1、Designation: A1091/A1091M 161Standard Specification forSteel Castings, Creep-Strength Enhanced Ferritic Alloy, forPressure-Containing Parts, Suitable for High TemperatureService1This standard is issued under the fixed designation A1091/A1091M; the number immediately following the designation indicat
2、es theyear of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTETable 3 was editorially corrected in April 2017.1. S
3、cope1.1 This specification covers creep-strength enhanced alloysteel castings for valves, flanges, fittings, and other pressure-containing parts intended primarily for high-temperature ser-vice (see Note 1). However, they are not restricted to suchapplications, and the castings may be used for other
4、 applica-tions for which the attributes of the material, as defined by thisspecification, are suitable.1.2 One grade of martensitic alloy steel, Grade C91, iscovered (see Note 2). It is provided in two classes, differenti-ated by the type of heat treatment after weld repairs. This andsimilar steels
5、are characterized by a predominantly temperedmartensitic or tempered Bainitic microstructure that is stabi-lized by the precipitation of temper-resistant particles atvarious precipitate nucleation sites in the microstructure. Suchsteels are designed to have creep-rupture strengths significantlysuper
6、ior to those of alloys of nominally similar compositions,but in which the precipitates or nucleation sites are absent.Since this crucial difference cannot be revealed by room-temperature mechanical property tests, these alloys requiretighter controls on manufacturing and processing.NOTE 1The grades
7、covered by this specification represent materialsthat are generally suitable for assembly with other castings or wroughtsteel parts by fusion welding. It is not intended to imply that these gradespossess equal degrees of weldability; therefore, it is the responsibility ofthe purchaser to establish a
8、 suitable welding technique. Since these gradespossess varying degrees of suitability for high-temperature service, it isalso the responsibility of the purchaser to determine which grade shall befurnished, due consideration being given to the requirements of theapplicable construction codes.NOTE 2Th
9、e committee formulating this specification has included onegrade of material that is considered to represent a type of ferritic alloysteel suitable for valves, flanges, fittings, and other pressure-containingparts. Additional alloy steels will be considered for inclusion in thisspecification by the
10、committee as the need becomes apparent.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two sys
11、tems may result in non-conformancewith the standard.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued
12、by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2A335/A335M Specification for Seamless Ferritic Alloy-Steel Pipe for High-Temperature ServiceA703/A703M Specification for Steel Castings, GeneralRequirements, for Pressure-Containing
13、PartsA802/A802M Practice for Steel Castings, Surface Accep-tance Standards, Visual ExaminationA985/A985M Specification for Steel Investment CastingsGeneral Requirements, for Pressure-Containing PartsA999/A999M Specification for General Requirements forAlloy and Stainless Steel Pipe2.2 ANSI Standards
14、3ANSI B46.1 Surface Texture2.3 ASME Boiler and Pressure Vessel Code4ASME Boiler and Pressure Vessel Code Section IASME Boiler and Pressure Vessel Code Section III1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsi
15、bility of SubcommitteeA01.18 on Castings.Current edition approved May 1, 2016. Published May 2016. DOI: 10.1520/A1091_A1091M-16E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informa
16、tion, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4Available from American Society of Mechanical Engineers (ASME), ASMEInternational Headquarters, Two Pa
17、rk Ave., New York, NY 10016-5990, http:/www.asme.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in t
18、he Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1ASME Boiler and Pressure Vessel Code Section IVASME Boiler and Pressure Vessel Code Section VIIIASME Boiler and Pres
19、sure Vessel Code Section IXASME Boiler and Pressure Vessel Code Section XII2.4 Other ASME Codes4B16.34 Valves Flanged, Threaded and Welding EndB31.1 Power PipingB31.3 Process Piping2.5 AWS Specifications5A5.5/A5.5M Low Alloy Steel Electrodes for Shielded MetalArc WeldingA5.23/A5.23M Low Alloy Steel
20、Electrodes and Fluxes forSubmerged Arc WeldingA5.28/A5.28M Low Alloy Steel Electrodes and Rods forGas Shielded Arc WeldingA5.29/A5.29M Low Allow Steel Electrodes for Flux CoredArc Welding3. General Conditions for Delivery3.1 Except for investment castings and centrifugally castpipe, castings furnish
21、ed to this specification shall conform tothe requirements of Specification A703/A703M, including anysupplementary requirements that are indicated in the purchaseorder. Failure to comply with the general requirements ofSpecification A703/A703M constitutes nonconformance withthis specification. In cas
22、e of conflict between the requirementsof this specification and Specification A703/A703M, thisspecification shall prevail.3.2 Investment castings furnished to this specification shallconform to the requirements of Specification A985/A985Mincluding any supplementary requirements that are indicated in
23、the purchase order. Failure to comply with the general require-ments of Specification A985/A985M constitutes nonconfor-mance with this specification. In case of conflict between therequirements of this specification and Specification A985/A985M, Specification A985/A985M shall prevail.3.3 Centrifugal
24、ly cast pipe furnished under this specificationshall conform to the requirements of Specification A999/A999M, including any supplementary requirements that areindicated in the purchase order. Failure to comply with thegeneral requirements of Specification A999/A999M consti-tutes nonconformance with
25、this specification. In case of con-flict between the requirements of this specification and Speci-fication A999/A999M, this specification shall prevail.4. Ordering Information4.1 Orders for material under this specification shall includethe following, as required, to describe the desired materialade
26、quately:4.1.1 Except for centrifugally cast pipe,4.1.1.1 A description of the casting by pattern number ordrawing (dimensional tolerances shall be included on thecasting drawing),4.1.1.2 Grade and Class of steel,4.1.1.3 Options in the specification (see 5.1.5, 5.2, 7.1.4,8.4, 10.3.5, and 10.3.7, 10.
27、3.8.2, and 10.3.8.3),4.1.1.4 Whether the castings are to be produced using theinvestment casting process, and4.1.1.5 The supplementary requirements desired includingthe standards of acceptance.4.1.2 Centrifugally cast pipe,4.1.2.1 Quantity (feet, centimeters, or number of lengths),4.1.2.2 Name of ma
28、terial (centrifugally cast pipe),4.1.2.3 Grade of steel,4.1.2.4 Size (outside or inside diameter and minimum wallthickness),4.1.2.5 Length (specific or random) (Section on PermissibleVariations in Length of Specification A999/A999M),4.1.2.6 End finish (Section on Ends of Specification A999/A999M),4.
29、1.2.7 Options in the specification (see 5.1.5, 5.2, 7.1.4,8.4, 10.3.5, and 10.3.7, 10.3.8.2, and 10.3.8.3),4.1.2.8 Whether the castings are to be used in ASME Boileror in ASME Codes B16.34, B31.1, B31.3, orother ASME construction codes,and,4.1.2.9 The supplementary requirements desired.5. Materials
30、and Manufacture5.1 Heat-TreatmentCastings shall be furnished in theaustenitized and tempered condition.5.1.1 Before heat treatment, castings shall be allowed tocool to a temperature below the transformation range.5.1.2 Castings shall be heat treated by heating to a tempera-ture range of 1900 to 1975
31、F 1040 to 1080C and either aircooled or accelerated cooled from the austenitizing tempera-ture by air blasting or liquid quenching, to a temperature of200F 95C or below, followed by tempering at 1350 to1470F 730 to 800C.5.1.3 Compliance with the temperature ranges specified in5.1.2, for castings hea
32、t treated singly, shall be verified by athermocouple or thermocouples placed directly on the castings.5.1.4 Compliance with the temperature ranges specified in5.1.2, for castings heat treated in batches, shall be verified bythermocouples placed on selected castings in each batch.5.1.5 Unless specifi
33、ed by the purchaser, the number andlocations of thermocouples to be placed on each casting, or oncastings in each heat-treatment batch, shall be at the discretionof the producer.5.1.6 A record of the final austenitizing and tempering heattreatment, and, if specified in the order (see 10.3.7), of any
34、 andall subsequent sub-critical heat treatments, shall be made andshall be shown on the material test report. The record shallinclude both the number and locations of thermocouplesapplied to each casting, or to each heat-treatment batch ofcastings.5.2 MachiningCentrifugally cast pipe shall be machin
35、edon the inner and outer surfaces to a roughness value no greaterthan 250 in. 6.35 m arithmetical average deviation (AA)from the mean line unless otherwise specified as in ANSIB46.1.5Available from American Welding Society (AWS), 8669 NW 36 St., #130,Miami, FL 33166-6672, http:/www.aws.org.A1091/A10
36、91M 16126. Chemical Composition6.1 Heat AnalysisAn analysis of each heat shall be madeby the manufacturer to determine the weight percentages ofelements specified in Table 1. The analysis shall be made on atest sample taken from the ladle. The chemical compositionthus determined shall conform to the
37、 requirements specified inTable 1 (see Note 3).NOTE 3The role of alloying elements in the development of GradeC91has been extensively investigated. V and Cb (Nb) contribute toprecipitation strengthening by forming fine and coherent precipitation ofM(C, N)X carbo-nitrides in the ferrite matrix. V als
38、o precipitates as VNduring tempering or during creep. The two elements are more effective incombination. Therefore, the addition of strong nitride-forming elements,those with a stronger affinity for nitrogen than Cb (Nb) and V, asde-oxidation agents, interferes with these high-temperature strengthen
39、ingmechanisms.67. Mechanical Properties7.1 Tensile Testing7.1.1 One tension test shall be made from each heat per heattreatment lot. Test results shall conform to the tensile require-ments specified in Table 2.7.1.2 If a specimen is machined improperly or if flaws arerevealed by machining or during
40、testing, the specimen may bediscarded and another substituted from the same heat.7.1.3 Except as permitted by 7.1.4, and except for invest-ment castings, test coupons from which tension test specimensare prepared shall be removed from heat-treated castingprolongations.7.1.4 When agreed upon between
41、the manufacturer and thepurchaser, test coupons from which test specimens are pre-pared shall be cast as separate blocks from the same heat as thecasting represented. The test blocks shall be heat treated in thesame manner as the casting represented.7.2 Hardness TestingEach casting shall be Brinell
42、hard-ness tested in accordance with Supplementary RequirementS13 of A703/A703M; or, for investment castings, Supplemen-tary Requirement S13 of A985/A985M; or, for centrifugallycast pipe, 14.3.2 of A335/A335M, and shall have a Brinellhardness of 185 to 248 HBW.8. Quality8.1 All accessible surfaces of
43、 the castings shall be examinedvisually and shall be free of adhering sand, scale, cracks, andhot tears. Other surface discontinuities shall meet the visualacceptance standards specified in the order. Practice A802/A802M or other visual standards may be used to defineacceptable surface discontinuiti
44、es and finish. Unacceptablevisual surface discontinuities shall be removed and theirremoval verified by visual examination of the resultant cavi-ties. When methods involving high temperature are used in theremoval of discontinuities, castings shall be preheated to atleast 400F 200C.8.2 Except for ce
45、ntrifugally cast pipe, hollow castings largerthan NPS 4 DN 100, and whose internal surfaces are notaccessible to the visual examination in 8.1, shall be examinedby the ultrasonic examination prescribed in SupplementaryRequirement S7 of A703/A703M; or for investment castings,of Supplementary Requirem
46、ent S7 of A985/A985M.6Viswanathan, R. and Bakker, W. T., Materials for Ultra Supercritical FossilPower Plants, EPRI, Palo Alto, CA, 2000. TR-114750.TABLE 1 Chemical RequirementsComposition, %Grade Identification Symbol C91UNS Number J84090Carbon 0.08-0.12Manganese 0.300.60Phosphorus 0.025Sulfur 0.01
47、0Silicon 0.200.50Nickel 0.40Chromium 8.09.5Molybdenium 0.851.05ColumbiumA(Niobium)A0.0600.10Nitrogen 0.0300.070Vanadium 0.180.25Aluminum 0.02Titanium 0.01Zirconium 0.01AColumbium (Cb) and Niobium (Nb) refer to the same Element 41.TABLE 2 Tensile RequirementsGrade TensileStrength, ksiMPaYieldStrength
48、A,min, ksi MPaElongation in 2 in.50 mm., min, %BReduction ofArea, min, %C91 85 585 to11076060 415 18 45ADetermined by 0.2 % offset method.BWhen ICI test bars are used in tensile testing as provided for in SpecificationA703/A703M, the gauge length-to-reduced section diameter ratio shall be 4 to 1.A10
49、91/A1091M 16138.2.1 Castings producing a signal equal to or greater thanthe lowest signal produced by the referenced discontinuitiesshall be considered to contain defects, and they shall beidentified and separated from the acceptable castings. The areaproducing the signal may be re-examined.8.2.2 Castings containing defects shall be rejected if the testsignals were produced by imperfections that cannot be identi-fied or were produced by cracks or crack-like imperfections.8.2.3 Castings containing defects may be repaired. To be
