Detail of GB/T 230.1-2018

Introduction of GB/T 230.1-2018

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. GB/T 230 consists of the following three parts under the general title of Metallic materials - Rockwell hardness test: ——Part 1: Test method; ——Part 2: Verification and calibration of testing machines; ——Part 3: Calibration of reference blocks. This part is Part 1 of GB/T 230. This part is developed in accordance with the rules given in GB/T 1.1-2009. This part replaces GB/T 230.1-2009 Metallic materials - Rockwell hardness test - Part 1: Test method. The following main technical changes have been made with respect to GB/T 230.1-2009: ——The materials of standard type of Rockwell ball indenter are modified (see Clause 1; Clause 1 of Edition 2009); ——The serviceable range of the steel indenter balls is modified (see Clause 1; Clause 1 of Edition 2009); ——The applicable range of Rockwell hardness HRA and HRB is modified (see Table 1; Table 1 of Edition 2009); ——The rules for applicable range of Rockwell hardness HRC extending to 10HRC are modified (see note in Table 1; note in Table 1 of Edition 2009); ——The durations of the preliminary force F0 and the additional test force F1 are modified (see 7.6 and 7.9; 7.3 and 7.5 of Edition 2009); ——The distance between the centers of two adjacent indentations is modified (see 7.13; 7.8 of Edition 2009); ——The rounding requirements for Rockwell hardness value are deleted [see d), Clause 9 of Edition 2009]; ——The requirements of specimen roughness are modified (see 6.1 of Edition 2009); ——The indenter used in the thin products HR30TSm and HR15TSm in Annex A is modified (see Note 1 of Annex A; A.1 in Annex A of Edition 2009); ——Annex C is changed as normative annex, and the contents of the daily verification procedures in Annex C are modified (see Annex C; Annex E of Edition 2009); ——Annex D is changed as normative annex (see Annex D; Annex F of Edition 2009); ——The evaluation method related to uncertainty of measured hardness values in Annex G is modified (see Annex G; Annex G of Edition 2009). This part is modified in relation to international standard ISO 6508-1:2016 Metallic Materials - Rockwell Hardness Test - Part 1: Test Method”. The structure of this part is basically consistent with ISO 6508-1:2016. Technical differences between this part and ISO 6508-1:2016 are marked with perpendicular single line (|) in the outside page margin of the provisions concerned. Compared with ISO 6508-1:2016, technical differences and their reasons are as follows: ——The adjustment in "Normative references" of this part has technical differences to meet the technical specification in China; the adjustment situations are embodied in a concentrated way in Clause 2 "Normative references" and the specific adjustments are as follows: ● ISO 6508-2 is replaced by GB/T 230.2 which is modified in relation to the international standard; ● ISO 6508-3 is replaced by GB/T 230.3 which is modified in relation to the international standard; ● JJG 112 is added for reference (see Clause 5). ● JJG 1059.1 is added for reference (see Clause 8). The following editorial changes are also made in this part: ——Figure G.1 and corresponding notes are added in Annex G; ——The order of Annex C, Annex D, Annex E, and Annex F is adjusted according to the appearing order in the standard; ——Annex H and Annex I of the international standard are deleted. This part was proposed by China Iron and Steel Association. This part is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183). The previous editions of this part are as follows: ——GB/T 230-1983, GB/T 230-1991, GB/T 230.1-2004 and GB/T 230.1-2009; ——GB/T 1818-1979, GB/T 1818-1994. Metallic materials - Rockwell hardness test - Part 1: Test method 1 Scope This part of GB/T 230 specifies the method for Rockwell regular and Rockwell superficial hardness tests for metallic materials with scales of A, B, C, D, E, F, G, H, K, 15N, 30N, 45N, 15T, 30T, and 45T. It is applicable to stationary and portable hardness testing machines. For specific materials or products, other specific standards apply (for instance, GB/T 3849.1[1], GB/T 9097[2]). Note: Attention is drawn to the fact that the use of tungsten carbide composite for ball indenters is considered to be the standard type of Rockwell indenter ball. Steel indenter balls are allowed to continue to be used only when complying with Annex A. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 230.2-2012 Metallic materials - Rockwell hardness test - Part 2: Verification and calibration of testing machines (Scales A, B, C, D, E, F, G, H, K, N, T) (GB/T 230.2-2012, ISO 6508-2: 2005, MOD) GB/T 230.3 Metallic materials - Rockwell hardness test - Part 3: Calibration of reference blocks (Scales A, B, C, D, E, F, G, H, K, N, T) (GB/T 230.3-2012, ISO 6508-3: 2005, MOD) JJG 112 Metallic Rockwell hardness testers (scales A, B, C, D, E, F, G, H, K, N, T) JJF 1059.1 Evaluation and expression of uncertainty in measurement 3 Principle An indenter of specified size, shape, and material is forced into the surface of a test specimen under two force levels using the specific conditions defined in Clause 7. The specified preliminary force is applied and the initial indentation depth is measured, followed by the application and removal of a specified additional force, returning to the preliminary force. The final indentation depth is then measured and the Rockwell hardness value is derived from the difference, h, in the final and initial indentation depths and the two constants N and S (see Figure 1, Table 1, and Table 2) as shown in Formula (1): Rockwell hardness= (1) 4 Symbols, abbreviated terms and designations 4.1 The symbols, abbreviations terms and designations used in this part are shown in Figure 1, Table 1, Table 2 and Table 3. Indenters with diameters of 6.350mm and 12.70mm are also available, as permitted by product standards or agreement. See the indenter used in other scales in ASTM E18 [10]. Note 1: For some materials, the applicable range may be narrower than that shown in the table. Note 2: The previous unit of test force is kgf. For example, the total test force of 30kgf is converted to 294.2N. Key X——time Y——indenter position 1——indentation depth by preliminary force, F0 2——indentation depth by additional test force, F1 3——elastic recovery just after removal of additional test force, F1 4——permanent indentation depth, h 5——surface of specimen 6——reference plane for measurement 7——position of indenter 8——curve of indentation depth relative to time Figure 1 Principle diagram of Rockwell hardness test   Table 1 Rockwell Regular hardness scales Rockwell regular hardness scale Hardness symbol unit Type of indenter Preliminary force F0 Total force F Scaling constant S Full range constant N Applicable range of application (Rockwell regular hardness scales) A B C D E F G H K HRA HRBW HRC HRD HREW HRFW HRGW HRHW HRKW Diamond cone Ball 1.587 5mm Diamond cone Diamond cone Ball 3.175mm Ball 1.587 5mm Ball 1.587 5mm Ball 3.175mm Ball 3.175mm 98.07 N 98.07 N 98.07 N 98.07 N 98.07 N 98.07 N 98.07 N 98.07 N 98.07 NP 588.4 N 980.7 N 1.471 kN 980.7 N 980.7 N 588.4 N 1.471 kN 588.4 N 1.471 kN 0.002mm 0.002mm 0.002mm 0.002mm 0.002mm 0.002mm 0.002mm 0.002mm 0.002mm 100 130 100 100 130 130 130 130 130 20 HRA~95 HRA 10 HRBW~100 HRBW 20 HRCa~70 HRC 40 HRD~77 HRD 70 HREW~100 HREW 60 HRFW~100 HRFW 30 HRGW~94 HRGW 80 HRHW~100 HRHW 40 HRKW~100 HRKW a The applicable range of the test can be extended to 10 HRC if the surfaces of the diamond cone and spherical tip are polished along the axis of diamond cone and at least 0.4mm away from the tip. Table 2 Rockwell Superficial scales Rockwell superficial hardness scale Hardness symbol unit Type of indenter Preliminary force F0 Total force F Scaling constant S Full range constant N Applicable range of application (Rockwell superficial hardness scales) 15N 30N 45N 15T 30T 45T HR15N HR30N HR45N HR15TW HR30TW HR45TW Diamond cone Diamond cone Diamond cone Ball 1.587 5mm Ball 1.587 5mm Ball 1.587 5mm 29.42N 29.42N 29.42N 29.42N 29.42N 29.42N 147.1N 294.2N 441.3N 147.1N 294.2N 441.3N 0.001mm 0.001mm 0.001mm 0.001mm 0.001mm 0.001mm 100 100 100 100 100 100 70 HR15N~94 HR15N 42 HR30N~86 HR30N 20 HR45N~77 HR45N 67 HR15TW~93 HR15TW 29 HR30TW~82 HR30TW 10 HR45TW~72 HR45TW   Table 3 Symbols and abbreviated terms Symbol/Abbreviated term Definition Unit F0 Preliminary test force N F1 Additional test force (total force minus preliminary force) N F Total test force N S Scaling constant, specific to the scale mm N Full range constant, specific to the scale — h Permanent depth of indentation under preliminary test force after removal of additional test force (permanent indentation depth) mm HRA HRC HRD Rockwell regular hardness = HRBW HREW HRFW HRGW HRHW HRKW Rockwell regular hardness = HRN HRTW Rockwell superficial hardness= 4.2 The following is an example of the designation of Rockwell hardness. Example: Note 1: Previous versions of GB/T230 allowed the use of steel indenter balls, which required the suffix S. Note 2: The HR30TSm and HR15TSm scales are defined in Annex A, a capital S and a lower-case m are used indicating the use of steel indenter balls and a diamond spot specimen holder.

Contents of GB/T 230.1-2018

Foreword i 1 Scope 2 Normative references 3 Principle 4 Symbols, abbreviated terms and designations 5 Testing machine 6 Test piece 8 Uncertainty of the results 9 Test report 10 Conversions to other hardness scales or tensile strength values Annex A (Normative) Special HR30TSm and HR15TSm test for thin products Annex B (Normative) Minimum thickness of the test piece in relation to the Rockwell hardness Annex C (Normative) Daily verification procedure Annex D (Normative) Inspection of diamond indenters Annex E (Normative) Corrections to be added to Rockwell hardness values obtained on convex cylindrical surfaces Annex F (Normative) Corrections to be added to Rockwell hardness C scale values obtained on convex spherical test surfaces Annex G (Informative) Uncertainty of the measured hardness values Bibliography