【国外标准】 Standard Specification for Tungsten Base, High-Density Metal

This specification establishes the requirements for four classes of machinable, high-density tungsten base metal produced by consolidating metal powder mixtures, the composition of which is mainly tungsten. This material specification may be used for bare parts or for parts that may be coated with other materials for protection against corrosion and abrasion; intended for uses such as weights or counter-balances in static or dynamic balancing, high-speed rotating inertia members, radiation shielding, hypervelocity impact, and vibration-damping applications. The chemical; physical properties, such as microstructure and machinability; mechanical properties, such as tensile strength, yield strength, elongation, and hardness; and composition requirements, such as density; are detailed.1.1 This specification covers the requirements for four classes of machinable, high-density tungsten base metal produced by consolidating metal powder mixtures, the composition of which is mainly tungsten. This material specification may be used for bare parts or for parts that may be coated with other materials for protection against corrosion and abrasion.1.2 This specification describes physical, mechanical, and microstructural testing of a material lot based on the use of test coupons, not actual parts. Sintered properties typically vary both with part size and sampling location within a given part. Results obtained from coupon testing may therefore differ from the properties of a specific location in a larger part.1.3 Intended Use—Parts made from this material are intended for uses such as weights or counter-balances in static or dynamic balancing, high-speed rotating inertia members, radiation shielding, hypervelocity impact, and vibration-damping applications. In selecting the appropriate alloy for a given application, it is important to note that as the tungsten content of the alloy is increased, stiffness, radiation attenuation, and density increase with an accompanying decrease in attainable ductility.1.4 Special Applications—For particular applications, properties or requirements other than those specified in Sections 5, 6, and 7 of this specification may be important. These alloys may contain elements which make them weakly ferromagnetic. Where freedom from magnetic response is required, this should be specified in the purchase order. Class 4 is not available in a non-magnetic grade. For purposes of this specification, non-magnetic material is defined as material having a maximum magnetic permeability of 1.05 (see Test Method A342). Also for special applications involving large sections, methods for determining internal quality, such as mechanical testing of specimens excised from these larger sections or suitable nondestructive tests may be applied. If such part property data are required, an additional part-specific test program shall be specified in the purchase order.1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.