1、Designation: B 851 04Standard Specification forAutomated Controlled Shot Peening of Metallic ArticlesPrior to Nickel, Autocatalytic Nickel, or Chromium Plating,or as Final Finish1This standard is issued under the fixed designation B 851; the number immediately following the designation indicates the
2、 year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers the requirements for aut
3、o-mated, controlled shot peening of metallic articles prior toelectrolytic or autocatalytic deposition of nickel or chromium,or as a final finish, using shot made of cast steel, conditionedcut wire, or ceramic media. The process is applicable to thosematerials on which test work has shown it to be b
4、eneficialwithin given intensity ranges. It is not suitable for brittlematerials. Hand peening and rotary flap peening are excludedspecifically.1.2 Shot peening induces residual compressive stresses inthe surface and near-surface layers of metallic articles, control-ling or limiting the reduction in
5、fatigue properties that occursfrom nickel or chromium plating of the article, or the fatigueproperties of unplated articles.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 appr
6、o-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 183 Practice for Preparation of Low-Carbon Steel forElectroplatingB 242 Guide for Preparation of High-Carbon Steel ForElectroplatingB 320 Practice
7、 for Preparation of Iron Castings for Electro-platingB 322 Practice for Cleaning Metals Prior to ElectroplatingB 607 Specification for Autocatalytic Nickel Boron Coat-ings for Engineering UseB 650 Specification for Electrodeposited Engineering Chro-mium Coatings on Ferrous SubstratesB 656 Guide for
8、Autocatalytic (Electroless) Nickel-Phosphorus Deposition on Metals for Engineering Use3B 689 Specification for Electroplated Engineering NickelCoatingsB 733 Specification for Autocatalytic (Electroless) Nickel-Phosphorus Coatings on MetalE 11 Specification for Wire Cloth and Sieves for TestingPurpos
9、esE 165 Test Method for Liquid Penetrant ExaminationE 709 Guide for Magnetic Particle Examination2.2 Federal Standards:4QQ-N-290 Nickel Plating (Electrodeposited)QQ-C-320 Chromium Plating (Electrodeposited)2.3 Military Standards:4MIL-S-851 Steel Grit, Shot, and Cut Wire Shot, and IronGrit and Shot B
10、last Cleaning and PeeningMIL-S-13165 Shot Peening of Metal PartsMIL-C-26074 Coating, Electroless NickelMIL-STD-45662 Calibration System Requirements2.4 SAE Standards:5SAE J441 Cut Steel Wire ShotSAE J442 Test Strip, Holder and Gage for Shot PeeningSEA J827 Cast Steel ShotSAE J1830 Size, Classificati
11、on and Characteristics of Ce-ramic Shot for Peening3. Terminology3.1 Definitions:3.1.1 Almen stripUNS G10700 carbon steel specimensthat are used to calibrate the energy of a shot peening stream(see Fig. 1).3.1.2 Almen strip holding fixturea fixture for holdingAlmen strips in suitable locations that
12、represent the positionand angular orientation of the surfaces of a part where intensityis to be determined and verified (see Fig. 2).1This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.02 on Pre Tre
13、atment.Current edition approved April 1, 2004. Published April 2004. Originallyapproved in 1994. Discontinued January 2004 and reinstated in 2004 as B 85104.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of AS
14、TMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.4Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.5Available from Society of Automotive Engineers, 400 Commonwea
15、lth Drive,Warrendale, PA 15096.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.3 arc heightflat Almen strips, when subjected to astream of shot moving at an adequate velocity, bending in anarc corresponding to the amount of energ
16、y transmitted by theshot stream. The height of the curved arc measured inmillimeters is the arc height, measured by an Almen gage (seeFig. 3).3.1.4 automatic equipmentshot peening equipment inwhich parts, fixtures, nozzles, and peening parameters arepreset by hand or by locating fixtures and verifie
17、d by inspectionpersonnel. The peening time is monitored automatically, andthe air pressure or wheel speed is set manually.3.1.5 compressive stressescold working or stretching thesurface beyond the elastic limit by shot peening, creating alayer in compression below the surface. The depth of compres-s
18、ive stresses is measured by the crown of the dimple to thedepth.3.1.6 coveragethe extent of obliteration of the originalsurface by dimples produced by impact from individual shotparticles and expressed as a percentage. See Note 1.3.1.7 depth of compressive stresseswhere the stress pro-file passes th
19、rough 0 stress.3.1.8 intensitythe Almen strip arc height at saturation. Archeight is not termed intensity correctly unless saturation isachieved.3.1.9 liquid tracer systema liquid coating material bear-ing a pigment that fluoresces under an ultraviolet light andremoves at a rate proportioned to peen
20、ing coverage.3.1.10 microprocessor-controlled equipmentpeeningequipment that has nozzle holding fixtures and is computercontrolled for processing, monitoring, and documentation ofthe peening parameters critical to process certification.3.1.11 nozzle holding fixturea fixture that holds thenozzles at
21、the required location, distance, and angle in a lockedposition during the peening operation.3.1.12 process interrupt parametersfor critical peeningoperations, parameters such as shot flow, air pressure, partr/min, oscillation rate, and cycle time that must be monitoredwithin process requirements.3.1
22、.13 saturationthe minimum duration of peening nec-essary to achieve the desired Almen intensity which, whendoubled, does not increase the Almen strip arc height by morethan 10 %.FIG. 1 Almen Test SpecimenFIG. 2 Assembled Test Strip and HolderFIG. 3 Almen GageB8510423.1.14 saturation curvea curve tha
23、t plots peening time onthe Almen strip (abscissa) versus Almen strip arc height(ordinate) achieved for the peening time (see Fig. 4).3.1.15 surface obliterationthe condition of a peened sur-face in which 100 % of the surface has been dimpled with shotimpressions.NOTE 1A 100 % coverage is defined as
24、that leaving unpeened 2 % orless of the original surface because the estimation of coverage of theimpressions is difficult when this is approximately 98 % of the totalsurface. The 100 % coverage is a theoretical limiting value. Hence, theterm complete coverage is preferred. Complete coverage usually
25、 requiresincreasing the base time, that is, the time of peening to reach 98 %coverage, by 15 to 20 %. Values of 200 %, 300 %, etc. are obtained bymultiplying this run time by 2, 3, etc.4. Ordering Information4.1 When ordering articles to be shot peened, the purchasershall state the following:4.2 AST
26、M designation.4.3 Type, size, and hardness of shot to be used (see 6.1).4.4 Number and frequency of the determinations of shotsize and uniformity required, if other than those specified in8.1.1.4.5 Peening intensity to be used at each location (see 8.2).4.6 Number, frequency, and locations of Almen
27、test speci-mens to be provided for intensity verification and monitoringof the process if other than those specified in 8.2, 8.2.1, and8.2.2.4.7 Areas on the part that are to be shot peened and those tobe protected from the peening (see 7.5).4.8 Whether magnetic particle or penetrant inspection isre
28、quired before peening (see 7.2).4.9 Amount (percent) of coverage required in the areas to bepeened. A complete coverage is the minimum requirement (see3.1.6 and 8.3).4.10 Method for measuring coverage (see 8.3.1).4.11 Type of equipment to be used, automated or computer-monitored microprocessor (see
29、6.3 and X1.10-X1.12).4.12 Details of any post treatment such as corrosion protec-tion (see 9.5).4.13 Requirements of certification and test records, asspecified in Section 10.5. Significance and Use5.1 Shot peening is a process for cold working surfaces bybombarding the product with shot of a solid
30、and sphericalnature propelled at a relatively high velocity. In general, shotpeening will increase the fatigue life of a product that is subjectto bending or torsional stress. It will improve resistance tostress corrosion cracking. It can be used to form parts or correcttheir shapes. See Appendix X1
31、 for additional information.5.2 It is essential that the shot peening process parametersbe controlled rigidly to ensure repeatability from part to partand lot to lot.5.3 This specification covers techniques and methods nec-essary for proper control of the shot peening process.6. Materials and Equipm
32、ent6.1 Shot Material Composition:6.1.1 Cast SteelCast steel shot shall conform to therequirements of SAE J827.6.1.2 Cut WireCut wire shot shall be made from coldfinished, round wire, confirming to SAE J441.6.1.3 Ceramic ShotCeramic beads shall conform to thechemical composition given in Table 1 and
33、to SAE J1830.6.1.4 Shot Form and Shape:6.1.4.1 Cast SteelCast steel shot shall be spherical inshape and free of sharp edges, corners, and broken pieces. Itshall conform to the acceptable shapes given in Fig. 5. Thenumber of nonconforming shapes (see Fig. 6) shall not exceedthe values given in Table
34、2.6.1.4.2 Cut WireCut wire shot shall be spherical in shape.It shall be free of sharp edges, corners, and broken pieces. Thenumber of nonconforming shapes shall not exceed the valuesgiven in Table 2.6.1.4.3 Ceramic ShotCeramic shot shall be spherical inshape and free of sharp edges, corners, and bro
35、ken pieces. Thenumber of nonconforming shapes shall not exceed the valuesgiven in Table 2.6.1.5 HardnessThe hardness of the media shall exceedthat of the material to be processed.6.1.5.1 Cast SteelCast steel shot shall have a hardness ofHRc45 to HRc55. Special hard cast steel shot shall be used onpr
36、oducts harder than HRc50 and shall have a hardness of HRc55 to HRc65.6.1.5.2 Cut WireCut wire shot shall have a hardness equalto or greater than that given in Table 3.6.1.5.3 Ceramic ShotCeramic shot shall have a minimumhardness of 560 HV30(30 kgf).6.1.6 Size:(1) The size of the media shall be capab
37、le of producing therequired intensity in the required time.(2) If a peened surface contains a fillet, the nominal size ofthe shot shall not exceed one-half of the radius of the fillet.(3) If the shot must pass through an opening, such as a slot,to reach a peened surface the nominal diameter of the s
38、hot shallnot exceed one-fourth of the width or the diameter of theopening.6.1.6.1 Cast SteelCast steel shot charged into a machineshall conform to the screen requirements given in Table 4 forFIG. 4 Saturation CurveTABLE 1 Composition of Ceramic ShotZrO2, % SiO2,% Al2O3,% Fe2O3, % Free Iron, %Specifi
39、cGravity,g/cm360.070.0 28.033.0 10.0 max 0.1 max 0.1 max 3.603.95B851043the nominal size selected. When a machine has a completelynew charge of cast steel shot, conditioning shall be conducted,to remove the oxide layers on the shots, by bombarding onto ahardened steel surface for a minimum of two pa
40、sses. Condi-tioning may not be required if the addition to the chargealready in the machine is below 25 %. If the addition of over25 % is made to the charge, conditioning is required.6.1.6.2 Cut WireThe diameter of cut wire shot chargedinto a machine shall conform to the requirements given inTable 4
41、. Cut wire shot shall conform to the requirements oflength and cumulative weight given in Table 5. It is mandatorythat only preconditioned cut wire shot be used.6.1.6.3 Ceramic ShotCeramic shot charged into the peen-ing machine shall conform to the screen requirements of Table6.6.2 Almen Strips, Blo
42、cks, and Gages Almen strips,blocks, and gages used shall meet the requirements of SAEJ442.6.3 EquipmentShot peening shall be conducted in a ma-chine that is designed for the purpose, propels shot at highspeed against the product, moves the product through the shotstream in a way that ensures complet
43、e and uniform peening,and screens the shot continuously to remove broken or defec-tive shot.7. Pre-Peening Treatment7.1 Prior OperationsAreas of parts to be shot peenedshall be within dimensional requirements before peening.Except as otherwise permitted, all heat treatment, machining,and grinding sh
44、all be completed before shot peening. All filetsshall be formed, all burrs removed, and all sharp edges andcorners that require peening provided with sufficient radii priorto peening, in order to result in complete coverage without anydistortion, chipping, or rollover.7.2 Flaw and Crack TestingWhen
45、required, magneticparticle, penetrant, ultrasonic, or other flaw or crack detectionprocesses shall be completed prior to peening. See Test MethodE 165 and Guide E 709.7.3 Corrosion and DamageParts shall not be peened ifthey show evidence of invasive corrosion or mechanicaldamage on the surface.7.4 C
46、leaningCleaning prior to peening shall be accom-plished by vapor degreasing, solvent wiping, warm solventspray, or an acceptable water-base nonflammable product, asrequired, to remove all soils, scale, and coatings from thesurface areas to be peened. See Practices B 183, B 242, B 320,and B 322.7.5 M
47、askingSurfaces designated on the drawing to be freeof shot peening marks shall be masked or otherwise protectedfrom the shot stream or indirect impingement by shot.7.5.1 Suitable masking materials are adhesive tape, sheetrubber, etc. If adhesive tape is used, it shall be coated on oneface with adhes
48、ive, and when the tape is removed from thesurface it shall not show any evidence of corrosion or leave anyresidue on the surface. Areas not requiring peening and notrequired to be masked shall be considered optional.8. Procedure8.1 ShotShot charged into the peening machine shall beas specified by th
49、e purchaser and meet the requirements of 6.1for the particular type, size, and material required. Unlessotherwise specified, all shot shall be maintained in the machineso that it conforms to the requirements of Table 7.8.1.1 Uniformity DeterminationAt least one determina-tion for shot size and uniformity in accordance with Table 7shall be made before and after each production run and aftereach8hofproduction on long runs, when using cast or cutFIG. 5 Acceptable ShapesFIG. 6 Unacceptable ShapesTABLE 2 Maximum Allowable Nonconforming ShapesCastSt
