This standard is applicable to the determination of transverse rupture strength of cemented carbide. This standard is applicable to cemented carbide with very low plasticity. GB/T 3851-1983 Method for determination of transverse rupture strength of cemented carbide GB/T3851-1983 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of transverse rupture strength of cemented carbideHardmetals-determination of transverse rupture strengthThis standard applies to the determination of transverse rupture strength of cemented carbide. UdC 621.762.1
GB 3851--83
ISO 3327 ---1982
This standard is used for cemented carbide with very low plasticity. If it is used for cemented carbide with significant plastic deformation before fracture, inaccurate results may be obtained. In this case, this method can only be used for comparison. This standard is equivalent to ISO3327-1982 "Determination of transverse rupture strength of cemented carbide". 1 Explanation of symbols
Table 1 Explanation of symbols
Force required for fracture test
Distance between two supporting points
Width perpendicular to the specimen height
Height of specimen parallel to the applied forceCorrection factor for compensating chamfer
Transverse fracture strength
The specimen is placed freely and horizontally on two supporting points and fractured under a short-term static force applied at the midpoint of the span. 3
Preparation and requirements of specimens
The specimens shall have a rectangular cross section and the dimensions shall be as specified in Table 2. 3.1
Table 2 Dimensions of specimens
35 ± 1
6.5±0.25
5.25±0.25
Note: · In general, if the surface conditions of the two types of specimens are the same, the strength of the type B specimen is about 10% higher than that of the type A specimen. The two types of specimens have similar reproducibility.
3.2 The four long faces of the sample are ground with a diamond grinding wheel (preferably resin bonded) under sufficient coolant. The grinding amount each time shall not exceed 0.01mm, and all wear marks shall be parallel to the length direction. The grinding thickness of each surface shall not be less than 0.1mm, and the surface roughness Ra<0.4μm. The four long edges shall be ground with chamfers of 0.15~0.2mm, and all wear marks shall also be parallel to the length direction. Issued by the National Bureau of Standards on September 14, 1983
Implemented on September 1, 1984
GB3851-83
Sintered specimens can also be used. In order to avoid burrs, such specimens should be chamfered by 0.4-0.5mm before sintering, and the chamfer should be 453.3 The parallelism deviation of each two opposite faces of the four long faces is: for sintered specimens, the deviation is not more than 0.05mm for every 10mm: for layered specimens, the deviation is not more than 0.01mm for every 10mm. 3.4 The measurement of width and height used for calculation results should be carried out in the middle of the specimen, with an accuracy of 0.01mm. 3.5 The specimen shall not have obvious surface cracks and structural defects. 4 Equipment
4.1 The test equipment shall have a device that can apply a uniform force increase, and its accuracy shall be 1% or better. 4.2 The test fixture shall have two freely horizontal supporting round bars (rollers) with a certain distance between the two round bars and a horizontal force-applying round bar (roller). The diameter of the round bars is the same, and the value can be between 3.2 and 6 mm, or a round ball with a diameter of 10 mm can be used for force-applying.
The supporting round bars and force-applying round bars (balls) must be made of tungsten carbide hard alloy, which does not produce sub-plastic deformation due to force, and its surface roughness Ra is not more than 0.63μm.
4.3 The supporting round bars shall be fixed in parallel, and the span for type A specimens shall be 30±0.5mm; for type B specimens, it shall be 14.5±0.5mm. When measuring the span, it shall be accurate to 0.1mm for type B specimens and to 0.2mm for type A specimens. 4.4 The fixed round bars shall be so that the parallelism deviation is reduced to a minimum. 4.5 For safe lifting, the fixture shall be equipped with a suitable protective cover. 5 Test steps
Place the specimen flatly on the supporting rod so that the length of the specimen is aligned with the axial direction of the supporting rod. For type B specimens, place the wide surface on the supporting rod.
5.2 Slowly bring the force-applying rod (or ball) into contact with the specimen. The deviation between the line (or point) of action of the force-applying rod and the midpoint of the specimen span shall not exceed 0.5 mm for type A specimens and 0.2 mm for type B specimens.
5.3 Stress the specimen at a uniform rate not exceeding 200 N/mm per second. Note: For type B specimens, the force applied is equivalent to the maximum speed of 1600 N per second; for type A specimens, it is equivalent to the force applied in situ at a speed of 600 N per second.
6 Result expressionbZxz.net
The transverse rupture strength Rt (N/mm2) is calculated by the following formula: 6.1
R =3×k×F×1
2×b×h2
The k value is as specified in Table 3.
Table 3 Chamfer correction coefficient k value
Specimen type
edge, mm
Note: The above formula for calculating the transverse rupture strength does not take into account the influence of possible plastic deformation. 190
Joint coefficient
GB3851—83
The result shall be reported as the arithmetic mean of at least five transverse rupture strength measurements, and its value shall be rounded to 10N/mm2Test report
The test report shall include the following contents:
This standard number:
Details required to identify the specimen;
Specimen type and surface preparation method; Force application method,
Measured results, a footnote shall be added to the lower right of the transverse rupture strength symbol: For type A specimen: 30
For type B specimen: 15
For example: Rtr30
All operating conditions not specified in this standard or selected by oneself; Any conditions that have affected the results. Additional remarks:
This standard was proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by Zhuzhou Cemented Carbide Factory. The main drafters of this standard are Wang Xueqin, Ma Songhua and Shen Bin. From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB851-75 "Test Method for Bending Strength of Cemented Carbide" shall be invalid.
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