1、Designation: A 320/A 320M 08Standard Specification forAlloy-Steel and Stainless Steel Bolting Materials for Low-Temperature Service1This standard is issued under the fixed designationA 320/A 320M; the number immediately following the designation indicates the yearof original adoption or, in the case
2、 of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This spec
3、ification2covers alloy steel bolting materialsfor pressure vessels, valves, flanges, and fittings for low-temperature service. The term “bolting material” as used in thisspecification covers rolled, forged, or strain hardened bars,bolts, screws, studs, and stud bolts. The bars shall be hot-wrought.
4、The material may be further processed by centerlessgrinding or by cold drawing. Austenitic stainless steel may besolution annealed or annealed and strain-hardened. Whenstrain hardened austenitic stainless steel is ordered, the pur-chaser should take special care to ensure that Appendix X1 isthorough
5、ly understood.1.2 Several grades are covered, including both ferritic andaustenitic steels designated L7, B8, etc. Selection will dependon design, service conditions, mechanical properties, andlow-temperature characteristics. The mechanical requirementsof Table 1 indicate the diameters for which the
6、 minimummechanical properties apply to the various grades and classes,and Table 2 stipulates the requirements for Charpy impactenergy absorption. The manufacturer should determine that thematerial can conform to these requirements before parts aremanufactured. For example, when Grade L43 is specifie
7、d tomeet the Table 2 impact energy values at 150 F 101 C,additional restrictions (such as procuring a steel with lower Pand S contents than might normally be supplied) in thechemical composition for AISI 4340 are likely to be required.NOTE 1The committee formulating this specification has includedse
8、veral grades of material that have been rather extensively used for thepresent purpose. Other compositions will be considered for inclusion bythe committee from time to time as the need becomes apparent. Usersshould note that hardenability of some of the grades mentioned mayrestrict the maximum size
9、 at which the required mechanical properties areobtainable.1.3 Nuts for use with this bolting material are covered inSection 10 and the nut material shall be impact tested.1.4 Supplementary Requirements (S1, S2, and S3) of anoptional nature are provided. They shall apply only whenspecified in the in
10、quiry, contract and order.1.5 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 systems may resu
11、lt in non-conformancewith the standard. Unless the order specifies the applicable“M” specification designation (SI units), the material shall befurnished to inch-pound units.1.6 The values stated in either inch-pound units or SI unitsare to be regarded separately as standard. Within the text, theSI
12、units are shown in brackets. The values stated in eachsystem are not exact equivalents; therefore, each system mustbe used independently of the other. Combining values from thetwo systems may result in nonconformance with the specifi-cation.2. Referenced Documents2.1 ASTM Standards:3A 194/A 194M Spe
13、cification for Carbon and Alloy SteelNuts for Bolts for High Pressure or High TemperatureService, or BothA 370 Test Methods and Definitions for Mechanical Testingof Steel ProductsA 962/A 962M Specification for Common Requirementsfor Steel Fasteners or Fastener Materials, or Both, Intendedfor Use at
14、Any Temperature from Cryogenic to the CreepRange1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.22 on Steel Forgings and Wrought Fittings for PipingApplications and BoltingMaterials fo
15、r Piping and Special Purpose Applications.Current edition approved March 15, 2008. Published April 2008. Originallyapproved in 1948. Last previous edition approved in 2007 as A 320/A 320M-07a.2For ASME Boiler and Pressure Vessel Code applications, see related Specifi-cation SA-320 in Section II of t
16、hat Code.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of
17、 this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.E 566 Practice for Electromagnetic (Eddy-Current) Sortingof Ferrous MetalsF 436 Specification for Hardened Steel WashersF 606 Test Methods for Determining the Mechanical P
18、rop-erties of Externally and Internally Threaded Fasteners,Washers, Direct Tension Indicators, and Rivets2.2 ANSI Standards:B1.1 Screw Threads4B18.22.1 Plain Washers43. Ordering Information3.1 It is the purchasers responsibility to specify in thepurchase order all information necessary to purchase t
19、heneeded materials. Examples of such information include, butare not limited to, the following:3.1.1 Quantity and size,3.1.2 Heat-treated condition, that is, for the austenitic stain-less steels, solution-treated (Class 1); solution-treated afterfinishing (Class 1A); and annealed and strain-hardened
20、 (Class2),3.1.3 Description of items required (bars, bolts, screws, orstuds),3.1.4 Nuts and washers, if required by the purchaser, inaccordance with Section 10, and3.1.5 Special requirements, in accordance with 5.1.1, 5.1.2,5.1.3, and 12.1.4. Common Requirements4.1 Material and fasteners supplied to
21、 this specification shallconform to the requirements of Specification A 962/A 962M.These requirements include methods, finish, thread dimen-sions, marking certification, optional supplementary require-ments, and others. Failure to comply with the requirements ofSpecification A 962/A 962M constitutes
22、 nonconformance withthis specification. In case of conflict between the requirementsin this specification and Specification A 962/A 962M, thisspecification shall prevail.4.2 For L7M bolting, the final heat treatment, which may bethe tempering operation if conducted at 1150 F 620 Cminimum, shall be d
23、one after machining and forming opera-tions, including thread rolling and any type of cutting.5. Materials and Manufacture5.1 Heat Treatment:5.1.1 The bolting material shall be allowed to cool to roomtemperature after rolling or forging. Grades L7, L7A, L7B,L7C, L7M, L43, L1, L70, L71, L72, and L73
24、shall be reheatedto above the upper critical temperature and liquid quenchedand tempered. Grades B8, B8C, B8M, B8T, B8F, B8P, B8LN,and B8MLN shall receive a carbide solution treatment. Prod-ucts made from such material are described as Class 1. Thisshall consist of holding the material for a suffici
25、ent time at atemperature at which the chromium carbide will go intosolution and then cooling in air or in a liquid medium at a ratesufficient to prevent reprecipitation of the carbide. Materialthus treated is described as Class 1. If specified in the purchaseorder, material shall be solution treated
26、 in the finished condi-tion; material so treated is described as Class 1A.5.1.2 When increased mechanical properties are desired, theaustenitic bolting materials shall be solution annealed andstrain hardened if specified in the purchase order; material sotreated is identified as Class 2.5.1.3 If sca
27、le-free bright finish is required, this shall bespecified in the purchase order.5.1.4 For L7M bolting, the final heat treatment, which maybe the tempering or stress-relieving operation conducted at1150 F 620 C minimum, shall be done after machining orrolling of the threads and any type of cutting.6.
28、 Mechanical Requirements6.1 Tensile Properties:6.1.1 The material as represented by the tension specimensshall conform to the requirements as to tensile propertiesprescribed in Table 1 at room temperature after heat treatment(see 5.1.1). Alternatively, Class 2 Strain Hardened HeadedFasteners shall b
29、e tested full size after strain hardening todetermine tensile strength and yield strength and shall conformto the requirements prescribed in Table 1. Should the results offull size tests conflict with results of tension specimen tests,full size test results shall prevail.6.1.2 Number of Tests:6.1.2.
30、1 For heat-treated bars, one tension test and oneimpact test consisting of three specimens shall be made foreach diameter of each heat represented in each temperingcharge. In the continuous type treatment, a charge shall bedefined as 6000 lb 2700 kg.6.1.2.2 For studs, bolts, screws, etc., one tensio
31、n test andone set of three impact specimens shall be made for eachdiameter of each heat involved in the lot. Each lot shall consistof the following:Diameter, in. mm Lot Size, lb kg118 30 and under 1500 680 or fraction thereofOver 118 30 to 134 45,incl4500 2040 or fractionthereofOver 134 45 to 212 65
32、,incl6000 2700 or fractionthereofOver 212 65 100 pieces or fraction thereof6.1.2.3 Full Size Specimens, Headed FastenersHeadedfasteners 112 in. in body diameter and smaller, with bodylength three times the diameter or longer, and which areproduced by upsetting or forging (hot or cold) shall besubjec
33、ted to full size testing in accordance with 6.1.3. Thistesting shall be in addition to tensile testing as specified in6.1.1. The lot size shall be shown in 6.1.2.2. Failure shall occurin the body or threaded sections with no failure, or indicationsof failure, such as cracks, at the junction of the h
34、ead and shank.6.1.3 Full Size Fasteners, Wedge Tensile TestingWhenapplicable, see 6.1.2.3. Headed fasteners shall be wedge testedfull size in accordance with Annex A3 of Test Methods andDefinitions A 370 and shall conform to the tensile strengthshown in Table 1. The minimum full size breaking streng
35、th(lbf) for individual sizes shall be as follows:Ts 5 UTS 3 As (1)4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.A 320/A 320M 082TABLE1MechanicalRequirementsClassandGrade,Diameter,inmmHeatTreatmentMinimumTemperingTempera
36、tureFCTensileStrength,min,ksiMPaYieldStrength,min,ksiMPa(0.2%offset)Elongationin2in.or50mmmin,%ReductionofArea,min,%HardnessmaxFerriticSteelsL7,L7A,L7B,L7C,L70,L71,L72,L731251051650321HBor35HRC21265andunderAquenchedandtempered1100593860725L431251051650321HBor35HRC4100andunderAquenchedandtempered1100
37、593860725L7M100801850235HBBor99HRB21265andunderAquenchedandtempered1150620690550L11251051650.125andunderAquenchedandtempered860725AusteniticSteelsCClass1:B8,B8C,B8M,B8P,B8F,B8T,B8LN,B8MLN,alldiameterscarbidesolutiontreated75515302053050223HBDor96HRBClass1A:B8A,B8CA,B8MA,B8PA,B8FA,B8TA,B8LNA,B8MLNA,a
38、lldiameterscarbidesolutiontreatedinthefinishedcondition75515302053050192HBor90HRBClass2:B8,B8C,B8P,B8F,B8T:carbidesolutiontreatedandstrainhardened3420andunder1258601006901235321HBor35HRCover34to120to25,incl115795805501530321HBor35HRCover1to11425to32,incl105725654502035321HBor35HRCover114to11232to40,
39、inclA100690503452845321HBor35HRCClass2:B8M:carbidesolutiontreatedandstrainhardened3420andunder110760956551545321HBor35HRCover34to120to25,incl100690805502045321HBor35HRCover1to11425to32,incl95655654502545321HBor35HRCover114to11232to40,inclA90620503453045321HBor35HRCATheseupperdiameterlimitswereestabl
40、ishedonthebasisthatthesewerethelargestsizescommonlyavailablethatconsistentlymetspecificationpropertylimits.Theyarenotintendedasabsolutelimitsbeyondwhichboltingmaterialscouldnolongerbecertifiedtothespecification.BTomeetthetensilerequirements,theBrinellhardnessshallnotbelessthan200HBor93HRB.CClass1pro
41、ductsaremadefromsolution-treatedmaterial.Class1Aproductsaresolutiontreatedinthefinishedconditionforcorrosionresistance;heattreatmentiscriticalforenhancingthisphysicalpropertyandmeetingthemechanicalpropertyrequirements.Class2productsaremadefromsolution-treatedmaterialthathasbeenstrainhardened.Austeni
42、ticsteelsinthestrain-hardenedconditionmaynotshowuniformpropertiesthroughoutthecrosssection,particularlyinsizesover34in.20mmindiameter.DForsizes34in.20mmindiameterandsmaller,amaximumhardnessof241HB(100HRB)ispermitted.A 320/A 320M 083where:Ts = Wedge tensile strengthUTS = Tensile strength specified in
43、 Table 1, andAs = Stress area, square inches, as shown in ANSI B1.1or calculated as follows:As 5 0.785 D20.974/n!2(2)where:D = Nominal thread size, andn = The number of threads per inch.6.2 Impact Properties:6.2.1 Requirements:6.2.1.1 Material of Grades L7, L7A, L7B, L7C, L7M, L43,L70, L71, L72, and
44、 L73 shall show a minimum impact energyabsorption of 20 ft lbf 27 J and of Grade L1 a minimumimpact energy absorption of 40 ft lbf 54 J at the testtemperature when tested by the procedure specified in theapplicable portions of Sections 19 to 28 of Test Methods andDefinitions A 370. The temperature o
45、f the coolant used forchilling the test specimens shall be controlled within 63F1.5 C. Impact tests are not required for carbide solutiontreated or strain hardened Grades B8, B8F, B8P, B8M, B8T,B8LN, and B8MLN for temperatures above 325 F 200C; for carbide solution treated Grades B8, B8P, B8C, andB8
46、LN above 425 F 255 C; for all ferritic and austeniticsteel grades of bolting12 in. 12.5 mm and smaller indiameter. All other material furnished under this specificationshall be tested. Test temperatures for ferritic grades are listed inTable 3. Exceptions to this requirement are permissible, and the
47、impact tests may be made at specified temperatures differentthan those shown in Table 3, provided the test temperature is atleast as low as the intended service temperature and the boltingis suitably marked to identify the reported test temperature.When impact testing is required for austenitic grad
48、es, testcriteria shall be agreed upon between the supplier and pur-chaser.6.2.1.2 The impact test requirements for standard and sub-size Charpy test specimens are prescribed in Table 2.6.2.2 Number of Tests:6.2.2.1 The test requirements for heat-treated bars are givenin 6.1.2.1.6.2.2.2 For test requ
49、irements on studs, bolts, screws, etc.,see 6.1.2.2.6.2.2.3 Impact tests are not required to be made on heat-treated bars, bolts, screws, studs, and stud bolts12 in. 12.5mm and under in diameter.6.2.3 Test SpecimensFor sections 1 in. 25 mm or less indiameter, test specimens shall be taken at the axis; for sectionsover 1 in. 25 mm in diameter, midway between the axis andthe surface.6.3
