DL/T 1845-2018Test method for Leeb hardness of high-alloy steels in power equipment (English PDF)

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This standard is under the jurisdiction of the Technical Committee for Standardization of Metal Materials for Power Stations in the Power Industry.

1 Scope

This standard specifies the test principles, test objects, symbol descriptions and tests for the Leeb hardness test of high-alloy steel products or components of power equipment Instrument, test piece requirements, test procedures, test result processing, conversion relationship between Leeb hardness and Brinell hardness, etc.

This standard applies to the determination of the Leeb hardness of the following products or parts of high alloy materials and the conversion relationship between the Leeb hardness and the Brinell hardness.

a) 10Cr9Mo1VNbN (ASTM A/ASME SA335-P91, ASTM A/ASME SA213-T91), 10Cr9MoW2VNbBN (ASTM A/ASME SA335-P92, ASTM A/ASME SA213-T92);

b) GH4145, C422 (22Cr12NiWMoV);

c) 20Cr13, 05Cr17Ni4Cu4Nb, 14Cr12Ni3Mo2VN, 22Cr12NiWMoV;

This standard applies to the determination of the Leeb hardness of D-type impact devices.

2 Normative references

The following documents are essential for the application of this document. For dated references, only the dated versions apply to this article Pieces. For the cited documents without date, the latest version (including all amendments) applies to this document.

GB/T 17394.1 Metallic materials Leeb hardness test Part 1: Test method GB/T 17394.2 Metallic materials Leeb hardness test Part 2: Inspection and calibration of hardness tester

3 Test principle

The test principle of the Leeb hardness should meet the relevant requirements of GB/T 17394.1.

4 Symbols and instructions

The Leeb hardness value is followed by the symbol "HL" followed by a suffix character indicating the type of impact body. All data used in this standard Obtained from the Leeb hardness test of the D-type impact device, the data unit is HLD.

Other hardness converted with the Leeb hardness tester shall be attached with the corresponding hardness symbol before the Leeb hardness symbol.

Examples.

570HLD means that the Leeb hardness value measured using the impact body of type D in the direction of gravity is 570.

200HBHLD means that the Brinell hardness value converted from the Leeb hardness value measured by the D-type impact device is.200.

5 Test equipment

6 Sample

7 Test procedures

7.1 The daily inspection of the hardness tester used shall be carried out in accordance with the relevant provisions of GB/T 17394.1.The material and hardness of the test piece should be selected A standard hardness block with a similar range calibrates the hardness tester.

7.2 The instrument should be kept clean and tidy during the test, and the impact body should be cleaned regularly to remove iron dust and dust contaminated on the impact body Sundries. The ball head of the impact body shall be periodically inspected and calibrated in accordance with the provisions of GB/T 17394.2.If it does not meet the requirements, it shall be replaced immediately.

Note 1.During the impact body test of the Leeb hardness tester, it is easy to be contaminated with debris such as iron filings or dust.

If it is not accurate.

Note 2.Long-term high-frequency use of the Leeb hardness chronograph may cause wear on the impact body ball head. Using a worn impact body ball head for the Leeb hardness test will produce 生Error.

7.3 Before testing, check the contamination or looseness of the support ring regularly, and keep it in a tightened state. The sediment and dust on the bottom of the support ring need to be Clear. After the rubber coating of the support ring wears out, a new support ring needs to be replaced. When the support ring is replaced, accessories that are fully compatible with the hardness tester should be used.

7.4 The ambient temperature during the test shall comply with the relevant regulations of GB/T 17394.1.

7.5 The Leeb hardness tester should be avoided in the occasion of strong vibration, severe dust, corrosive gas, magnetic field or electromagnetic field.

7.6 During the test, the direction of the impact velocity vector should be perpendicular to the local surface area to be tested, and the test piece and the impact device should be closely connected Touch, can not produce relative sliding.

7.7 The hardness tester should be set correctly before the test. During the test, first push down the loading sleeve to lock the impact body, and hold the coil component with one hand Press the supporting ring of the impact device on the surface of the test piece, press or push the release device with the other hand to measure the hardness, and pass the indicating device Read the corresponding hardness value set. If the deviation from the gravity direction exceeds 5°, it will cause measurement error and should be corrected.

Note 3.When testing the Leeb hardness of the test piece on site, a variety of test directions may appear. For the hardness tester with automatic direction correction function, it should be set correctly.

For hardness testers without automatic direction correction function, it is advisable to use a suitable clamping device to fix the standard hardness block, calibrate the Leeb hardness tester, and then repair Positive Leeb hardness value.

7.8 The distance between the center of the two indentations and the edge of the test piece should allow the entire support ring to be installed on the test piece.

The distance of the edge of the test piece should not be less than 5mm.

Figure 1 Schematic diagram of indentation position control

Table 1 Typical indentation diameters of different hardness materials

7.10 To determine the Leeb hardness, at least 5 points should be measured at each measurement site and recorded.

7.11 During the same measurement process of the same part, if the difference between the hardness values exceeds 20HLD, use a standard hardness test block to calibrate the instrument If the number of measurements is increased again, if it still does not meet the requirements, record it truthfully.

7.12 Pipes with wall thickness less than 7mm shall not adopt this standard for on-site Leeb hardness measurement.

7.13 When conducting the Leeb hardness test on site, the surface of the tested part should comply with the provisions of Chapters 6 and 7.If grinding is required, the grinding depth should be 0.5mm ~ 1.0mm, and the minimum calculated wall thickness of the test piece should be guaranteed.

Note 4.The test is carried out in accordance with the details given in 7.13.If there are still other conditions that affect the accuracy of the Leeb hardness data, it is necessary to carry out for hardness testing, it is advisable to use the change trend of the Leeb hardness value obtained multiple times under the same conditions as the measurement basis.

8 Processing of test results

8.1 To determine the Leeb hardness, at least 5 points should be measured at each measurement site, removing a maximum value and a minimum value; use at least three the arithmetic mean of the effective test points is used as a Leeb hardness test data.

8.2 When the Leeb hardness is converted to the Brinell hardness, it shall be converted according to the material in accordance with Appendix A of this standard. High alloy not in Appendix A Materials can be converted according to the method in Appendix B.

8.3 During the test, when the reading of the Leeb hardness tester exceeds the standard Leeb hardness block ±12HLD, a special test block can be used for correction.

The hardness comparison test block clamping device and comparison test block assembly are shown in Appendix C, and the correction method is shown in Appendix D.

8.4 If the hardness deviates from the specified value of the corresponding standard (see Appendix E), the inspection range should be expanded near the abnormal hardness point to check out Areas with abnormal hardness. At the same time, a portable Brinell hardness tester should be used for measurement and verification. Arithmetic average of Brinell hardness at the same location the value should be within the specified range of the corresponding standard, but one of the points is allowed to exceed the specified range by 5 HB.

9 Test records and reports

9.1 The test record shall include at least the following.

a) Implement the number of this standard, namely DL/T xxxx-201x;

b) Hardness tester name, model, number, type of impact device;

c) Test material grade, component name, component specification and surface condition, etc.;

d) Test result and single basic reading value;

e) Coupling method, test position, impact direction relative to the direction of gravity, etc.;

f) Test temperature;

g) Test date.

9.2 The test report shall include at least the following.

a) Implement the number of this standard, namely DL/T xxxx-201x;

b) Name, model and number of hardness tester;

c) Test material grade, component name, component specification and surface condition, etc.;

d) Test results;

e) Test date.

Appendix A

(Normative appendix) Conversion table of Leeb hardness of D-type impact device of high alloy material Appendix B (Informative appendix) Test method for conversion of Leeb hardness and Brinell hardness when testing high alloy materials other than Appendix A, when the Leeb hardness value needs to be accurately converted to the Brinell hardness value, a comparative test should be done to obtain Corresponding conversion relationship.

The comparative test is such a method. use the certified Leeb hardness tester and the Brinell hardness tester to test on the same test piece respectively, in the three or more Brinell hardness indentations that need to be converted are measured evenly around the seven-point Leeb hardness, removing a maximum value and removing a maximum value.

Low value, using the average value of the Leeb hardness and the corresponding average value of the Brinell hardness as the corresponding values, to make a hardness comparison curve, the comparison curve is at least Ten sets of corresponding data should be included, and another test piece should be taken to verify the results.

Appendix C

(Informative appendix) Leeb hardness comparison test block clamping device and comparison test block assembly

Figure C.1 Schematic diagram of the clamping device of the Leeb hardness comparison test block and the comparison test block assembly

Appendix D

(Informative appendix) Leeb hardness correction method During the test or after the measurement, when the reading of the Leeb hardness tester exceeds the standard Leeb hardness block ±12HLD, the instrument cannot be replaced.

During measurement, the Leeb hardness test value can be corrected. The correction is calculated according to formula (D.1).

Appendix E

(Informative appendix) Hardness values of high alloy materials commonly used in power equipment