1、Designation: A 991/A 991M 08Standard Test Method forConducting Temperature Uniformity Surveys of FurnacesUsed to Heat Treat Steel Products1This standard is issued under the fixed designation A 991/A 991M; the number immediately following the designation indicates the yearof original adoption or, in
2、the case of revision, the year 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.1. Scope*1.1 This test method covers the procedures used to conducta temperature uniformity surv
3、ey on a furnace used to heat treatsteel products. This method is used to determine the capabilityof the furnace to meet the permissible temperature variationspecified in the applicable product specification, or as agreed toby the purchaser and supplier of heat treat services. Surveydocumentation req
4、uirements, and the procedure used to subse-quently establish the furnace working zone, are defined in thistest method.1.2 This test method covers heat treat furnaces in any of thefollowing categories:1.2.1 Continuous or semi-continuous conveyance furnaces,1.2.2 Batch furnaces, and1.2.3 Salt or liqui
5、d baths and fluidized beds.1.3 This test method only applies when specified in theproduct specification or the purchase order.1.4 Controlling a heat treatment of steel products usingthermocouples attached to the extremities of each load is analternative to performing a furnace survey.1.5 By mutual a
6、greement between the purchaser and thesupplier of heat treat services, more stringent and/or additionalrequirements may be specified. The acceptance of any suchadditional requirements shall be dependent on negotiationswith the supplier and must be included in the order as agreedupon by the purchaser
7、 and supplier.1.6 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 result in non-co
8、nformancewith the standard.1.7 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-priate safety and health practices and determine the applica-bility of regulatory limitations p
9、rior to use.2. Referenced Documents2.1 ASTM Standards:2E 207 Test Method for Thermal EMF Test of Single Ther-moelement Materials by Comparison with a ReferenceThermoelement of Similar EMF-Temperature PropertiesE 220 Test Method for Calibration of Thermocouples ByComparison TechniquesE 230 Specificat
10、ion and Temperature-Electromotive Force(EMF) Tables for Standardized ThermocouplesE 608/E 608M Specification for Mineral-Insulated, Metal-Sheathed Base Metal Thermocouples2.2 SAE Standard:3AMS 2750 Pyrometry3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 batch furnace, nheatin
11、g device in which materialmay be stationary or oscillating during the processing cycle.3.1.2 continuous conveyance furnace, nheating devicethrough which material is moved intentionally at a constantrate during the processing cycle.3.1.3 extremities, nas referring to furnace working zone;outer bounda
12、ries in all three dimensions (length, width, andheight) of the material being processed.3.1.4 operating range, nexpected range of temperatureover which a furnace will be controlled to heat treat steelproducts.1This test method is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel
13、and Related Alloys and is the direct responsibility of SubcommitteeA01.13 on Mechanical and Chemical Testing and Processing Methods of SteelProducts and Processes.Current edition approved Oct. 1, 2008. Published October 2008. Originallyapproved in 1998. Last previous edition approved in 2004 as A 99
14、1/A 991M 98(2004).2For 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.3Available from Society of Automotive Engin
15、eers (SAE), 400 CommonwealthDr., Warrendale, PA 15096-0001, http:/www.sae.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.3.1.5 primary survey, ninitial evaluation
16、 of the furnace,or an evaluation triggered by the initiation of a major furnacemodification.3.1.6 secondary survey, nevaluation of the furnace trig-gered by the expiration of a time requirement.3.1.7 semi-continuous conveyance furnace, nheating de-vice through which material is moved intentionally w
17、ith apredetermined start-stop-start pattern during the processingcycle.3.1.8 working zone, nmaximum volume and location inthe furnace that meet the permissible temperature variation.4. Significance and Use4.1 Furnaces for heat treatment of steel products are used inmany industries, in many ways. Reg
18、ardless of heat treatfurnace type, or processing cycle, it may be necessary for usersto know the temperature uniformity in the furnace and whetherthe material is processed in a zone within the furnace that iscapable of meeting the applicable permissible temperaturevariation requirements.4.2 The proc
19、edures in this test method may be used by thoseusing, manufacturing, and providing calibration service for,heat treat furnaces used to process steel products.5. Furnace Survey Equipment5.1 Thermocouples:5.1.1 Metal sheathed thermocouples shall be in accordancewith Specification E 608/E 608M.5.1.2 Th
20、e use of extension wires is permitted when com-pensated connectors, plugs, jacks, and terminal strips are used.5.1.3 Thermocouples made from spool wire shall meet therequirements of AMS 2750.5.1.4 The use of spliced extension wire is prohibited.5.1.5 Thermocouples may be reused if the requirements o
21、fAMS 2750 (except Paragraphs 3.1.1.10 and 3.1.1.11 of Rev. D)are met.5.2 Calibration:5.2.1 All reference, primary, secondary, test and workingequipment, instrumentation and sensors used in conjunctionwith this test method shall meet the requirements of calibrationdefined by Test Methods E 207 and E
22、220.5.2.2 Temperature measuring devices shall be calibratedwithin three months prior to use.5.2.3 Calibration shall be traceable to the National Instituteof Standards Technology standards, or equivalent nationalstandards. Calibration to such national standards shall be doneat least once every two ye
23、ars.5.2.4 Calibration shall be within the temperature range to beused in the survey and at intervals not greater than 200F100C for primary and secondary standards.5.2.5 Correction factors, limits of error, and deviations shallbe in accordance with Specification E 230.6. Requirements6.1 Uniformity Su
24、rvey Test Conditions:6.1.1 The furnace to be surveyed shall be capable of beingtested at set point temperature(s) typical for the normaloperating range.6.1.1.1 If the operating range does not exceed a spread of300F 150C, the midpoint temperature shall be selected forthe survey.6.1.1.2 If the operati
25、ng range exceeds a spread of 300F150C, survey at the minimum and maximum set pointtemperature for the normal operating range, except that themaximum temperature need not be higher than 2000F1100C.6.1.2 Either typical or maximum production size and weightfurnace loads shall be utilized during the sur
26、vey. Use ofrepresentative material to simulate product during survey ispermitted.6.1.3 The furnace atmosphere and operating conditionsshall be representative of those used in production.6.2 Frequency of Uniformity Surveys:6.2.1 Primary Surveys:6.2.1.1 A primary survey shall have been performed withi
27、ntwelve months prior to, or run concurrently with, the firstproduction heat treatment to which this test method applies.6.2.1.2 A primary survey shall have been conducted when amajor furnace modification is completed. A major furnacemodification includes, but is not limited to, the installation ofth
28、e following: a different burner type, a new heating elementdesign, a different type of insulation system, and, a differenttype of temperature controlling device.6.2.1.3 Replacement of worn parts with similar parts orpatching of insulation that does not change the furnacecharacteristics does not cons
29、titute a major furnace modifica-tion.6.2.1.4 The survey shall be conducted within twelve monthsprior to, or run concurrently with, the first production heattreatment performed after the modification.6.2.2 Secondary Surveys:6.2.2.1 To maintain conformance with this test method, asecondary survey shal
30、l be conducted within twelve monthsafter the primary survey.6.2.2.2 Secondary surveys shall be conducted at a typicalfurnace set point temperature within the normal operatingrange. All other conditions described in 6.1 shall apply.7. Procedure7.1 Survey measuring equipment shall meet the require-men
31、ts of Section 5.7.2 Test conditions and test frequency shall be as defined in6.1 and 6.2, respectively.7.3 Place thermocouples to monitor time and temperatureprofiles in the furnace to evaluate the uniformity of theintended working zone. Place them at the outer extremities, thecenter of the proposed
32、 working zone, and in areas of suspectedvariability in the proposed working zone. Attach survey testsensors to, or set them in the load.7.4 For proposed working zones less than 12 in. 300 mmin height, it is acceptable to monitor the center height location,it is not necessary to monitor both the top
33、and bottom of theheating chamber. For proposed working zones greater than, orequal to, 12 in. 300 mm in height, both top and bottomextremities must be monitored.7.5 Continuous Conveyance and Semi-Continuous Convey-ance Furnaces:A 991/A 991M 0827.5.1 Convey test sensors through the furnace. The rate
34、ofconveyance shall be representative of normal operating condi-tions.7.5.2 The frequency of temperature recordings shall becapable of detecting variations from the test temperature rangeduring the entire conveyance through the furnace.7.5.3 Several conveyances with the test sensors attached tothe st
35、eel product, under the same conditions, may be made toensure that any recurrent temperature profiles are determined atall test locations throughout the furnace.7.5.4 Alternative surveying techniques are described in 7.7.7.6 Batch and Batch Liquid Media Furnaces:7.6.1 Take readings starting when the
36、control instrumentrises to within 200F 100C of the set point temperature andcontinue throughout the hold cycle at the set point temperature.7.6.2 Take readings at a minimum frequency of 1/10 thenormal hold time.7.6.3 Take the readings frequently enough to detect varia-tions from the test temperature
37、 range and to determine theextremes of the recurrent temperature profile, if any.7.6.4 Alternative surveying techniques are described in 7.7.7.7 Alternative Surveying TechniquesWhen agreed to bythe purchaser and the supplier of heat treat services, alternativesurveying techniques may be used to char
38、acterize the tempera-ture uniformity of the furnace and subsequently define the sizeand location of the working zone. Examples of these surveyingtechniques are listed below.7.7.1 Statistical Sampling:7.7.1.1 When it is impossible or impractical to perform thetests outlined in 7.5 and 7.6, it is perm
39、issible to substitute ananalysis of the resultant mechanical properties of the steelproducts heat treated in the subject furnace to validate tem-perature uniformity. Details of this procedure shall be as agreedto between purchaser and supplier.7.7.2 Sequential Load Sensors:7.7.2.1 This procedure may
40、 be used as an alternative tothose described in 7.5 and 7.6. It provides validation oftemperature uniformity by a series of tests rather than a singletest. In each test, determine the temperature variation pattern atone or more of the test locations.7.7.2.2 The frequency of test shall be six months.
41、7.7.2.3 The temperature shall be within the normal operat-ing range, with the narrowest permissible variation for thematerial applied to the survey.7.7.2.4 Run the furnace with a load similar to that used in anormal production cycle.7.7.2.5 Load or test sensors shall be arranged in, or incontact wit
42、h, the test load.7.7.2.6 Control setting(s) shall be identical to those used innormal production.7.7.2.7 Take readings starting when the control instrumentsrises to within 200F 100C of the set point temperature andcontinued throughout the hold cycle at the set point tempera-ture.7.7.2.8 Record the t
43、emperature of all load test and workingsensors frequently enough to detect when the specified oper-ating range is exceeded, and at least five cycles of any recurrentpattern have been observed.7.7.2.9 If no recurrent temperature profile is detected, takereadings at intervals of five minutes or less,
44、for at least 30 minafter thermal equilibrium is reached.8. Documentation of Survey Results8.1 Organizations performing surveys in accordance withthis test method shall keep pertinent documentation of theconditions and procedures used in the completion of the surveyon file for a minimum of five years
45、.8.2 Pertinent documentation shall include, but not be lim-ited to, the following:8.2.1 Specific identification of furnace surveyed,8.2.2 Date of the uniformity survey,8.2.3 Identification of the heat treat procedure,8.2.3.1 Set point temperatures,8.2.3.2 Type of atmosphere,8.2.3.3 Conveyance speed
46、(when applicable),8.2.4 Size and weight of steel product loaded in furnace attime of survey,8.2.5 Item identification numbers (lot, heat serial, etc.),8.2.6 Time and temperature data, including original tem-perature charts or original manually recorded data,8.2.7 Dimensions and location of the worki
47、ng zone(s),8.2.8 Number and location of the survey thermocouples,8.2.9 Largest observed temperature variation from the setpoints during the hold cycle,8.2.10 The time interval of the test, including the totalelapsed time. Starting time and chart speed shall be marked onthe original temperature chart
48、s,8.2.11 All pertinent equipment calibration information,8.2.12 Deviations from the test method including, but notlimited to, thermocouple failure, malfunction, or disconnec-tion.8.2.13 Name of personnel conducting the survey, and8.3 All data may be electronically recorded.9. Interpretation of Resul
49、ts and Establishment of theWorking Zone9.1 The results of the primary survey describe the tempera-ture uniformity of a furnace under a specific set of operatingconditions. Results of the application of this test method shallbe expressed as a variation from a temperature set point.9.2 Establishment of the furnace working zone is made bycomparing the temperature variation required by the productspecification, or agreed to by purchaser and supplier of heattreat services, with the variation from the temperature set pointas determined by this uniform
