GB/T 9790-2021Metallic materials - Vickers and Knoop microhardness tests of metallic and other inorganic coatings (English PDF)

Foreword

This Standard was drafted in accordance with the rules in GB/T 1.1-2020 Directives

for Standardization - Part 1: Rules for the Structure and Drafting of Standardizing

Documents.

This Standard serves as a replacement of GB/T 9790-1988 Metallic and Related

Coatings - Vickers and Knoop Microhardness Tests. In comparison with GB/T 9790-

1988, apart from structural adjustments and editorial modifications, the main technical

changes are as follows:

---The test forces in the Scope are modified; the stipulations of the measurement

of surface microhardness of coatings are added (see Chapter 1; Chapter 1 of

Version 1988);

---Terms and Definitions are added (see Chapter 3);

---The expression of principles is modified (see Chapter 4; Chapter 3 of Version

1988);

---Examples of result expression of hardness value and contents of multiple

symbols are added (see Chapter 5);

---The stipulations of the measurement compliance of hardness tester are added

(see 6.1);

---The Vickers indenter and Knoop indenter parameters are modified (see 6.2.1.1

and 6.2.1.2; 5.2.1.1 and 5.2.1.2 of Version 1988);

---The stipulations of hardness reference blocks are modified (see 6.3; 5.3 of

Version 1988);

---The expression form of test force selection range is modified from text to a table;

an annotation to the guideline of test force selection for materials with hardness

value less than 100 is added (see 7.1; 6.1 of Version 1988);

---The description of vibration influencing factors is modified (see 7.4; 6.4 of

Version 1988);

---The description of roughness influencing factors is modified (see 7.5.1; 6.5.1 of

Version 1988);

---The stipulations of surface inclination of specimen are modified (see 7.6.2; 6.6.2

of Version 1988);

---The description of microscope resolution influencing factors is modified (see 7.8;

1 Scope

This Standard specifies the principles, symbols and descriptions, equipment,

influencing factors of measurement accuracy, test procedures, uncertainty of results

and test reports of Vickers and Knoop microhardness tests of metallic and other

inorganic coatings.

This Standard is applicable to the determination of multiple coatings, such as:

electrodeposited coatings, autocatalytic coatings, sprayed aluminum coatings and

aluminum anodized coatings, etc. During the determination, the test force is generally

not greater than 9.807 N (1 kgf). 8.3 of this Standard is applicable to the determination

of microhardness of coating cross-sections. 8.4 of this Standard is applicable to the

determination of microhardness of coating surface.

NOTE 1: Part 1 ~ Part 4 of GB/T 18449 describes the test of Knoop hardness of metallic

materials. Part 1 ~ Part 4 of GB/T 4340 describes the test of Vickers hardness of

metallic materials. GB/T 21838 (all parts) describes instrumented indentation test

for metallic material hardness and material parameters.

NOTE 2: the test force of coatings is usually selected from the test force within the range

of Vickers microhardness in GB/T 4340.1-2009. However, since the test force

shall be as large as possible, the test force within the small force value of Vickers

hardness range of GB/T 4340.1-2009 may also be selected.

2 Normative References

The contents of the following documents constitute the indispensable clauses of this

document through normative references in the text. In terms of references with a

specified date, only versions corresponding to the date are applicable to this document.

In terms of references without a specified date, the latest version (including all the

modifications) is applicable to this document.

GB/T 4340.1-2009 Metallic Materials - Vickers Hardness Test - Part 1: Test Method

(ISO 6507-1:2005, MOD)

GB/T 4340.2 Metallic Materials - Vickers Hardness Test - Part 2: Verification and

Calibration of Testing Machines (GB/T 4340.2-2012, ISO 6507-2:2005, MOD)

GB/T 4340.4 Metallic Materials - Vickers Hardness Test - Part 4: Tables of Hardness

Values (GB/T 4340.4-2009, ISO 6507-4:2005, IDT)

GB/T 6462 Metallic and Oxide Coatings - Measurement of Coating Thickness -

Microscopical Method (GB/T 6462-2005, ISO 1463:2003, IDT)

GB/T 18449.1-2009 Metallic Materials - Knoop Hardness Test - Part 1: Test Method

(ISO 4545-1:2005, MOD)

GB/T 18449.2 Metallic Materials - Knoop Hardness Test - Part 2: Verification and

Calibration of Testing Machines (GB/T 18449.2-2012, ISO 4545-2:2005, MOD)

GB/T 18449.4 Metallic Materials - Knoop Hardness Test - Part 4: Tables of Hardness

Values (GB/T 18449.4-2009, ISO 4545-4:2005, IDT)

JJG 151 Verification Regulation of Metallic Vickers Hardness Testers

JJG 1047 Metallic Knoop Hardness Testers

3 Terms and Definitions

There are no terms and definitions that need to be defined in this document.

4 Principle

With the specified test force, slowly and vertically press a diamond indenter with a

certain shape, at an appropriate press-in velocity, into the measured coating; after

maintaining it for a specified time, remove the test force; use a microscope to measure

the diagonal length of the indentation. Substitute the measured diagonal length into

the hardness calculation formula, or in accordance with the diagonal length, check the

table of hardness values (check GB/T 4340.4 for Vickers hardness; check GB/T

5 Symbols and Descriptions

Vickers and Knoop microhardness are respectively represented by HV and HK. The

figure before the symbol indicates hardness value, and the symbol is followed by:

a) Test force (Newton multiplied by the proportional coefficient 0.102) (see Table

1);

b) Test force retention time, expressed in seconds. Generally speaking, the test

force is maintained for 10 s ~ 15 s. If the test force retention time is not within

the range of 10 s ~ 15 s, indicate the test force retention time.

The representation method of Vickers hardness is shown in Example 1. The

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