method |
| CN104155166A (en) * | 2014-08-29 | 2014-11-19 | 山西太钢不锈钢股份有限公司 | Preparation and determination method of sample for compression of metal material with high thermal conductivity |
| CN105651618A (en) * | 2016-03-01 | 2016-06-08 | 内蒙古科技大学 | Method for disposing thermocouple wires on test specimen |
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| CN107966351A (en) | 2018-04-27 |
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