GB/T 37598-2019 English PDF (GBT37598-2019)

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GB/T 37598-2019: Inspection of non-metallic inclusions in steel -- Blue fracture test method
GB/T 37598-2019
Inspection of non-metallic inclusions in steel--Blue fracture test method
ICS 77.040.99
H24
National Standards of People's Republic of China
Inspection of non-metallic inclusions in steel
Blue break method
Published on.2019-06-04
2020-05-01 implementation
State market supervision and administration
China National Standardization Administration issued
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard was proposed by the China Iron and Steel Association.
This standard is under the jurisdiction of the National Steel Standardization Technical Committee (SAC/TC183).
This standard was drafted. Northeast Special Steel Group Co., Ltd., Metallurgical Industry Information Standards Institute.
The main drafters of this standard. Kang Ge, Cheng Lijie, Yan Yuming, Liu Yanjun, Wen Zhengmao, Cheng Yu.
Inspection of non-metallic inclusions in steel
Blue break method
1 Scope
This standard stipulates the use of blue breakage method to test macroscopic non-metallic inclusions in steel, including preparation, test methods and test results of samples.
Inspection report and other content.
This standard is applicable to the inspection of macroscopic non-metallic inclusions with a length of not less than 1 mm and a width of not less than 0.1 mm.
2 Normative references
The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article.
Pieces. For undated references, the latest edition (including all amendments) applies to this document.
GB/T 8170 Numerical Rounding Rules and Representation and Determination of Limit Values
GB/T 30067 Metallographic terminology
3 Terms and definitions
The following terms and definitions defined in GB/T 30067 apply to this document.
3.1
Macroscopic non-metallic inclusion macronon-metalicinclusion
Strip-shaped non-metallic inclusions visible visually or with a magnification of no more than 10 times, usually gray, light yellow or yellowish green
colour.
3.2
Blue treatment bluing
A heat treatment method in which steel is heated to an appropriate temperature to produce a very thin blue oxide film on its surface.
4 Principle
At the blue brittle temperature, the fractured metal matrix forms a blue oxide film, while the non-metallic inclusions do not oxidize, maintaining the original color.
It is often in the form of a non-crystalline strip such as gray, light yellow or yellowish green. Observe the longitudinal fracture by visual inspection or by means of an amplifying device not more than 10 times
See the size, number and distribution of strip-shaped non-metallic inclusions.
5 Preparation of samples
5.1 Sampling method
The steel is cut into transverse specimens and can be cut by hot saw, cold saw, flame cutting, shearing, etc. The thickness of the test piece is 15mm~20mm.
The schematic diagram of the fracture sampling is shown in Figure 1. The deformation and heat affected zone caused by sampling should be guaranteed to be outside the fracture. On the centerline of the cross section of the specimen,
The V-groove is engraved by the shaft, and the depth of the groove is such that the remaining sample thickness is not less than 10 mm.
Description.
1---grooving;
2---rolling direction;
3---Slice.
Figure 1 Schematic diagram of fracture sampling
5.2 Number of samples
The number of samples and sampling locations shall be specified in the product standard or determined by the supplier and the buyer. When not specified, two steels can be extracted
Branch sample.
5.3 Sample preparation
5.3.1 When preparing the fracture, place the sample groove face down on the support table of the fracture machine (or pressure tester) to ensure the impact knife edge and break.
The center line of the groove of the mouth sample is matched, and then the fracture sample is broken once under the impact load (or pressure), and repeated punching is strictly prohibited. for
Ensure that the fracture is flush and the sample can be pre-heat treated.
5.3.2 To display non-metallic inclusions, the sample is blued in one of the following ways.
a) The sample is heated in the furnace to a blue brittle temperature (300 ° C ~ 350 ° C), and the quick break is taken out so that the sample is at a blue brittle temperature at the time of the fracture.
b) Heat the fractured sample to a blue brittle temperature (300 ° C ~ 350 ° C), making the fracture blue.
Note. High alloy steel can increase the blue brittle temperature properly, but should not exceed 530 °C.
6 Test methods
6.1 On a fracture surface of the dual fracture (usually selecting the severe surface of the defect), visually or using an amplification device with a magnification of not more than 10 times
Observe the size, quantity or distribution of non-metallic inclusions.
6.2 Divide the fracture surface into three zones. surface zone, intermediate zone and central zone, respectively denoted by S, M and C, and the fracture face area is divided as shown in Figure 2.
Description.
1 --- notch;
2 --- fracture;
3 --- rolling direction;
S---surface area;
M---middle zone;
C---Central area.
Figure 2. Fracture surface area division
6.3 Determine the fracture area and measure the length of each inclusion and the number of inclusions in each area. Ferritic strip, carbide strip, segregation line
Or loose lines, easy to be confused with non-metallic inclusions, should pay attention to distinguish.
7 test results
7.1 Record the length of each inclusion in different areas of each sample. Calculate the sum of the lengths of the inclusions on the inspection area, ie the total length;
The ratio of length to inspection area is the average length. Number of inclusions less than 1.0 mm in length and less than 0.1 mm in width recorded in the original record
Quantity, does not participate in the calculation of the ratio of the total length to the inspection area. The original inspection result record can be referred to Appendix A.
7.2 Record the length, quantity or maximum non-metallic inclusion length of each sample according to the requirements of the product standard.
7.3 The test and test results shall comply with the provisions of GB/T 8170, and the values shall be revised to approximately 0.1 mm.
8 Inspection report
The inspection report should include the following items.
a) the standard number;
b) steel number, furnace number, specification and sample number;
c) inspection results;
d) Inspection report number, date and inspector.
Appendix A
(informative appendix)
Blue break initial test result record
The table of the original test results of the blue break is shown in Table A.1.
Table A.1 Blue test results of original test results
Sample code
Inspection area
Dm2
Inclusion size/mm
SMC
The maximum length
Mm
Total number of articles
Total length
Mm
Average length
Mm/dm2
9102-
T/