ASTM B849-2019 pdf free download

ASTM B849-2019 pdf free download.Standard Specification for Pre-Treatments of Iron or Steel for Reducing Risk of Hydrogen Embrittlement
1. Scope
1.1 This specification covers procedures for reducing the susceptibility or degree ofsusceptibility to hydrogen embrittle- ment or degradation that may arise in electroplating, autocata- lytic plating, porcelain enameling, chemical conversion coating, and phosphating and the associated pretreatment processes. This specification is applicable to those steels whose properties are not affected adversely by baking at 190 to 230 °C or higher (see 6.1.1). 1.2 The heat treatment procedures established herein have been shown to be effective for reducing the susceptibility of steel parts of tensile strength 1000 MPa or greater that have been machined, ground, cold-formed, or cold-straightened subsequent to heat treatment. This heat-treatment procedure is used prior to any operation capable of hydrogen charging the parts, such as the cleaning procedures prior to electroplating, autocatalytic plating, porcelain enameling, and other chemical coating operations. N OTE 1—1 MPa = 145.1 psi. 1.3 This specification has been coordinated with ISO/DIS 9587 and is technically equivalent. 1.4 The values stated in SI units are to be regarded as the standard. 1.5 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. 1.6 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. Requirements
4.1 Heat treatment shall be performed on basis metals to reduce the risk of hydrogen embrittlement in accordance with Table 1. The duration of heat treatment shall commence in all cases from the time at which the whole of each part attains the specified temperature. 4.2 Parts made from steel with actual tensile strengths ≥1000 MPa (with corresponding hardness values of 300 HV 10kgf , 303 HB, or 31 HR c ) and surface-hardened parts shall require heat treatment unless Class SR-0 is specified. Preparation involving cathodic treatments in alkaline or acid solutions shall be avoided. 4.3 Table 1 lists the stress-relief heat-treatment classes to be specified by the purchaser to the electroplater, supplier, or processor on the part drawing or purchase order. When no stress relief treatment class is specified by the purchaser, Class SR-1 shall be applied (see Note 4). N OTE 2—The treatment class selected is based on experience with the part, or similar parts, and the specific alloy used or with empirical test data. Because of factors such as alloy composition and structure, size, mass, or design parameters, some parts may perform satisfactorily with no stress relieftreatment. Class SR-0 treatment is therefore provided for parts that the purchaser wishes to exempt from treatment. N OTE 3—The use of inhibitors in acid pickling baths is not necessarily guaranteed to minimize hydrogen embrittlement. N OTE 4—Class SR-1, the longest treatment, is the default when the purchaser does not specify a class. The electroplater, supplier, or processor is not normally in possession of the necessary information, such as design considerations, induced stresses from manufacturing operations, etc., that must be considered when selecting the correct stress relief treatment. It is in the purchasers’ interest that their part designer, manufacturing engineer, or other technically qualified individual specify the treatment class on the part drawing or purchaser order in order to avoid the extra cost of the default treatment.