GB/T 222-2006 English PDF (GBT222-2006)

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GB/T 222-2006: Permissible tolerances for chemical composition of steel products
GB/T 222-2006
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.080.20
H 40
Partially replacing GB/T 222-1984
Permissible Tolerances for Chemical
Composition of Steel Products
Issue date. February 5, 2006 Implementation date. August 1, 2006
Issued by. General Administration of Quality Supervision, Inspection
and Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3 
1. Scope ... 4 
2. Terms and Definitions ... 4 
3. Sampling and Sample-making Methods for Product Analysis ... 5 
4. Chemical Analysis Method ... 5 
5. Permissible Tolerance for Product Analysis ... 5 
Foreword
This Standard is formulated based on the relevant parts about permissible
variations for chemical composition in GB/T 222-1984 “Method of Sampling
Steel for Determination of Chemical Composition and Permissible Variations
for Product Analysis”.
This Standard replaces the relevant parts of “permissible tolerances for
chemical composition of steel products” in GB/T 222-1984; method of
sampling steel for determination of chemical composition of steel will be
specified in separate independent standard.
Compared the content of permissible tolerances of finished chemical
composition in this Standard and in GB/T 222-1984, the main changes are as
follows.
- Applicable scope of Table 1 is changed from common straight carbon
steel and low alloy steel to unalloyed steel and low alloy steel; applicable
scope of Table 2 is changed to alloy steel (see 6.1 in 1984 version, and
5.1 in this Standard).
- It is clarified that permissible tolerance values in Table 1 and Table 2 are
applicable to steel products of which the cross-sectional area is not larger
than 65000mm2 (5.1 in this Standard).
- It is supplemented that analysis on finished products replace heat
analysis (5.4 in this Standard).
- Permissible tolerance values of carbon and manganese elements in
Table 1 and Table 2 are adjusted; and provisions on elements, such as
aluminium, cobalt, nitrogen gas and calcium, are added.
This Standard was proposed by State Bureau of Metallurgical Industry.
This Standard shall be under the jurisdiction of National Technical Committee
of Standardization for Steel.
Drafting organization of this Standard. China Metallurgical Information and
Standardization Research Institute.
Main drafters of this Standard. Wu Qiansi, Luan Yan, Liu Baoshi and Dai
Qiang.
The first edition of this Standard was issued in August 1984.
Permissible Tolerances for Chemical Composition of
Steel Products
1. Scope
This Standard specifies the permissible tolerances of chemical composition of
finished unalloyed steel (excluding boiling steel), low alloy steel and alloy steel
products that are relative to the threshold value of melted chemical
composition; and it provides the relevant terms and definitions.
2. Terms and Definitions
This following terms and definitions are applicable to this Standard.
2.1 Heat (or cast/ladle) analysis
It refers to a procedure that adopts ingot sample during molten steel casting to
make test sample, and then carrying out chemical analysis. The analytic result
refers to average chemical composition of molten steel of the same batch.
2.2 Product analysis
Product analysis refers to take sample from processed finished steel product
(including steel feed), and then to analyze its chemical composition. Product
analysis is mainly used to check chemical composition, and it is also called
check analysis. Due to the fact that molten steel is distributed unevenly
(segregation) during crystallization, composition value of product analysis is
different from composition value of heat analysis sometimes.
2.3 Permissible tolerances for product analysis
It refers to that - although composition value of heat analysis is within the
exceed composition threshold value specified in standards, however, because
of segregation of steel composition, a permissible value of product analysis is
possible to exceed the threshold value that is specified by the standard. The
permissible value is the permissible tolerance for product analysis.
of threshold value of chemical composition as specified in the standard, or
shall not exceed the result of lower limit of threshold value of chemical
composition specified in the standards, subtracting lower deviation. In product
analysis of the same batch, one element is only allowed to have one time
deflected, and upper deviation and lower deviation shall not appear
simultaneously.
Example. For high-quality carbon structure #20 steel, limit carbon content of
smelting chemical composition specified in the standard is. upper limit 0.23%,
lower limit 0.17%; if carbon content is 0.25% when adding steel with the same
smelting number, it refers to that the value is 0.02% higher than the upper limit
specified in standards; if carbon content of steel with another smelting number is
0.15%, it refers to that the value is 0.02% lower than the lower limit specified in
standards; these two values of carbon content are deemed as qualified according
to provisions of Table 1.
5.4 If test sample for heat analysis is not available or reliable result of
smelting composition can not be obtained due to incorrect sample for heat
analysis, then product analysis can replace heat analysis, however, the
composition value of product analysis shall comply with provisions of smelting
composition, and permissible tolerances for product analysis specified in
Tables 1, 2 and 3 must NOT be adopted.
>0.50~2.00 0.02 0.02
>2.00~5.00 0.05 0.05
>5.00~10.00 0.10 0.10
>10.00~15.00 0.15 0.15
>15.00~22.00 0.20 0.20
>22.00~30.00 0.25 0.25
Nb + Ta
≤1.50 0.05 0.05
>1.50~5.00 0.10 0.10
>5.00 0.15 0.15
Ta ≤0.10 0.02 0.02
Cu
≤0.50 0.03 0.03
>0.50~1.00 0.05 0.05
>1.00~3.00 0.10 0.10
>3.00~5.00 0.15 0.15
>5.00~10.00 0.20 0.20
Al
≤0.15 0.01 0.005
>0.15~0.50 0.05 0.05
>0.05~2.00 0.10 0.10
>2.00~5.00 0.20 0.20
>5.00~10.00 0.35 0.35
≤0.02 0.005 0.005
>0.02~0.19 0.01 0.01
>0.19~0.25 0.02 0.02
>0.25~0.35 0.03 0.03
>0.35 0.04 0.04
≤1.00 0.03 0.03
>1.00~2.00 0.05 0.05
>2.00~5.00 0.07 0.07
>5.00~10.00 0.10 0.10
>10.00~20.00 0.15 0.15
≤0.50 0.03 0.03
>0.50~≤1.50 0.05 0.05
>1.50 0.07 0.07
Se All 0.03 0.03