1、Designation: A988/A988M 16A988/A988M 17Standard Specification forHot Isostatically-Pressed Stainless Steel Flanges, Fittings,Valves, and Parts for High Temperature Service1This standard is issued under the fixed designation A988/A988M; the number immediately following the designation indicates the y
2、earof original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This specification covers hot isostatically-pressed,
3、 powder metallurgy, stainless steel piping components for use in pressuresystems. Included are flanges, fittings, valves, and similar parts made to specified dimensions or to dimensional standards, suchas in ASME specification B16.5.1.2 Several grades of martensitic, austenitic, age hardening, and a
4、ustenitic-ferritic stainless steels are included in thisspecification.1.3 Supplementary requirements are provided for use when additional testing or inspection is desired. These shall apply onlywhen specified individually by the purchaser in the order.1.4 This specification is expressed in both inch
5、-pound units and in SI units. Unless the order specifies the applicable “M”specification designation (SI units), however, the material shall be furnished to inch-pound units.1.5 The values stated in either inch-pound units or SI units are to be regarded separately as the standard. Within the text, t
6、heSI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be usedindependently of the other. Combining values from the two systems may result in non-conformance with the standard.1.6 The following safety hazards caveat pertains only
7、 to test methods portions 8.1, 8.2, 9.5 9.7, and Section 10 of thisspecification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appropriate safety and health practices and deter
8、mine the applicability ofregulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations i
9、ssuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2A262 Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless SteelsA275/A275M Practice for Magnetic Particle Examination of Steel ForgingsA745/A7
10、45M Practice for Ultrasonic Examination of Austenitic Steel ForgingsA751 Test Methods, Practices, and Terminology for Chemical Analysis of Steel ProductsA923 Test Methods for Detecting Detrimental Intermetallic Phase in Duplex Austenitic/Ferritic Stainless SteelsA961/A961M Specification for Common R
11、equirements for Steel Flanges, Forged Fittings, Valves, and Parts for PipingApplicationsB311 Test Method for Density of Powder Metallurgy (PM) Materials Containing Less Than Two Percent PorosityE112 Test Methods for Determining Average Grain SizeE165E165/E165M Practice for Liquid Penetrant Examinati
12、on for General IndustryE340 Practice for Macroetching Metals and AlloysE606E606/E606M Test Method for Strain-Controlled Fatigue Testing1 This specification is under the jurisdiction ofASTM Committee A01 on Steel, Stainless Steel and RelatedAlloys and is the direct responsibility of Subcommittee A01.
13、22onSteel Forgings and Wrought Fittings for Piping Applications and Bolting Materials for Piping and Special Purpose Applications.Current edition approved May 1, 2016May 1, 2017. Published May 2016May 2017. Originally approved in 1998. Last previous edition approved in 20152016 asA988/A988M 15a.A988
14、/A988M 16. DOI: 10.1520/A0988_A0988M-16.10.1520/A0988_A0988M-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM websi
15、te.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior
16、editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-
17、2959. United States1G48 Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and RelatedAlloys by Use of Ferric ChlorideSolution2.2 MSS Standard:SP 25 Standard Marking System for Valves, Fittings, Flanges, and Unions32.3 ASME Specifications and Boiler and Pressure Vessel Cod
18、es:B16.5 Dimensional Standards for Steel Pipe Flanges and Flanged Fittings 42.4 ASME Specification IX Welding Qualifications:SFA-5.4 Specification for Corrosion-Resisting Chromium and Chromium-Nickel Steel Covered Welding Electrodes4SFA-5.9 Specification for Corrosion-Resisting Chromium and Chromium
19、-Nickel Steel Welding Rods and Bare Electrodes4SFA-5.11 Specification for Nickel and Nickel-Alloy Covered Welding Electrodes4SFA-5.14 Specification for Nickel and Nickel Alloy Bare Welding Electrodes and Rods42.5 AWS Standard:5A5.11 Specification for Nickel and Nickel Alloy Welding Electrodes for Sh
20、ielded Metal Arc WeldingA5.14 Specification for Nickel and Nickel Alloy Bare Welding Electrodes and Rods3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 can, nthe container used to encapsulate the powder during the pressure consolidation process; it is partially or fullyremoved
21、 from the final part.3.1.2 compact, nthe consolidated powder from one can. It may be used to make one or more parts.3.1.3 consolidation, nthe bonding of adjacent powder particles in a compact under pressure by heating to a temperature belowthe melting point of the powder.3.1.4 fill stem, nthe part o
22、f the compact used to fill the can. It is not usually integral to the part produced.3.1.5 hot isostatic-pressing, na process for simultaneously heating and forming a compact in which the powder is containedin a sealed formable enclosure usually made from metal and the so-contained powder is subjecte
23、d to equal pressure from alldirections at a temperature high enough to permit plastic deformation and consolidation of the powder particles to take place.3.1.6 lot, na number of parts made from a single powder blend following the same manufacturing practice.3.1.7 part, na single item coming from a c
24、ompact, either prior to or after machining.3.1.8 powder blend, na homogeneous mixture of powder from one or more heats of the same grade.3.1.9 rough part, nthe part prior to final machining.4. Ordering Information4.1 It is the responsibility of the purchaser to specify in the purchase order all requ
25、irements that are necessary for materialordered under this specification. Such requirements may include, but are not limited to, the following:4.1.1 Quantity (weight or number of parts),4.1.2 Name of material or UNS number,4.1.3 ASTM designation and year of issue,4.1.4 Dimensions (tolerances and sur
26、face finishes should be included),4.1.5 Microstructure examination if required (5.1.4),4.1.6 Inspection (15.1),4.1.7 Whether rough part or finished machined part (8.2.2),4.1.8 Supplementary requirements, if any,4.1.9 Additional requirements (See 7.2 and 17.1), and4.1.10 Requirement, if any, that the
27、 manufacturer shall submit drawings for approval showing the shape of the rough part beforemachining and the exact location of test specimen material (See 9.3).5. Materials and Manufacture5.1 Manufacturing Practice:3 Available from Manufacturers Standardization Society of the Valve and Fittings Indu
28、stry (MSS), 127 Park St., NE, Vienna, VA 22180-4602, http:/www.mss-.4 Available from American Society of Mechanical Engineers (ASME), ASME International Headquarters, Two Park Ave., New York, NY 10016-5990, http:/www.asme.org.5 Available from American Welding Society (AWS), 8669 NW 36 St., #130, Mia
29、mi, FL 33166-6672, http:/www.aws.org.A988/A988M 1725.1.1 Compacts shall be manufactured by placing a single powder blend into a can, evacuating the can, and sealing it. The canmaterial shall be selected to ensure that it has no deleterious effect on the final product. The entire assembly shall be he
30、ated andplaced under sufficient pressure for a sufficient period of time to ensure that the final consolidated part meets the densityrequirements of 8.1.1.1. One or more parts shall be machined from a single compact.5.1.2 The powder shall be prealloyed and made by a melting method capable of produci
31、ng the specified chemical composition,such as but not limited to, air or vacuum induction melting, followed by gas atomization.5.1.3 When powder from more than one heat of the same grade is used to make a blend, the heats shall be mixed thoroughlyto ensure homogeneity.5.1.4 The compact shall be sect
32、ioned and the microstructure examined to check for porosity and other internal imperfections.It shall meet the requirements of 8.1.2. The sample shall be taken from the fill stem or from a location in a part as agreed uponby the manufacturer and purchaser.5.1.5 Unless otherwise specified in the purc
33、hase order, the manufacturer shall remove the can material from the surfaces of theconsolidated compacts by chemical or mechanical methods such as by pickling or machining. This removal shall be done beforeor after heat treatment at the option of the manufacturer (See Note 1).NOTE 1Often, it is adva
34、ntageous to leave the can material in place until after heat treatment or further thermal processing of the consolidated compact.6. Chemical Composition6.1 The steel, both as a blend and as a part, shall conform to the requirements for chemical composition prescribed in Table 1.Test Methods, Practic
35、es, and Terminology of A751 shall apply.6.1.1 A representative sample of each blend of powder shall be analyzed by the manufacturer to determine the percentage ofelements prescribed in Table 1. The blend shall conform to the chemical composition requirements prescribed in Table 1.6.1.2 When required
36、 by the purchaser, the chemical composition of a sample from one part from each lot of parts shall bedetermined by the manufacturer. The composition of the sample shall conform to the chemical requirements prescribed in Table1.6.2 Addition of lead, selenium, or other unspecified elements for the pur
37、pose of improving the machinability of the compactshall not be permitted.6.3 The steel shall not contain an unspecified element other than nitrogen, for the ordered grade, to the extent that the steelconforms to the requirements of another grade for which that element is a specified element having a
38、 required minimum content.7. Heat Treatment7.1 Except as provided in 7.2, the final heat treatment of all parts shall be in compliance with the requirements of Table 2.Afterhot isostatic-pressing and prior to final heat treatment, the compacts are permitted to be annealed, at the option of the produ
39、cer,either as a part of the consolidation process or as a separate operation.7.2 When agreed upon by the purchaser, liquid quenching may be applied to the martensitic stainless steels in place of thefurnace cool or air cool specified in Table 2, provided that such quenching is followed by tempering
40、in the temperature ranges asrequired in Table 2. Martensitic parts that are liquid quenched and tempered shall be marked “QT.”7.3 The final heat treatment shall be performed before or after machining at the option of the producer.7.4 See Section S16 if a particular heat treatment method is specified
41、 by the purchaser in the purchase order.8. Structural Integrity Requirements8.1 MicroporosityThe parts shall be free of microporosity as demonstrated by measurement of density as provided in 8.1.1or by microstructural examination as provided in 8.1.2.8.1.1 Density Measurement:8.1.1.1 The density mea
42、surement shall be used for acceptance of material but not for rejection of material.The measured densityfor each production lot shall exceed 99 % of the density typical of that grade when wrought and in the same heat treated conditionas the sample. A production lot that fails to meet this acceptance
43、 criterion is permitted to be tested at the option of the producer,for microporosity in accordance with the microstructural examination as provided in 8.1.2.8.1.1.2 Density shall be determined for one sample from each production lot by measuring the difference in mass of the samplewhen weighed in ai
44、r and when weighed in water and multiplying this difference by the density of water (Archimedes principle).The equipment used shall be capable of determining density within 60.004 lb/in.3 0.10 g/cm3. Alternatively, at the option of theproducer, it is permitted to use Test Method B311 to determine th
45、e density.8.1.1.3 At the option of the producer, the density shall be compared to the room temperature density typical of wrought steelsof the same class of grades, 0.28 lb/in.3 7.8 g/cm3 for age-hardening, martensitic, and austenitic-ferritic grades, and 0.29lb/in.3 8.0 g/cm3 for austenitic grades,
46、 or to the density of a wrought reference sample of the same grade heat treated inaccordance with the requirements of Table 2 (See Note 2).NOTE 2The actual density of stainless steel varies slightly with composition and heat treatment. For this reason, small differences in the measuredA988/A988M 173
47、TABLE 1 Chemical RequirementsComposition, %AUNSDesignation Grade Carbon Manganese Phosphorus Sulfur Silicon Nickel Chromium Molybdenum Copper NiobiumE Nitrogen OtherElementsMartensitic Stainless SteelsS41000 13 chromium 0.15 1.00 0.040 0.030 1.00 11.513.5 . . . . . . . . . . . .S41026 13 chromium 0.
48、15 1.00 0.020 0.020 1.00 1.002.00 11.513.5 0.400.60 0.50 . . .0.5 molybdenumS41500 13 chromium, 4 0.05 0.501.00 0.030 0.030 0.60 3.55.5 11.514.0 0.501.00 . . . . . . . . .nickelS42390 12 chromium, 1.0molybdenum,modified withvanadium0.180.25 1.00 0.030 0.030 1.00 0.300.80 11.512.5 0.801.20 . . . 0.08
49、0.15 0.030.08 V0.250.35Austenitic Stainless SteelsN08028 32 nickel, 27chromium, 3.5molybdenum0.030 2.50 0.030 0.030 1.0 30.034.0 26.028.0 3.04.0 0.601.4 . . . . . .N08029 32 nickel, 27chormium, 4.5molybdenum0.020 2.0 0.025 0.015 0.6 30.034.0 26.028.0 4.05.0 0.601.4 . . . . . .S30400B 18 chromium, 8nickel0.08 2.00 0.045 0.030 1.00 8.011.0 18.020.0 . . . . . . . . . . . .S30403B 18 chromium, 8nickel,low carbon0.035 2.00 0.045 0.030 1.00 8.013.0 18.020.0 . . . . . . . . . . . .S30451C 18 chromium, 8nickel,modified withnitro
