1、Designation: A 604/A 604M 07Standard Practice forMacroetch Testing of Consumable Electrode Remelted SteelBars and Billets1This standard is issued under the fixed designation A 604/A 604M; the number immediately following the designation indicates the yearof original adoption or, in the case of revis
2、ion, 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 practice2cove
3、rs testing and inspection and isapplicable to bars, billets, and blooms of carbon, alloy, andstainless steel which have been consumable electrode remelted.1.2 For the purpose of this practice, the consumable elec-trode remelting process is defined as a steel refining methodwherein single or multiple
4、 electrodes are remelted into acrucible producing an ingot which is superior to the originalelectrode by virtue of improved cleanliness or lower gascontent or reduced chemical or nonmetallic segregation. SeeAppendix X1 and Appendix X2 for descriptions of applicableremelting processes.1.3 This practi
5、ce and the accompanying comparison mac-rographs3are generally applicable to steel bar and billet sizesup to 225 in.21450 cm2 in transverse cross section.1.4 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 e
6、xact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of t
7、he user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:4E 381 Method of Macroetch Testing Steel Bars, Billets,Blooms, and Forgings2.2 ASTM Adjuncts:Adjunct to A 6
8、04/A 604M Practice for Macroetch Testing ofConsumable Electrode Remelted Steel Bars and Billets33. Description of Macroetch Testing3.1 This practice employs the action of an acid or othercorrosive agent to develop the characteristics of a suitablyprepared specimen. After etching, the sections are co
9、mparedvisually, or at a very low magnification, if necessary forclarification of conditions, to standard plates describing thevarious conditions which may be found. Materials react differ-ently to etching reagents because of variations in chemicalcomposition, method of manufacture, heat treatment, a
10、nd manyother variables.4. Significance and Use4.1 Macroetch testing, as described herein, is a method forexamining and rating transverse sections of bars and billets todescribe certain conditions of macro segregation which areoften characteristic of consumable electrode remelted materi-als.4.2 This
11、practice is not intended to define major defectssuch as those described by Method E 381.5. Application5.1 When material is furnished subject to macroetch testingand inspection under this practice, the manufacturer andpurchaser should be in agreement concerning the following:5.1.1 The stage of manufa
12、cture at which the test shall beconducted,5.1.2 The number and location of the sections to be tested,1This practice is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.06 on Steel Forgings and Billets.Current
13、 edition approved May 1, 2007. Published June 2007. Originallyapproved in 1970. Last previous edition approved in 2003 as A 604 93 (2003).2ASTM Committee A01 gratefully acknowledges the help of the AISI Commit-tee on General Metallurgy in preparing the appendix, assembling the macroetchphotographs,
14、and assisting with the text of this practice.3A complete set of the 20 macrographs on glossy paper available from ASTMInternational Headquarters. Order Adjunct No. ADJA0604. Original adjunct pro-duced in 1985.4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custom
15、er Service 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,
16、PA 19428-2959, United States.5.1.3 The condition and preparation of the surface to bemacroetched,5.1.4 The etching reagent, temperature and time of etching,or degree of etching including any special techniques whichmust be used, and5.1.5 The type and degree of conditions or combinationsthereof that
17、shall be considered acceptable or subject tometallurgical review.6. Sample Preparation6.1 Unless otherwise specified, the test shall be performedon specimens, usually14 to 1 in. 6 to 25 mm thick, cut toreveal a transverse surface.6.2 Disks for macroetch inspection may be removed frombillets by a var
18、iety of methods including torch cutting, sawing,machining, or high-speed abrasive wheels. Adequate prepara-tion of the surface for macroetching must completely removethe effects of torch cutting or high-speed abrasive wheels.6.3 Due to the nature of the conditions to be detected,further surface prep
19、aration is usually required.6.4 When such further preparation is performed, grinding,machining, or sanding should be carried out in such a manneras not to mask the structure.6.5 The surface of the disk to be etched must be free of dirt,grease, or other foreign material which might impair the resulto
20、f the test.7. Etching Reagents7.1 The etching response and appearance is dependent uponthe type and temperature of the etching reagent and the time ofimmersion. These details must be established by agreementbetween manufacturer and purchaser.7.2 For illustrative purposes some of the commonly usedetc
21、hing reagents are as follows:7.2.1 Hydrochloric AcidA solution of 1 part commercialconcentrated hydrochloric acid (HCl, sp gr 1.19) and 1 partwater is more generally used than any other macroetchingreagent. This solution may be heated without significantchange in concentration, and may be reused if
22、it has notbecome excessively contaminated or weakened. Etching isgenerally done with the solution at a temperature of approxi-mately 160F 70C.7.2.2 Hydrochloric Acid-Sulfuric Acid MixtureA mixturecontaining 50 % water, 38 % commercial concentrated HCl,and 12 % commercial concentrated sulfuric acid (
23、H2SO4,spgr1.84) is sometimes used in place of the previously mentioned50 % HCl solution. The statements in the previous paragraphregarding reuse and temperature of etchant are applicable tothis reagent.7.2.3 Aqua RegiaA solution consisting of 1 part concen-trated nitric acid (HNO3, sp gr 1.42) and 2
24、 parts concentratedHCl is used on corrosion and heat-resistant materials of the18 % chromium, 8 % nickel type and higher alloy types. Thisreagent is used at room temperature.NOTE 1The reagents in 7.2.1, 7.2.2, and 7.2.3 should be used underventilating hoods or with some provision to remove the corro
25、sive fumes.7.2.4 Nitric AcidThis etchant consists of 5 % HNO3solution in alcohol or water, and is generally used at roomtemperature. When this reagent is used, the etch disk must havea smooth surface.8. Etching Containers8.1 Macroetching must be done in containers that areresistant to attack from th
26、e etching reagents. Caution must beexerted to prevent the occurrence of electrolytic couples whichcan cause uneven attacks and misleading results.9. Preparation of Etched Surface and Examination9.1 Upon completion of etching, surfaces of disks should becleaned by either chemical or mechanical method
27、s that do notaffect the macroetch quality. Care should be taken to preventrusting of the etched surface.10. Interpretation of Conditions Found by Macroetching10.1 Four distinct classes of conditions are defined anddescribed under this practice:10.1.1 Class 1: FrecklesCircular or near-circular darket
28、ching areas generally enriched with carbides and carbide-forming elements.10.1.2 Class 2: White SpotsLight etching areas, having nodefinitive configuration or orientation which are generallyreduced in carbide or carbide-forming elements.10.1.3 Class 3: Radial SegregationRadially or spirallyoriented
29、dark etching elongated areas occurring most fre-quently at mid-radius which are generally carbide enriched.This condition may be easily confused with freckles in somematerials.10.1.4 Class 4: Ring PatternOne or more concentric ringsevidenced by a differential in etch texture associated withminor com
30、position gradients and ingot solidification.10.2 Macroetch photographs show examples of each of theconditions revealed by macroetch testing, with five degrees ofseverity, identified as A, B, C, D, and E for each condition.Degree A exhibits the minimum occurrence of each conditiondetectable by visual
31、 examination of the etched surface, whiledegrees B, C, D, and E represent increasing severity ofoccurrence.10.3 For each condition, or combination of conditions,ratings shall be obtained by comparing each macroetchedsection with the standard photographs. Bar or billet sections to225 in.21450 cm2 cro
32、ss-sectional area may be rated againstthese standards. Larger sizes may be rated by agreementbetween manufacturer and purchaser, but caution must beexercised in interpretation of such results. Figs. 1-20 have beenreduced 44 % in area from the standard photographs.10.4 If the appearance of a given co
33、ndition does not exactlymatch one of the five standard photographs, it shall be assignedthe rating of the standard that it most nearly matches.10.5 No standards for acceptance are stated or implied inthese illustrations. The extent to which each condition may bepermissible varies with the intended a
34、pplication, and suchstandards should be stated in the applicable product specifica-tion, or may be the subject of negotiation between manufac-turer and purchaser.A 604/A 604M 07211. Keywords11.1 consumable electrode remelting; electroslag remelting;freckles; macro etching; radial segregation; ring p
35、attern; seg-regation; vacuum arc remelting; white spotsFIG. 1 Class 1FrecklesSeverity AFIG. 2 Class 1FrecklesSeverity BA 604/A 604M 073FIG. 3 Class 1FrecklesSeverity CFIG. 4 Class 1FrecklesSeverity DA 604/A 604M 074FIG. 5 Class 1FrecklesSeverity EFIG. 6 Class 2White SpotsSeverity AA 604/A 604M 075FI
36、G. 7 Class 2White SpotsSeverity BFIG. 8 Class 2White SpotsSeverity CA 604/A 604M 076FIG. 9 Class 2White SpotsSeverity DFIG. 10 Class 2White SpotsSeverity EA 604/A 604M 077FIG. 11 Class 3Radial SegregationSeverity AFIG. 12 Class 3Radial SegregationSeverity BA 604/A 604M 078FIG. 13 Class 3Radial Segre
37、gationSeverity CFIG. 14 Class 3Radial SegregationSeverity DA 604/A 604M 079FIG. 15 Class 3Radial SegregationSeverity EFIG. 16 Class 4Ring PatternSeverity AA 604/A 604M 0710FIG. 17 Class 4Ring PatternSeverity BFIG. 18 Class 4Ring PatternSeverity CA 604/A 604M 0711FIG. 19 Class 4Ring PatternSeverity D
38、FIG. 20 Class 4Ring PatternSeverity EA 604/A 604M 0712APPENDIXES(Nonmandatory Information)X1. CONSUMABLE ELECTRODE VACUUM MELTINGX1.1 Process DescriptionX1.1.1 Consumable electrode vacuum melting (CEVM) ofsteel has grown from a laboratory process to a major produc-tion operation capable of producing
39、 ingots in certain grades upto 60 in. 1500 mm in diameter, weighing 50 tons 45 t. Theavailable ingot sizes and weights vary from grade to grade,depending upon their complexity and alloy content. Currently,a significant proportion of the ultra-high-strength steels foraircraft and missiles, bearing st
40、eels for aircraft engines, andother speciality alloys are being consumable electrode vacuummelted.X1.1.2 The consumable electrode vacuum melting processis diagramed in Fig. X1.1. To start the melting operation, anelectrode produced from conventional air-melted or vacuum-processed steel is suspended
41、in the consumable electrodevacuum melting furnace. The system is evacuated and an arc isstruck to a bottom starting pad. Molten metal is transferredacross the arc from the electrode to the solidifying ingotcontained within the water-cooled copper crucible. As meltingproceeds and the ingot solidifies
42、 progressively upward, theelectrode is fed downward to maintain the proper arc length.Asthe metal droplets pass through the arc, they are exposed to thisvacuum at extremely high arc temperatures, producing exten-sive degassification, as well as some breakdown and dispersionof inclusions. Due to the
43、rapid cooling provided by the coppercrucible, only a portion of the ingot is molten at a time andsolidification proceeds in a continuously progressive manner.X1.2 Product CharacteristicsX1.2.1 Essentially, the CEVM operation changes the prop-erties of steel in three ways:X1.2.1.1 By reducing gas con
44、tent.X1.2.1.2 By improving microcleanliness. The nonmetallicinclusion content is rated in a manner similar to that used forair melt except that the level is generally lower and a differentchart is used.X1.2.1.3 By changing the mode of solidification from thatof the traditional static-cast ingot to a
45、 progressive solidificationprocess, involving high heat input from an arc and rapid heatextraction by the water-cooled copper crucible.X1.2.2 Depending upon the grade of steel and the applica-tion under consideration, consumable electrode vacuum melt-ing is reported to significantly improve one or m
46、ore of thefollowing properties: transverse ductility in aircraft forgingbillets, fatigue strength or endurance limit, notched tensilestrength or fracture toughness, Charpy V-notch impactstrength, stress rupture, and creep strength. Furthermore, hotworkability and yield of some grades are significant
47、ly im-proved. The CEVM process has also made possible thedevelopment of new alloys for extremely high-strength orFIG. X1.1 Consumable Electrode Vacuum Melting FurnaceA 604/A 604M 0713high-temperature applications that did not exhibit satisfactoryproperties when melted by other methods.X1.3 Macrotech
48、 CharacteristicsX1.3.1 Consumable electrode vacuum-melted steels andalloys may contain discontinuities peculiar to this processwhich are disclosed upon macroetch examination.X2. ELECTROSLAG REMELTINGX2.1 Process DescriptionX2.1.1 Electroslag remelting (ESR) was first introduced inan American patent
49、by Hopkins, but most of the publishedwork has been done by Russian engineers. The process hasbeen shown to reduce inclusions, similar to vacuum-arc remelt-ing, with the additional benefit of reducing sulfur content incritical alloys for aerospace and nuclear applications. Manyvariations of processing parameters, equipment design, ingotsizes and shapes are used.X2.1.2 The ESR process consists of remelting a consumableelectrode through a bath of molten slag using the electricalresistance of the slag t
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