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NDT test result accuracy improving method and apparatus thereof

A technology of test results and accuracy, applied in the direction of using one-time impact force to test material strength, investigation stage/state change, etc., can solve problems such as tissue coarsening range, misjudgment of steel performance, tissue growth of test piece, etc., to achieve The effect of reducing test data error and improving accuracy

Active Publication Date: 2013-09-25
NANJING IRON & STEEL CO LTD
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If the welding parameters are not properly controlled, the range of the welding heat-affected zone will be very large, resulting in coarsening of the structure in a large range and deteriorating NDT performance
In addition, if the cooling rate of the test piece is not controlled during surfacing welding, due to the influence of human factors and environmental factors, the size and cooling rate of the heat affected zone of the test piece will be different each time surfacing welding, and the obtained tissue type And the grain size is also different, so the measured NDT temperature is also different, resulting in unstable NDT test results
These factors will affect the accuracy of the test results, resulting in misjudgment of the performance of the steel
[0003] Patent No. CN101017124A discloses a method and device for measuring the non-plastic transition temperature. The device provided by this patent is the cooling device commonly used at present. The device uses an indirect cooling method to indirectly cool the specimen placed on the base plate by cooling the base plate. This cooling method has the following disadvantages: 1. The cooling efficiency of this cooling method is low, and it takes a long time to reach the expected cooling temperature; 2. Due to Most of the specimens are exposed to the ambient temperature and are easily affected by the ambient temperature; 3. The local high temperature diffuses quickly during welding, and this cooling method cannot suppress the increase in temperature, and the range of microstructure coarsening inevitably increases

Method used

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  • NDT test result accuracy improving method and apparatus thereof
  • NDT test result accuracy improving method and apparatus thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0027] A device to improve the accuracy of NDT test results, such as figure 1 and figure 2 As shown, it includes a cooling box 3 that can pass into the circulating cooling liquid and a specimen tank 4 placed inside the cooling box 3. On the surface of the same side of the cooling box 3, a cooling liquid outlet 2 and a cooling liquid outlet 2 for the cooling liquid to enter and exit are respectively provided. The height of the liquid inlet 1 and the cooling liquid outlet 2 is higher than that of the cooling liquid inlet 1, and the height of the cooling liquid outlet 2 is flush with the upper surface of the cooling box 3. The side wall and the bottom surface of the test piece groove 4 are provided with several A circular through-hole 6 that is evenly distributed to allow cooling liquid to flow through is provided with several (two in this embodiment) ribs 7 that protrude toward the inside of the tank body on the bottom surface of the test piece tank 4 .

[0028] In this embod...

Embodiment 2

[0035] The methods and devices used to improve the accuracy of NDT test results are as follows:

[0036] 1. Make the E690 marine engineering steel that needs to be measured into a test specimen 5.

[0037] 2. Connect the coolant inlet 1 and coolant outlet 2 of the cooling box 3 to circulating liquid nitrogen. After the liquid nitrogen can circulate and pass through the cooling box 3 stably, the test piece 5 is placed in the test piece groove 4, so that the test piece 5 Fully contact with liquid nitrogen, and weld the crack source weld bead required for the test on the test piece 3, and reduce the temperature of the test piece 5 during surfacing welding by liquid nitrogen.

[0038] 4. The crack source is processed on the weld bead of specimen 5, the cooling rate of the heat affected zone is 50~100°C / s, the structure of the heat affected zone is martensite + lath bainite, and the width of the heat affected zone is 0.5mm (Without using the cooling equipment, the cooling rate of ...

Embodiment 3

[0041] The methods and devices used to improve the accuracy of NDT test results are as follows:

[0042] 1. The 9% Ni low temperature steel to be measured is made into test specimen 5.

[0043]2. Connect the cooling liquid inlet 1 and the cooling liquid outlet 2 of the cooling box 3 to the circulating cooling water. After the cooling water can circulate and pass through the cooling box 3 stably, the test piece 5 is placed in the test piece groove 4, so that the test piece 5 Fully contact with the cooling water, and weld the crack source weld bead required for the test on the test piece 3, reduce the temperature of the test piece 5 during surfacing welding through the cooling water, and the cooling rate of the heat-affected zone is 30~60℃ / s, The structure of the heat-affected zone is martensite + bainite, and the width of the heat-affected zone is 0.6mm (without using the cooling equipment, the cooling rate of the heat-affected zone is 0~45°C / s, and the structure of the heat-af...

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Abstract

The invention relates to a metal material NDT test method and an apparatus thereof, and especially relates to an NDT test result accuracy improving method and an apparatus thereof. The method comprises the steps of making a test piece, surfacing-welding a crack source weld bead, processing the crack source, cooling the test piece and carrying out a hammer dropping test. In the above crack source weld bead surfacing welding step, all side surfaces and the bottom surface of the test piece on a test piece slot directly contact with a cooling liquid, and then the test piece is surfacing-welded with the crack source weld bead. The apparatus comprises the cooling liquid, a cooling box and the test piece slot, a cooling liquid outlet and a cooling liquid inlet which are used for the cooling liquid to enter and exit are respectively arranged on the cooling box, the cooling box has a non-closed structure, the sidewalls and / or the bottom surface of the body of the test piece slot are provided with through holes respectively, and the through holes are connected with the cooling box through the cooling liquid. The apparatus has the advantages of high cooling efficiency, strong stability, and minimization of the area influenced by the welding heating.

Description

technical field [0001] The invention relates to a method and a device for NDT testing of metal materials, in particular to a method and a device for improving the accuracy of NDT test results. Background technique [0002] According to the applicant's understanding, the toughness of ferritic structural steel decreases with the decrease of temperature. When the temperature drops to a certain value, it reaches a critical point. At this time, the fracture is completely crystalline and brittle. This temperature is called no plastic transition. The nil-ductility transition temperature (NDT) is the highest temperature that characterizes the brittle fracture of steel containing small cracks under dynamic loading yield stress; the non-plastic transition temperature of the material can be determined by the drop weight test method. Use the temperature to obtain the maximum crack size allowed to prevent brittle fracture under the design stress, or obtain the minimum stress for brittle ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/30G01N25/12
Inventor 邓伟崔强车马俊李恒坤吴年春尹雨群
Owner NANJING IRON & STEEL CO LTD
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