GB/T 11354-2005 PDF in English
GB/T 11354-2005 (GB/T11354-2005, GBT 11354-2005, GBT11354-2005)
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GB/T 11354-2005 | English | 165 |
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Determination of nitrided case depth and metallographic microstructure examination for steel and iron parts
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GB/T 11354-1989 | English | 599 |
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Steel-iron parts--Determination of nitrided case depth and metallographic examination of nitriding structure
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Standards related to (historical): GB/T 11354-2005
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GB/T 11354-2005: PDF in English (GBT 11354-2005) GB/T 11354-2005
GB
NATIONAL STANDARD OF
THE PEOPLE’S REPUBLIC OF CHINA
ICS 25.200
J 36
Replacing GB/T 11354-1989
Determination of nitrided case depth and
metallographic microstructure examination for steel
and iron parts
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 Examination of prior metallographic structure ... 6
5 Specimen conditions ... 8
6 Determination method for nitrided case depth ... 9
7 Examination of brittleness of nitrided case ... 12
8 Examination of porosity of nitrided case ... 14
9 Examination of nitrides in nitrided case ... 16
10 Examination report ... 18
Annex A (Informative) Recommended etchant ... 19
Annex B (Informative) Partial test data ... 20
Foreword
This Standard is an amendment to GB/T 11354-1989 Steel-iron parts -
Determination of nitrided case depth and metallographic examination of
nitriding structure. The main content of this Standard consists of the following
parts..
- examination of original structure before nitriding (5 levels);
- determination of nitrided case depth (Hardness Method and
Metallographic Method);
- examination of brittleness of nitriding case (5 levels);
- examination of porosity of nitriding case (5 levels);
- examination of nervation and wave like nitride in nitriding diffusion case
(5 levels).
According to requirements of GB/T 1.1-2000 Directives for standardization-Part
1. Rules for the structure and drafting of standards, this Standard made
corresponding modifications in structure, layout format, text description. For
example.
- added Table of Contents, Foreword;
- simplified the home page format and adjusted the format of the other
content;
- modified “Subject content and scope of application” to “Scope”,
“References” to “Normative references”;
- added English names of relevant terms in “Terms and definitions”;
- added title of the first level of entry to each clause;
- added Annex B to provide performance data tables related to the standard
level.
This Standard replaces GB/T 11354-1989 Steel-iron parts - Determination of
nitrided case depth and metallographic examination of nitriding structure.
Annex A, Annex B of this Standard are informative.
This Standard was proposed by China Machinery Industry Federation.
This Standard shall be under the jurisdiction of National Technical Committee
on Heat Treatment of Standardization Administration of China.
Determination of nitrided case depth and
metallographic microstructure examination for steel
and iron parts
1 Scope
This Standard specifies determination method of nitrided case depth,
examination method and technical requirements for metallographic
microstructure before and after nitriding.
This Standard is applicable to the determination and evaluation on nitrided case
depth, brittleness, porosity and nervation and wave like nitride on the surface
of steel and iron parts which are treated by gas nitriding, ion nitriding,
nitrocarburizing treatment.
2 Normative references
The following standards contain the provisions which, through reference in this
Standard, constitute the provisions of this Standard. For dated references,
subsequent amendments (excluding corrections) or revisions do not apply to
this Standard. However, the parties who enter into agreement based on this
Standard are encouraged to investigate whether the latest versions of these
documents are applicable. For undated reference documents, the latest
versions apply to this Standard.
GB/T 7232 Terminology of metal heat treatment
GB/T 9450 Steels - Determination and verification of the depth of
carburized and hardened cases (ISO 2639.2002, MOD)
GB/T 9451 Determination of total or effective thickness of thin surface
hardened layers of steel parts (ISO 4970.1979, MOD)
3 Terms and definitions
For the purposes of this Standard, terms in GB/T 7232 and the following terms
and definitions apply.
3.1 prior metallographic structure (original structure)
overheated; the edges are not allowed to have chamfering and flaking.
5.3 Specimen requirements for examination of brittleness of nitrided
case
The roughness of specimen surface for examination of brittleness of nitrided
case is required to be. Ra ≤ 0.25 µm ~ 0.63 µm. The compound layer is not
allowed to be worn away.
6 Determination method for nitrided case depth
6.1 Hardness method
This Standard Vickers hardness. The test force is specified to be 2.94 N (0.3
kgf). The vertical distance measured from the surface of the specimen to a
height of 50 HV higher than the Vickers hardness of the substrate is the depth
of the nitrided case.
The hardness value (at least take the average of 3 points) measured at 3 times
the depth of the nitrided surface from the surface is taken as the measured
matrix hardness value.
For steel parts of which nitrided case hardness change is very smooth (such as
carbon steel or low carbon low alloy steel parts), the nitrided case depth shall
be measured from specimen surface along with vertical direction to the height
of 30 HV higher than the Vickers hardness of the substrate.
When the nitrided case depth does not suit indentation size, it shall use test
force within 1.96 N (0.2 kgf) ~ 19.6 N (2 kgf) based on agreement between
parties. An indication shall be made after HV. for example, HV0.2 which means
a test force of 1.96 N (0.2 kgf) is used.
The nitrided case depth is denoted by the Latin alphabet DN, in millimeters,
taking the two decimal places, for example, 0.25 DN (300HV0.5) means that
when boundary hardness is 300HV, the test force is 4.903 N (0.5 kgf), the
nitrided case depth shall be 0.25 mm.
6.2 Measurement steps and results
The measurement steps and results shall comply with requirements of GB/T
9450 and GB/T 9451.
6.3 Metallographic method
Under magnification of 100 or 200 times the microscope, measure the depth as
shown in Figure 2 ~ Figure 6. The distance measured from specimen surface
along with vertical direction to the height which has clear boundary with matrix
Figure 6 20 Steel nitrocarburizing 300°C tempering 1h (4% nitric acid
ethanol solution corrosion) ×200
7 Examination of brittleness of nitrided case
7.1 Grating of brittleness of nitrided case
The brittleness level of nitriding case, according to the degree of embrittlement
of Vickers hardness indentation angle, is divided into 5 levels, as shown in
Figure 7 and Table 2.
7.2 Examination method
The examination of brittleness of nitrided case shall use Vickers hardness tester.
The test force is determined as 98.07 N (10 kgf). The loading must be slow
(within 5 s ~ 9 s). Remain for 5 s ~ 10 s after loading is completed then remove
the load. In case of special circumstances, the test force of 49.03 N (5 kgf) or
294.21 N (30 kgf) may also be used based on agreement by the parties
concerned. But it must be converted according to values in Table 3.
7.3 Examination requirements
The Vickers hardness indentation shall be examined at a magnification of 100
times (see Figure 7 for rating level). It shall at least examine 3 points for each
workpiece. When more than 2 points are at same level, the rating shall be
carried out, otherwise it shall repeat the examination.
7.4 Requirements for brittleness of nitrided case of nitriding pieces
The brittleness of the nitriding case shall be examined at the working site of the
part or the surface of the furnace specimen. Qualification assessment. 1~3
levels for general parts, 1~2 levels for important parts. For parts with grinding
left after nitriding, it shall also be examined on the surface after machining
Nitrided case depth
e) Level 5
Figure 9 Nitrides in nitrided case level chart (4% nitric acid ethanol
solution corrosion) ×500
Figure 9 Description of nitrides level
Level Description of nitrides level Figure No.
1 A very small amount of nervation and wave like nitrides in the diffusion layer 9a)
2 A small amount of nervation and wave like nitrides in the diffusion layer 9b)
3 Many nervation and wave like nitrides in the diffusion layer 9c)
4 Severe nervation and wave like nitrides and a small amount of mesh distributed nitrides in the diffusion layer 9d)
5 Continuous mesh distributed nitrides in the diffusion layer 9e)
10 Examination report
The examination report shall contain the following information.
a) part reference number, part name, material and nitriding process;
b) part inspection position or specimen and reference number as well as
amount for examination;
c) examination method;
d) examination results;
e) date of examination and signature of inspector.
1050°C × 20 min oil quenching, 670°C
× 2 h nitriding treatment after
tempering. (500 ~ 505)°C ×...
...... Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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