ASTM B917 B917M-2008 Standard Practice for Heat Treatment of Aluminum-Alloy Castings from All Processes.pdf

1、Designation: B 917/B 917M 08Standard Practice forHeat Treatment of Aluminum-Alloy Castings from AllProcesses1This standard is issued under the fixed designation B 917/B 917M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year

2、 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.NoteTable 1 and section 7.1 updated and the year date was changed on Aug. 7, 2008.1. Scope*1.1 This practice covers, when spec

3、ified by material speci-fication or purchase order, the heat treatment of aluminumalloy castings from all casting processes.1.1.1 The heat treatment of aluminum alloy castings used inspecific aerospace applications is covered in AMS 27712andspecific AMS2material specifications.1.1.2 The heat treatme

4、nt of wrought aluminum alloys iscovered in Practice B 918.1.2 The values stated in either inch-pound units or SI unitsare to be regarded separately as standards. The SI units areshown in brackets or in separate tables. The values stated ineach system are not exact equivalents, therefore each systemm

5、ust be used independent of the other. Combining values fromthe two systems may result in non-conformance with thepractice.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-

6、priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 The following documents of the issue in effect on thedate of material purchase form a part of this specification to theextent referenced herein:2.2 ASTM Standards:3B

7、26/B 26M Specification for Aluminum-Alloy Sand Cast-ingsB 108 Specification for Aluminum-Alloy Permanent MoldCastingsB 275 Practice for Codification of Certain Nonferrous Met-als and Alloys, Cast and WroughtB 557 Test Methods for Tension Testing Wrought and CastAluminum- and Magnesium-Alloy Products

8、B 557M Test Methods for Tension Testing Wrought andCast Aluminum- and Magnesium-Alloy Products (Metric)B 618 Specification for Aluminum-Alloy Investment Cast-ingsB 686 Specification for Aluminum Alloy Castings, High-StrengthB 881 Terminology Relating to Aluminum- andMagnesium-Alloy ProductsB 918 Pra

9、ctice for Heat Treatment of Wrought AluminumAlloysG110 Practice for Evaluating Intergranular Corrosion Re-sistance of Heat TreatableAluminumAlloys by Immersionin Sodium Chloride + Hydrogen Peroxide Solution2.3 ANSI Standard:H35.1 Alloy and Temper Designation Systems for Alumi-num42.4 SAE Standard:AM

10、S 2771 Heat Treatment of Aluminum Alloy Castings3. Terminology3.1 Definitions:3.1.1 Refer to Terminology B 881 for terminology relatingto the heat treatment of castings.4. Equipment4.1 Heating MediaAluminum castings are typically heattreated in air chamber furnaces; however, lead baths, oil baths,fl

11、uidized beds, or even superheated steam may be used inspecific applications. The use of uncontrolled heating is notpermitted. Whichever heating means are employed, carefulevaluation is required to ensure that the casting respondsproperly to heat treatment and is not overheated or damaged bythe heat

12、treatment environment. Salt baths are not recom-mended for the commercial heat treatment of aluminum1This practice is under the jurisdiction of ASTM Committee B07 on LightMetals and Alloys and is the direct responsibility of Subcommittee B07.01 onAluminum Alloy Ingots and Castings.Current edition ap

13、proved Aug. 7, 2008. Published August 2008. Originallyapproved in 2001. Last previous edition approved in 2007 as B 917/B 917M 2007.2Available from Society of Automotive Engineers (SAE), 400 CommonwealthDr., Warrendale, PA 15096-0001, http:/www.sae.org.3For referenced ASTM standards, visit the ASTM

14、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.4Available from Aluminum Association, Inc., 1525 Wilson Blvd., Suite 600,Arlington, VA 22209, http:/www.alum

15、inum.org.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 19428-2959, United States.castings in volume. (WarningNitrate baths must not be usedin the heat treatment of 5xx.0 series castings becau

16、se of theinherent explosion hazard.4.2 Air Chamber Furnacesmay be oil or gas-fired or maybe electrically heated. The atmosphere in air chamber furnacesmust be controlled to prevent porosity resulting from solutionheat treatment. Furnace components that are significantlyhotter than the metal should b

17、e suitably shielded for sectionthicknesses of less than 0.250 in. 6 mm to prevent adverseradiation effects. The atmosphere in air chamber furnaces mustbe controlled to prevent porosity resulting from solution heattreatment (see Note 1). The suitability of the atmosphere in anair-chamber furnace can

18、be demonstrated by testing, in accor-dance with 8.4.3.1, that products processed in that furnace aresubstantially free of heat treat induced porosity.NOTE 1Heat treat induced porosity may lower mechanical propertiesand commonly causes blistering of the surface of the material. Thecondition is most l

19、ikely to occur in furnaces in which the products ofcombustion contact the work, particularly if the gases are high in watervapor or contain compounds of sulfur. Surface discoloration is a normalresult of solution heat treatment of aluminum alloys and should not beinterpreted as evidence of damage fr

20、om overheating or as heat treatinduced porosity.4.3 Automatic Recording and Control Equipmentto con-trol temperature of air furnaces shall be capable of maintainingtemperature in the working zone to within 610F 65C ofthe specified temperature.4.4 Quench BathsQuenching is normally performed byimmersi

21、on of castings in a hot-water bath as described inTables 1-4. The water baths must be located close enough tosolution heat-treating facilities to minimize delay in quenching.Tanks must be of adequate size for the expected work load andmust have the means of providing adequate circulation of thequenc

22、hing media about the work load. Means for heating orcooling the quench water should be available when needed.NOTE 2Quenching may be performed by alternative means such astotal immersion in a glycol and water solution, a liquefied gas, cold water,hot water, or boiling water, or by air blast or fog to

23、 minimize distortionprovided samples from the material, so quenched, will conform to the (1)mechanical properties, (2) other requirements of the applicable castingspecification and (3) not exhibit more intergranular corrosion susceptibil-ity than if the metal was immersion quenched in cold water. Th

24、e use ofwater sprays or high-velocity high-volume jets of water in which thematerial is thoroughly and effectively flushed is satisfactory for quench-ing. Alternative quench media are frequently contingent on the particularalloy and the end use of the casting.5. Furnace Temperature Uniformity and Ca

25、librationRequirements5.1 Calibration of Equipment:5.1.1 Thermocouple wire and sensors shall be calibratedagainst wire or sensors whose calibration is traceable to NIST).Thermocouples made from calibrated wire rolls may be used inlieu of individually calibrated thermocouples in which case, theroll ca

26、libration shall be that of the average of samples takenfrom both ends of the roll. The roll shall not be used if thedifference in the highest and lowest reading exceeds 2F 1C.5.1.2 Working instruments shall be calibrated at least onceevery three months against a test instrument that is traceable toN

27、IST. Accuracy shall be 6 0.3 % of range.5.2 Furnace Temperature Survey:5.2.1 A temperature survey, to ensure compliance with theapplicable recommendations presented herein, shall be per-formed for each furnace.5.2.2 A new temperature survey shall be made after anymodification, repair, adjustment (fo

28、r example, to power con-trols, or baffles), or rebuild which may have altered thetemperature uniformity characteristics of the furnace andreduced the effectiveness of the heat treatment.5.3 Batch Furnace Surveys:5.3.1 The initial temperature survey shall be made at themaximum and minimum temperature

29、 of solution heat treat-ments and precipitation heat treatments for which each furnaceis to be used. There shall be at least one test location for each25 ft30.70 m3 of air furnace volume up to a maximum of 40test locations, with a minimum of nine test locations, one ineach corner and one in the cent

30、er.5.3.2 After the initial survey, each furnace shall be surveyedmonthly, except as provided in 5.3.7. The monthly survey shallbe at one operating temperature for solution heat treatment andone for precipitation heat treatment.5.3.3 There shall be at least one test location for each 40 ft31 m3 of lo

31、ad volume, with a minimum of nine test locations,one in each corner and one in the center.5.3.4 The surveys shall reflect the normal operating charac-teristics of the furnace. If the furnace is normally charged afterbeing stabilized at the correct operating temperature, thetemperature-sensing elemen

32、ts shall be similarly charged. If thefurnace is normally charged cold, the temperature-sensingelements shall be charged cold. After insertion of thetemperature-sensing elements, readings should be taken fre-quently enough to determine when the temperature of thehottest region of the furnace approach

33、es the bottom of thetemperature range being surveyed. From that time until thermalequilibrium is reached, the temperature of all test locationsshould be determined at 2-min intervals in order to detect anyover-shooting. After thermal equilibrium is reached, readingsshould be taken at 5-min intervals

34、 for sufficient time todetermine the recurrent temperature pattern, but for not lessthan 30 min. Before thermal equilibrium is reached, none of thetemperature readings should exceed the maximum temperatureof the range being surveyed. After thermal equilibrium isreached, the maximum temperature varia

35、tion of all elements(both load and furnace thermocouples) shall not exceed 20F10C and shall not vary outside the range being surveyed.5.3.5 For furnaces of 10 ft30.25 m3 or less the temperaturesurvey may be made with a minimum of three thermocoupleslocated at front, center, and rear or at top, cente

36、r, and bottom ofthe furnace.5.3.6 For furnaces used only for precipitation treatment,after the initial temperature-uniformity survey, as outlined in5.3.7, surveys need not be made more often than at each6-month interval provided that (1) test specimens from each lotare tested and meet applicable mat

37、erial specifications require-ments, (2) the furnace is equipped with a multipoint recorder,or (3) one or more separate load thermocouples are employedto measure and record actual metal temperatures.B 917/B 917M 0825.3.7 Monthly surveys for batch furnaces are not necessarywhen the furnace or bath is

38、equipped with a permanentmultipoint recording system with at least two sensing thermo-couples in each zone or when one or more separate loadthermocouples are employed to measure actual metal tempera-ture, providing that uniformity surveys show a history ofsatisfactory performance for a period of at

39、least 6 months. Thesensing thermocouples shall be installed so as to record thetemperature of the heated media (air, lead, and so forth) oractual metal temperatures. However, periodic surveys shallalso be made at 6-month intervals in accordance with theprocedures outlined for the monthly survey.5.4

40、Continuous Furnace Surveys:5.4.1 For continuous heat-treating furnaces, the type ofsurvey and the procedures for performing the survey should beestablished for each particular furnace involved. The types ofcontinuous heat-treating furnaces may vary considerably, de-pending upon the product and sizes

41、 involved. For some typesand sizes of furnaces, the only practical way to survey thefurnace is to perform an extensive mechanical property surveyof the limiting product sizes to verify conformance with thespecified mechanical properties for such items. When the typeand size of the furnace makes this

42、 practical, monthly surveysshould be made, using a minimum of two load thermocouplesattached to the material. The surveys should reflect the normaloperating characteristics of the furnace. The results of thesesurveys shall indicate that the metal temperature never exceedsthe allowable maximum metal

43、temperature specified for solu-tion heat treatment (Tables 1-4 as appropriate) after all loadthermocouples have reached the minimum metal temperaturespecified.5.4.2 Furnace control temperature-measuring instrumentsshall not be used to read the temperature of the test temperaturesensing elements.5.5

44、Monitoring of QuenchA monitoring plan shall bedeveloped and utilized for all modes of quenching for allproducts covered by this practice. The plan should incorporateconductivity or hardness checking, or both, to determine theuniformity of the quench. Areas having substantially higherconductivity or

45、lower hardness than other areas of similarthickness in the lot shall be investigated to ensure that therequirements of the material specification are met.5.6 Temperature-Measuring System CheckThe accuracyof the temperature-measuring system shall be checked underoperating conditions weekly. Check sho

46、uld be made by insert-ing a calibrated test temperature-sensing element adjacent tothe furnace temperature-sensing element and reading the testtemperature-sensing element with a calibrated test potentiom-eter. When the furnace is equipped with dual potentiometermeasuring systems which are checked da

47、ily against each other,the above checks may be conducted every 3 months rather thanevery week. The test temperature-sensing element, potentiom-eter, and cold junction compensation combination shall havebeen calibrated against NIST primary or secondary certifiedtemperature-sensing elements, within th

48、e previous 3 months, toan accuracy of 62F 61C.5.6.1 If the difference between the two readings in 5.6exceeds 610F 66C, the cause of the difference shall bedetermined and corrected before commencing additional ther-mal processing. The responsible quality organization shall benotified and appropriate

49、corrective action shall be taken anddocumented including an evaluation of the possible effects ofthe deviation on castings processed since the last successfultest.TABLE 1 Recommended Heat Treatment for Sand and Investment Type Alloys (Inch-Pound Units)AlloyAFinal TemperASolution Heat TreatmentB,CPrecipitation Heat TreatmentDMetal Temperature,610FTime atTemperature, hMetal Temperature,610FTime atTemperature, h201.0 T6 960then 9802E14 to 20room temperaturethen 31012 to 2420T7 960then 9802E14 to 20room temperaturethen 37012 to 245A201.0 T7 955