1、Designation: A 320/A 320M 07aStandard 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 cas
2、e 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 spe
3、cification2covers 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 isthoroug
5、hly 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 th
6、e 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 specifi
7、ed 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 includeds
8、everal 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 siz
9、e 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 i
10、nquiry, contract and order.1.5 This specification is expressed in both inch-pound unitsand in SI units. However, unless the order specifies theapplicable “M” specification designation (SI units), the mate-rial shall be furnished to inch-pound units.1.6 The values stated in either inch-pound units or
11、 SI unitsare to be regarded separately as standard. Within the text, theSI 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
12、 specifi-cation.2. Referenced Documents2.1 ASTM Standards:3A 194/A 194M Specification 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 Requirem
13、entsfor Steel Fasteners or Fastener Materials, or Both, Intendedfor Use at Any Temperature from Cryogenic to the CreepRangeE 566 Practice for Electromagnetic (Eddy-Current) Sortingof Ferrous MetalsF 436 Specification for Hardened Steel Washers1This specification is under the jurisdiction of ASTM Com
14、mittee 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 for Piping and Special Purpose Applications.Current edition approved Sept. 1, 2007. Published October 2007.
15、 Originallyapproved in 1948. Last previous edition approved in 2007 as A 320/A 320M-07.2For ASME Boiler and Pressure Vessel Code applications, see related Specifi-cation SA-320 in Section II of that Code.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Se
16、rvice 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 this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19
17、428-2959, United States.F 606 Test Methods for Determining the Mechanical Prop-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 responsibil
18、ity to specify in thepurchase order all information necessary to purchase theneeded 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); s
19、olution-treated afterfinishing (Class 1A); and annealed and strain-hardened (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
20、.1.3, and 12.1.4. Common Requirements4.1 Material and fasteners supplied to 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. Failu
21、re to comply with the requirements ofSpecification A 962/A 962M constitutes 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 ma
22、y bethe tempering operation if conducted at 1150 F 620 Cminimum, shall be done 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
23、 or forging. Grades L7, L7A, L7B,L7C, L7M, L43, L1, L70, L71, L72, and L73 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 de
24、scribed as Class 1. Thisshall consist of holding the material for a sufficient 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 Cla
25、ss 1. If specified in the purchaseorder, material shall be solution treated 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 t
26、he purchase order; material sotreated is identified as Class 2.5.1.3 If scale-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
27、be done after machining orrolling of the threads and any type of cutting.6. 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
28、(see 5.1.1). Alternatively, Class 2 Strain Hardened HeadedFasteners shall be 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 speci
29、men tests,full size test results shall prevail.6.1.2 Number of Tests:6.1.2.1 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 bede
30、fined as 6000 lb 2700 kg.6.1.2.2 For studs, bolts, screws, etc., one tension 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 thereof
31、Over 118 30 to 134 45,incl4500 2040 or fractionthereofOver 134 45 to 212 65,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,
32、 and which areproduced by upsetting or forging (hot or cold) shall besubjected 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
33、failure, or indicationsof failure, such as cracks, at the junction of the head 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
34、the tensile strengthshown in Table 1. The minimum full size breaking strength(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 07a2TABLE1Mechanica
35、lRequirementsClassandGrade,Diameter,inmmHeatTreatmentMinimumTemperingTemperatureFCTensileStrength,min,ksiMPaYieldStrength,min,ksiMPa(0.2%offset)Elongationin2in.or50mmmin,%ReductionofArea,min,%HardnessmaxFerriticSteelsL7,L7A,L7B,L7C,L70,L71,L72,L731251051650321HBor35HRC21265andunderAquenchedandtemper
36、ed1100593860725L431251051650321HBor35HRC4100andunderAquenchedandtempered1100593860725L7M100801850235HBBor99HRB21265andunderAquenchedandtempered1150620690550L11251051650.125andunderAquenchedandtempered860725AusteniticSteelsCClass1:B8,B8C,B8M,B8P,B8F,B8T,B8LN,B8MLN,alldiameterscarbidesolutiontreated75
37、515302053050223HBDor96HRBClass1A:B8A,B8CA,B8MA,B8PA,B8FA,B8TA,B8LNA,B8MLNA,alldiameterscarbidesolutiontreatedinthefinishedcondition75515302053050192HBor90HRBClass2:B8,B8C,B8P,B8F,B8T:carbidesolutiontreatedandstrainhardened3420andunder1258601006901235321HBor35HRCover34to120to25,incl115795805501530321
38、HBor35HRCover1to11425to32,incl105725654502035321HBor35HRCover114to11232to40,inclA100690503452845321HBor35HRCClass2:B8M:carbidesolutiontreatedandstrainhardened3420andunder110760956551545321HBor35HRCover34to120to25,incl100690805502045321HBor35HRCover1to11425to32,incl95655654502545321HBor35HRCover114to
39、11232to40,inclA90620503453045321HBor35HRCATheseupperdiameterlimitswereestablishedonthebasisthatthesewerethelargestsizescommonlyavailablethatconsistentlymetspecificationpropertylimits.Theyarenotintendedasabsolutelimitsbeyondwhichboltingmaterialscouldnolongerbecertifiedtothespecification.BTomeettheten
40、silerequirements,theBrinellhardnessshallnotbelessthan200HBor93HRB.CClass1productsaremadefromsolution-treatedmaterial.Class1Aproductsaresolutiontreatedinthefinishedconditionforcorrosionresistance;heattreatmentiscriticalforenhancingthisphysicalpropertyandmeetingthemechanicalpropertyrequirements.Class2
41、productsaremadefromsolution-treatedmaterialthathasbeenstrainhardened.Austeniticsteelsinthestrain-hardenedconditionmaynotshowuniformpropertiesthroughoutthecrosssection,particularlyinsizesover34in.20mmindiameter.DForsizes34in.20mmindiameterandsmaller,amaximumhardnessof241HB(100HRB)ispermitted.A 320/A
42、320M 07a3where:Ts = Wedge tensile strengthUTS = Tensile strength specified in 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 Requireme
43、nts:6.2.1.1 Material of Grades L7, L7A, L7B, L7C, L7M, L43,L70, L71, L72, and 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
44、 of Sections 19 to 28 of Test Methods andDefinitions A 370. The temperature of 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 temperatu
45、res above 325 F 200C; for carbide solution treated Grades B8, B8P, B8C, andB8LN 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
46、are listed inTable 3. Exceptions to this requirement are permissible, and theimpact 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
47、reported test temperature.When impact testing is required for austenitic grades, 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
48、 requirements for heat-treated bars are givenin 6.1.2.1.6.2.2.2 For test requirements 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 secti
49、ons 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 Hardness Requirements:6.3.1 The hardness shall conform to the requirements pre-scribed in Table 1. Hardness testing shall be performed inaccordance with either Specification A 962/A 962M or withTest Methods F 606.6.3.2 The
