ASTM B886-2019 pdf free download

ASTM B886-2019 pdf free download.Standard Test Method for Determination of Magnetic Saturation (Ms) of Cemented Carbides
1. Scope
1.1 This test method covers the determination of magnetic saturation (Ms) of cemented carbide powder materials and sintered products using magnetic saturation induction test instrumentation. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Summary of Test Method
4.1 For Permanent Magnet Instrument—A test specimen is statically positioned with the long axis perpendicular to the magnetic field generated by a permanent magnet and sensing coils of the test apparatus. The specimen is magnetized to induction saturation by the field and translated linearly that the intrinsic magnetic moment of the specimen’s binder phase induces a dc current to flow in the sensing coils of the test apparatus. The induced current is proportional to the amount of magnetic binder phase present in the test specimen. Measure- ment of the induced current permits calculation of the intrinsic magnetic saturation of the test sample. 4.2 For Electromagnet Instrument—A test specimen is placed into a holder housing the Hall probe and sensing coils which has been positioned between the poles of the electro- magnet. The magnetic field is increased while the sensing coils measure the magnetic flux of the specimen. The magnetic flux can be related to the intrinsic magnetic saturation of the test specimen.
5. Significance and Use
5.1 This test method allows the nondestructive measure- ment of the magnetic fraction of the binder phase in cemented carbide powder materials and sintered product, and may be used as an indirect measure of the carbon level in the material or product. 5.2 Measurement of magnetic saturation provides a com- parison of the relative fraction of magnetic binder phase, that is, cobalt, nickel, or iron, present in the material and can be used for acceptance of product to specification. 5.3 Measurement of magnetic saturation can be used as a measure of the quality of powder material.
6. Interferences
6.1 No direct absolute measurement of magnetic saturation can be made. The measurement is a relative comparison of standard reference materials. 6.2 Measurement of magnetic saturation is a nondestructive “bulk” measurement which is averaged over the test specimen volume. The technique cannot be used to infer anything regarding the relative distribution of the binder phase within the test sample. 6.3 Measurement of magnetic saturation is affected by test sample size and shape, especially aspect ratio, and the compo- sition of the binder phase, that is, a mixture of ferromagnetic elements of varying intrinsic magnetic moments. 6.4 Small test samples or test samples containing relatively low concentrations of the binder phase may be immeasurable in that the low concentration prohibits detection by the field sensing coils of the specific apparatus employed.
8. Standards
8.1 No certified cemented carbide standards, powder mate- rials or sintered product, are available for magnetic saturation measurement. Most common practice is the development of (internal) reference materials representative of the test samples being evaluated. 8.2 Pure ferromagnetic materials such as nickel (Ni) or iron (Fe) with known magnetic moments are recommended for calibration of the instrumentation.