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GB/T 9450-2005 English PDF (GBT9450-2005)

GB/T 9450-2005 English PDF (GBT9450-2005)

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GB/T 9450-2005: Steels -- Determination and verification of the depth of carburized and hardened cases

This standard specifies the meaning and determination of steel-parts carburizing and carbonitriding hardened-case depth. This standard is applicable to carburizing and carbonitriding hardened layer; and the parts that, when they are final-heat-treated, have a hardness of less than 450 HV at a distance of three times the case-hardened depth, from the surface. For steel-parts that can not meet the above conditions, it shall be determined in accordance with a special agreement. For steel-parts of which, at a distance of three times the hardened-case depth from the surface, the hardness is greater than 450 HV, this standard is still valid, provided that a limiting hardness value that is greater than 550 HV (in steps of 25HV) is selected for the case-hardened depth.
GB/T 9450-2005
ICS 25.200
J 36
GB
National Standard
of the PEOPLE Republic of China
Replacing GB/T 9450-1988
Steels - Determination and verification
of the depth of carburized and hardened cases
(ISO 2639.2002, MOD)
ISSUED ON. JULY 21, 2005
IMPLEMENTED ON. JANUARY 1, 2006
Issued by. General Administration of Quality Supervision, Inspection and Quarantine;
Standardization Administration Committee.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 5
4 General ... 6
5 Determination of hardened-case depth ... 6
6 Verification of hardened-case depth ... 8
7 Test report ... 10
Foreword
This standard modifies and adopts ISO 2639.2002 "Steels - Determination and verification of the depth of carburized and hardened cases" (English version). This standard is re-drafted and based on ISO 2639. 2002. Compared with ISO 2639. 2002, the technical differences are.
- Under certain conditions, and after negotiating and agreeing with the parties concerned, it may use furnace-sample to replace the actual part testing.
- Test force range of Vickers hardness is 0.9807 N (0.1 kgf) - 9.807 N (1 kgf). This replaces the 0.98 N (0.1 kgf) - 9.8 N (1 kgf) in previous standard. According to the requirements of GB/T 1.1-2000 "Standardization guide. Part 1. The structure and preparation of standard rules", the structure, writing format, and written expression of this standard have be modified and changed
correspondingly. For example.
For ISO 2639.2002, this standard quotes the Chinese national standards
to replace the corresponding international standards (see Chapter 2 of
this standard).
For ease of use, this standard makes the following editorial changes.
a) "This international standard" is changed to "this standard";
b) Use decimal point ?€?.?€? to replace the comma "," which acts as decimal point;
c) Remove the Foreword of ISO 2639.2002.
This standard replaces GB/T 9450-1988 "Steels - Determination and
verification of the depth of carburized and hardened cases".
The standard was proposed by the Machinery Industry Federation.
This standard shall be under the jurisdiction of the National Heat Treatment Standardization Committee.
Drafting organization of this standard. Beijing Electromechanical Institute. The main drafters of this standard. Shao Zhoujun, Li Hualin, Ma Lan, Li Qiao, and Hu Xiaoli.
This previous standard replaced by this standard is. GB/T 9450-1988.
Steels - Determination and verification
of the depth of carburized and hardened cases
1??Scope
This standard specifies the meaning and determination of steel-parts
carburizing and carbonitriding hardened-case depth.
This standard is applicable to carburizing and carbonitriding hardened layer; and the parts that, when they are final-heat-treated, have a hardness of less than 450 HV at a distance of three times the case-hardened depth, from the surface.
For steel-parts that can not meet the above conditions, it shall be determined in accordance with a special agreement.
For steel-parts of which, at a distance of three times the hardened-case depth from the surface, the hardness is greater than 450 HV, this standard is still valid, provided that a limiting hardness value that is greater than 550 HV (in steps of 25HV) ?€? is selected for the case-hardened depth.
2??Normative??references
The provisions in following documents become the provisions of this standard through reference in this standard. For dated references, the subsequent amendments (excluding corrigendum) or revisions do not apply to this
Standard, however, parties who reach an agreement based on this standard are encouraged to study if the latest versions of these documents are
applicable. For undated references, the latest edition of the referenced document applies.
GB/T 4340.1 Metallic materials. Vickers hardness test. Part 1. Test method GB/T 18449.1 Metallic materials. Knoop hardness test. Part 1. Test method 3??Terms??and??definitions
The following terms and definitions apply to this standard.
case-hardened depth (of a carburized and hardened case)
hardness on a cross-section that is perpendicular to the part surface. That is, the hardness value acts as the ordinate; the distance to the surface acts as the abscissa; draw a hardness distribution curve. Then use graphic method to obtain from the curve.
5.3 Test method
5.3.1 Specimen
Unless otherwise specially agreed, it shall measure on the cross section of a part that is final-heat-treated. Under certain conditions, it may use the furnace-samples.
5.3.2 Preparation of the test surface
In order to accurately measure the diagonal length of hardness impression, the test surface shall be grinded and polished. During the grinding and polishing process, it should take all measures to prevent the specimen surface from chamfered or overheating.
5.3.3 Hardness measurement
The width (W) is within the range of 1.5 mm. measure Vickers hardness on 1 or multiple parallel lines that are perpendicular to the specimen surface (see Figure 1).
The distance (S) between the centers of every 2 adjacent impressions shall not be less than 2.5 times the impression diagonal line (see Figure 1). The distance difference (a2 - a1) BETWEEN successive adjacent impression
centers AND specimen surface shall not exceed 0.1m. The precision of
distance measuring BETWEEN impression centers AND specimen surface
shall be within the range of ??0.25 ??m. And the measurement precision of each hardness impression diagonal line shall be within the range of ??0.5 ??m. Unless otherwise specially agreed by the parties, under appropriate conditions, it shall use HV0.1 (0.9807 N) - HV1 (9.807 N) test force to obtain Vickers (or Knoop) impression hardness. And use optical instrument (camera system) to measure the impression under above-400X magnification.
Measurement shall be conducted at the position agreed by the parties. It shall be performed on 2 or more hardened-lines on the specimen surface that is well prepared. And draw out a hardness distribution curve for each line.
Note. when using interpolation method, it is better to check the hardness at the area immediately below the surface. If there is excessive residual austenite on sub-surface, The hardness at this area may be lower than the limiting hardness of 550 HV. Figure 3 Mathematical verification of hardened-case depth
7??Test??report
The test report shall contain the following information.
a) Test parts?€? name, materials and the heat treatment process;
b) Parts?€? test locations and quantity;
c) Measurement results of hardened-case depth;
d) Anomalies and contingencies found during the test.

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