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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 5242-2006 Check rules and test methods of cemented carbide products.
The following main changes have been made with respect to GB/T 5242-2006 (the previous edition):
-Normative references are enriched with new ones;
-The inspection items are updated, with the items like cobalt magnetization, chemical composition, thermal diffusivity, elastic modulus and drop test (or hammering test) added and the item cross-section microstructure deleted;
-Clause 3 “Terms and definitions” is deleted;
-The 4.1.2 “Inspection classification” and 4.4 “Judgment of inspection result” are deleted;
-Clause 5 “Acceptance” is deleted;
-Annex A (normative) is added.
This standard was proposed by China Nonferrous Metals Industry Association.
This standard is under the jurisdiction of SAC/TC 243 National Technical Committee on Nonferrous Metals of Standardization Administration of China.
The previous editions of the standard replaced by this standard are as follows:
——GB/T 5242-1985 and GB/T 5242-2006.
Inspection rules and test methods of cemented carbide products
1 Scope
This standard specifies the inspection items, batching rules, sampling rules and test methods for the inspection of cemented carbide products.
This standard is applicable to the inspection and test for chemical composition, physical and mechanical properties, microstructure, geometric dimension and appearance quality of sintered cemented carbide products.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the normative document (including any amendments) applies.
GB/T 1817 Test method for impact toughness of cemented carbides at room temperature
GB/T 3488 (all Parts) Hardmetals - Metallographic determination of microstructure
GB/T 3489 Hardmetals - Metallographic determination of porosity and uncombined carbon
GB/T 3848 Hardmetals - Determination of (the magnetization) coercivity
GB/T 3849 (all Parts) Hardmetals - Rockwell hardness test (scale A)
GB/T 3850 Impermeable sintered metal materials and hardmetals - Determination of density
GB/T 3851 Hardmetals - Determination of transverse rupture strength
GB/T 4324.25 Methods for chemical analysis of tungsten - Part 25: Determination of oxygen content - Pulse heating inert gas fusion-infrared absorption method
GB/T 5124 (all Parts) Methods for chemical analysis of hardmetals
GB/T 5166 Sintered metal materials and hardmetals - Determination of Young's modulus
GB/T 7997 Hardmetals - Vickers hardness test
GB/T 11108 Test method for thermal diffusivity of hardmetal
GB/T 20255 (all Parts) Methods for chemical analysis of hardmetals
GB/T 23369 Standard test method for determination of magnetic saturation (MS) of cemented carbides
GB/T 26050 Hardmetals - Determination of contents of metallic elements by X-ray fluorescence - Fusion method
3 Inspection rules
3.1 Inspection items
3.1.1 Chemical composition
The inspection items of chemical composition include main metal content, total carbon and oxygen content.
3.1.2 Physical and mechanical properties
The inspection items of physical and mechanical properties mainly include density, Rockwell hardness (or Vickers hardness) and transverse rupture strength (bending strength), and where necessary, such items as coercivity (magnetization), cobalt magnetization (or magnetic saturation), cutting property, drilling property, impact toughness, thermal diffusivity, elastic modulus and drop test (or hammering test) may also be inspected.
3.1.3 Metallographic structure
The inspection items of metallographic structure mainly include porosity, uncombined carbon and microstructure of the alloy.
3.1.4 Dimension
The dimension inspection items include geometric dimension and its tolerance, positional tolerance and geometric tolerance.
3.1.5 Appearance quality
The appearance quality inspection mainly checks whether the surface of the product is subjected to delamination, cracking, poor compacting, peeling, bubbling, bending, edge defect, arris defect, burr, sticking, trace, pitting, hole plugging, pollution, oxidation, carburization, decarbonization, undersintering, overburning and other defects.
3.2 Batching rules
Cemented carbide products shall be submitted for inspection in batches, and the specific batching rules shall be consistent with the requirements of relevant standards for cemented carbide products.
3.3 Sampling rules and test methods
Each batch of cemented carbide products shall be sampled and tested in accordance with those specified in Table 1.
Table 1 Sampling rules and test methods of cemented carbide products
No. Inspection item Sampling rules Test method
1 Chemical composition Randomly take one sample from each batch of products for inspection GB/T 4324.25, GB/T 5124, GB/T 20255 and GB/T 26050
2 Density Randomly take at least two samples from each batch of products GB/T 3850
3 Rockwell hardness (or Vickers hardness) Randomly take at least two samples from each batch of products GB/T 3849 (or GB/T 7997)
4 Transverse rupture strength (bending strength) Prepare at least five specimens for each batch of products GB/T 3851
5 Coercivity (magnetization) Randomly take at least two samples from each batch of products GB/T 3848
6 Cobalt magnetization (or magnetic saturation) Randomly take at least two samples from each batch of products GB/T 23369
7 Cutting property Randomly take at least two samples from each batch of products Determined by the Supplier and the Purchaser through negotiation
8 Drilling property Randomly take at least three samples from each batch of products Determined by the Supplier and the Purchaser through negotiation
9 Impact toughness Prepare at least five specimens for each batch of products GB/T 1817
10 Thermal diffusivity Prepare at least three specimens for each batch of products GB/T 11108
11 Elastic modulus Prepare at least three specimens for each batch of products GB/T 5166
12 Drop test (or hammering test) For each batch of products, bar products with a length of no less than 150mm shall be subjected to drop or hammering test one by one, among which, those with a diameter of no less than 2mm shall be subjected to drop test, and those with a diameter less than 2mm shall be subjected to hammering test. Annex A
13 Metallographic structure Randomly take at least two samples from each batch of products GB/T 3489 and GB/T 3488
14 Dimension It shall meet the requirements of corresponding standards for cemented carbide products Inspect by using measuring tools with appropriate precision
15 Appearance quality It shall meet the requirements of corresponding standards for cemented carbide products By visual inspection. Where necessary, it shall be amplified for inspection
Note 1: For the purpose of analysis and testing, the chemical composition may be tested by using the mixture in the same batch.
Note 2: For large products with a unit weight greater than 300g, appropriately sized standard test pieces which are sintered in the same furnace may be prepared for the inspection on physical and mechanical properties and metallographic structure.
Foreword i
1 Scope
2 Normative references
3 Inspection rules
Annex A (Normative) Test methods for drop test (or hammering test) of bar products
