1、Designation: B998 17Standard Guide forHot Isostatic Pressing (HIP) of Aluminum Alloy Castings1This standard is issued under the fixed designation B998; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A nu
2、mber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide presents requirements for hot isostatic press-ing (HIP) of aluminum alloy castings. HIPing is a process inwhich components are
3、 subjected to the simultaneous applica-tion of heat and high pressure in an inert gas medium. Theprocess is to be used for the reduction of internal (non-surfaceconnected) porosity. The document is to describe the generalparameters of the HIP process, describe certification proce-dures and a descrip
4、tion that the process has been followed. It isnot intended to be a description of a heat treating procedure.This is not meant to supersede an end users specificationwhere one exists.21.2 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as standard. Thevalue
5、s stated in each system may not be exact equivalents;therefore, each system shall be used independently of the other.Combining values from the two systems may result in non-conformance with the standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with
6、its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on stand
7、ard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 The following documents of the issue in effect on thedate of c
8、asting purchase form a part of this practice to theextent referenced herein:2.2 ASTM Standards:E230/E230M Specification for Temperature-ElectromotiveForce (emf) Tables for Standardized Thermocouples2.3 AMS StandardsAMS 2750 Pyrometry3. Terminology3.1 Definitions of Terms Specific to This Standard:3.
9、1.1 autoclave, na pressure vessel used in the HIPprocess.3.1.2 hold time, ntime at required temperature and pres-sure as specified on the drawing or applicable specification.Hold time to start when pressure and all temperature hold timeload monitoring thermocouples are within specified require-ments
10、.3.1.3 hot isostatic pressing (HIP), n & va solid stateprocess whereby heat and pressure are simultaneously appliedto objects in an autoclave by way of an inert gas to reduceinternal voids and obtain desired properties. Also used as averb to describe application of the process to an object, henceHIP
11、ing, HIPed.3.1.4 inert gas, na non-reactive gas, used in HIP vesselduring pressurization.3.1.5 on-line gas analysis, nanalysis of process gas ema-nating from the autoclave. Refer to 7.6 (“Inert Gas Purity”).3.1.6 working zone, nthe volume of the heated region ofan autoclave which may be occupied by
12、castings to be hotisostatically pressed.4. Significance and Use4.1 HIP of castings should be performed in the as castcondition. Post HIP inspection of castings should result in areduction of porosity that is evident in x-ray grade andproperties.4.2 HIP will not eliminate inclusions or surface-connec
13、tedporosity in a casting.5. Ordering Information5.1 Orders for HIPing of aluminum castings under thisguide should include the following information:5.1.1 This guide designation (which includes the number,year and revision letter, if applicable).1This guide is under the jurisdiction of ASTM Committee
14、 B07 on Light Metalsand Alloys and is the direct responsibility of Subcommittee B07.01 on AluminumAlloy Ingots and Castings.Current edition approved July 1, 2017. Published July 2017. DOI: 10.1520/B0998-17.2The HIP practice described in this guide is not intended to be substituted for theheat treat
15、requirements for aluminum alloy castings, which are provided in PracticeB917/B917M Standard Practice for Heat Treatment of Aluminum-Alloy Castingsfrom All Processes. This standard Guide is not meant to supersede an end usersspecification where one exists.Copyright ASTM International, 100 Barr Harbor
16、 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 the Decision on Principles for theDevelopment of International Standards, Guides and Recommendation
17、s issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15.1.2 The quantity in pieces.5.1.3 Alloy.5.1.4 Temperature, pressure, hold time, including toler-ances.6. Equipment6.1 Autoclave:6.1.1 Autoclaves should be of the inert gas pressurizationtype, internally heated, co
18、ld wall pressure vessel.6.2 Fixtures:6.2.1 Suitable jigs, trays, or other fixtures should be pro-vided as necessary for proper handling and positioning of partsto be hot isostatic pressed. All fixtures should be made ofsuitable material which is compatible with the parts to betreated.6.3 Temperature
19、 Measurement and Control Devices:6.3.1 Temperature MeasurementTemperature measuringand recording devices should be provided for the autoclave.The devices should be of the potentiometric type, should usethermocouple sensors, and should provide permanent recordsof the temperature during the entire tre
20、atment.6.3.2 Temperature ControlA sufficient number of suitabletemperature control devices should be provided and properlyarranged in the autoclave to assure the required temperaturecontrol in the working zone. The devices should be of thepotentiometric type and should use thermocouple sensors.6.4 P
21、ressure Measurement Devices:6.4.1 Pressure measurement devices should be accurate towithin 62 % at the specified operating pressure for parts beingprocessed. The device should be capable of continuouslymonitoring and recording the pressure throughout the process.7. General7.1 All HIP equipment quali
22、fications should be the respon-sibility of the hot isostatic pressing HIP Vendor. The Vendorshould be responsible for any testing required for HIP equip-ment and should sign all necessary forms which certify thatqualification, in accordance with this guide, has been attained.7.2 Cleaning:7.2.1 Casti
23、ngs to be treated, including fixtures, should bedelivered to the Vendor clean and free of all surface contami-nants which may be detrimental to the material being treated orto autoclave components. Prior to subsequent processingcycles the Vendor should ensure that fixtures, jigs, or toolingshould be
24、 kept free of all surface contaminants which may bedetrimental to the material being treated or to the autoclavecomponents.7.3 Instrumentation:7.3.1 A minimum of three thermocouples should accom-pany the material during treatment. They should be located inthe hottest, coldest, and nominal temperatur
25、e the castings. Analternate instrumentation plan may be used with prior approvalfrom the purchaser.7.4 Pressure Environment:7.4.1 EquipmentAll pressure recording equipment shouldbe calibrated in accordance with the instrument manufacturersinstructions.7.4.2 PressureThe chamber pressure during treatm
26、entshould be as specified on the drawing or applicable specifica-tion. During the heat up and hold, the chamber pressure shouldbe continuously monitored and data should be recorded at amaximum interval of no more than five (5) minutes.7.5 Thermal Treatment:7.5.1 The times and temperatures for the th
27、ermal cycleshould be as specified on the drawing, applicable specification,or in Table 1. Note that HIP is a solid state process and shouldalways occur below an alloys solidus temperature or belowany incipient melting temperature, whichever is lower. Thetemperatures should be continuously monitored
28、and datashould be recorded at an interval that is no greater than five (5)minutes. The use of multipoint recorders with a periodicrecording of five (5) minutes maximum per thermocouple ispermitted.7.6 Inert Gas Purity:7.6.1 Prior to hot isostatic pressing, the inert gas purityemanating from the auto
29、clave should be greater than 99.70 %by volume and should satisfy the impurity limit requirementsprovided in Table 2.7.6.1.1 The inert gas emanating from the autoclave, beforehot isostatic pressing, which meets the impurity requirementsof 7.6.1, should give a dew-point of -50F, (-46C) (66 ppm) orcold
30、er at ambient temperature and pressure.7.6.1.2 Methods of gas dilution, replenishment, reuse, andpurification are allowed.7.6.2 Indication of conformance to the requirements for gaspurity should be determined by on-line gas analysis of theprocess gas.7.7 Inspection and Tests:TABLE 1 Typical Mean HIP
31、 Cycles Guidelines for Aluminum AlloysAluminum Casting AlloysMaximum Temperature inHIPing FurnaceARecommended Furnace Set PointTemperature F 25F(C 14C)BPressure psi500 psi(MPa 3 MPa)Hold Time(Mnutes, +15/-0)A201.0, A206.0 960F (516C) 925935F (496502C) 15 000 (103) 120360355.0, C355.0 990F (532C) 925
32、965F (496518C) 15 000 (103) 120360356.0, A356.0, 357.0, A357.0,E357.0, F357.01000F (538C) 925975F (496524C) 15 000 (103) 120360AEutectic melting may occur if the maximum temperature in the furnace is exceeded.BThe recommended furnace temperature set point is based on a furnace temperature uniformity
33、 of 25F (C 14C) (see 8.2.1.2).The furnace set points may be adjustedfor furnaces that demonstrate greater control of temperature variation as long as temperatures in the furnace do not exceed the maximum temperature.B998 1727.7.1 All inspections or tests required by the drawing orapplicable specific
34、ations should be performed. The results ofthese inspections or tests should meet the requirements of thedrawing or applicable specifications.7.8 Records:7.8.1 All records and test results for each hot isostaticpressing treatment should be maintained for purchaser surveil-lance as required by the cus
35、tomer, contract, or purchase order.These records should include at least the following informa-tion:(a) Purchaser identification of parts or material treated.(b) Part or material alloy designation.(c) Autoclave identification.(d) Loading procedures and part placement.(e) Instrumentation procedures i
36、ncluding thermocoupletype and placement.(f) Pressure records.(g) Temperature records.(h) Pressure media.(i) Gas analysis records.(j) Dew-point measurement records.(k) Test results.8. Quality Assurance Provisions8.1 General:8.1.1 All HIP equipment qualifications should be the re-sponsibility of the h
37、ot isostatic pressing HIP Vendor. TheVendor should be responsible for any testing required for HIPequipment and should sign all necessary forms which certifythat qualification, in accordance with this guide, has beenattained.8.2 Autoclave Qualification:8.2.1 Temperature Uniformity:8.2.1.1 All autocl
38、aves should be qualified for working zonetemperature uniformity prior to use for production hot isostaticpressing. All autoclaves should be requalified at least once peryear after initial qualification. Qualification may be performedon a production load in accordance with 8.2.1.3. The procedurefor q
39、ualification, requalification, and qualification after majorchange are all the same.8.2.1.2 After thermal equilibrium is reached, the maximumtemperature variation of any load thermocouple should notdeviate from the selected control temperature by more than625F (614C).8.2.1.3 Qualification ProcedureQ
40、ualification procedurefor temperature uniformity should be documented, using afurnace load containing a representative production load ofparts. Furnace qualification should conform to the require-ments of AMS 2750 using customer accepted temperatureuniformity survey(s) done by the HIP vendor. After
41、initialqualification the furnace should be requalified at least every six(6) months using an agreed upon procedure between purchaserand HIP vendor.8.3 Temperature Measurement and Control Qualification:8.3.1 InstrumentsThe temperature control system shouldhave an accuracy of 60.5 % of the maximum ope
42、ratingtemperature. The temperature accuracy of each instrumentshould be determined in accordance with the equipmentmanufacturers recommendations. After the initialqualification, all instruments should be requalified at leastevery 90 days.8.3.2 ThermocouplesBefore each use, all thermocouplesshould be
43、 capable of meeting the temperature/electromotiveforce requirements of Specification E230/E230M tables forspecial grade wire as determined by suitable test methods andrequalification intervals.8.4 Pressure Indicating Instrument QualificationAll pres-sure indicating instruments should be checked in a
44、ccordancewith the equipment manufacturers recommendations. Theequipments performance should be within the limits suppliedby the equipment manufacturer. After the initial qualification,each instrument should be requalified at least every 90 days orthe controlling specification requirement.8.5 Process
45、 Qualification:8.5.1 Castings should be processed only by a HIP sourceapproved by the purchaser.8.5.2 If required, before production processing, detailedprocess procedures and results of test samples may be submit-ted to the purchaser for approval.8.5.3 Process procedures should include the same inf
46、orma-tion as required in 7.8.1.9. Keywords9.1 aluminum casting; autoclave; densification; HIP; HIP-ing; hot isostatic pressing; internal voids; inert gases; porosity;pressure; thermal couple; thermal treatmentTABLE 2 Allowable Inert Gas ImpuritiesImpurityMaximum VolumePresentPPM (Vol/Vol)Nitrogen 0.
47、0050 50Hydrogen 0.0125 125Oxygen 0.0025 25Hydrocarbons (Methane, CH4) 0.0025 25B998 173ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of
48、the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Y
49、our comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box
