AWS PRGHF-2002 The Practical Reference Guide for Hardfacing《硬化堆焊的实践参考指南》.pdf

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1、The PracticalReference Guide for550 N.W. LeJeune Road, Miami, Florida 33126THE PRACTICALREFERENCE GUIDEforHARDFACINGCompiled/Edited byLee G. KvidahlManager, Welding and Manufacturing EngineeringIngalls Shipbuilding OperationsNorthrop Grumman CorporationThis publication is designed to provide informa

2、tion in regard to the subject matter covered. It is made availablewith the understanding that the publisher is not engaged in the rendering of professional advice. Reliance uponthe information contained in this document should not be undertaken without an independent verification ofits application f

3、or a particular use. The publisher is not responsible for loss or damage resulting from use of thispublication. This document is not a consensus standard. Users should refer to the applicable standards for theirparticular application.iiPhotocopy RightsAuthorization to photocopy items for internal, p

4、ersonal, or educational classroom use only, or the internal,personal, or educational classroom use only of specific clients, is granted by the American Welding Society(AWS) provided that the appropriate fee is paid to the Copyright Clearance Center, 222 Rosewood Drive,Danvers, MA 01923, Tel: 978-750

5、-8400; online: http:/ 2002 by the American Welding Society. All rights reserved.Printed in the United States of America.EDITOR NOTESThe editor would like to thank the AWS Product Development Committee for sponsoring this publication. Aspecial thanks, also, to Dr. Ravi Menon, Stoody Co., Bowling Gree

6、n, Kentucky (a Thermadyne company) forhis suggestions.iiiTABLE OF CONTENTSPage No.Basic Safety Precautions . ivIntroduction1Hardfacing Applications 1Hardfacing Properties.2Selection of Hardfacing Materials.2Hardfacing Processesthe Effect of Welding Variables on Dilution7Other Publications Available

7、from AWS .15LIST OF TABLESTable Page No.1 Common Surfacing Processes and Materials.12 High-Speed Steel Filler Metals.33 Austenitic Manganese Filler Metals 34 Austenitic High Chromium Iron Filler Metals 45 Cobalt Base Alloy Filler Metals56 Copper Base Alloy Filler Metals 67 Nickel Chromium Boron Allo

8、y Filler Metals.78 Tungsten Carbide Filler Metals89 Shielded Metal Arc Process VariablesIndependent Effects on Key Surfacing Characteristics 910 Gas Tungsten Arc Process VariablesIndependent Effects on Key Surfacing Characteristics.1011 Gas Metal Arc Process VariablesIndependent Effects on Key Surfa

9、cing Characteristics .1112 Submerged Arc Process VariablesIndependent Effects on Key Surfacing Characteristics.12LIST OF FIGURESFigure Page No.1 Different Impingement Angles 82 Calculation of Base Metal Dilution93 Effect of Travel Speed on Dilution (Other Conditions Unchanged) 134 Basic Surfacing Os

10、cillation Techniques and Bead Configurations.135 Uphill and Downhill Welding Flat Plate and Rotating Cylindrical Parts .146 Map of Hardfacing Applications.14ivBASIC SAFETY PRECAUTIONSBurn Protection. Molten metal, sparks, slag, and hot work surfaces are produced by welding, cutting, andallied proces

11、ses. These can cause burns if precautionary measures are not used. Workers should wear protec-tive clothing made of fire-resistant material. Pant cuffs, open pockets, or other places on clothing that cancatch and retain molten metal or sparks should not be worn. High-top shoes or leather leggings an

12、d fire-resistant gloves should be worn. Pant legs should be worn over the outside of high-top shoes. Helmets orhand shields that provide protection for the face, neck, and ears, and a head covering to protect the headshould be used. In addition, appropriate eye protection should be used.Electrical H

13、azards. Electric shock can kill. However, it can be avoided. Live electrical parts should not betouched. The manufacturers instructions and recommended safe practices should be read and understood.Faulty installation, improper grounding, and incorrect operation and maintenance of electrical equipmen

14、t areall sources of danger.All electrical equipment and the workpiece should be grounded. The workpiece lead is not a ground lead. Itis used only to complete the welding circuit. A separate connection is required to ground the workpiece. Theworkpiece should not be mistaken for a ground connection.Fu

15、mes and Gases. Many welding, cutting, and allied processes produce fumes and gases which may beharmful to health. Avoid breathing the air in the fume plume directly above the arc. Do not weld in a con-fined area without a ventilation system. Use point-of-welding fume removal when welding galvanized

16、steel,zinc, lead, cadmium, chromium, manganese, brass, or bronze. Do not weld on piping or containers that haveheld hazardous materials unless the containers have been inerted properly.Compressed Gas Cylinders. Keep caps on cylinders when not in use. Make sure that gas cylinders arechained to a wall

17、 or other structural support. Do not weld on cylinders.Radiation. Arc welding may produce ultraviolet, infrared, or light radiation. Always wear protective cloth-ing and eye protection to protect the skin and eyes from radiation. Shield others from light radiation fromyour welding operation.Ventilat

18、ion During Welding. Five major factors govern the quantity of fume to which welders and weldingoperators are exposed during welding:(1) Dimensions of the space in which welding is done (with special regard to the height of the ceiling)(2) Number of welders and welding operators working in that space

19、(3) Rate of evolution of fumes, gases, or dust, according to the materials and processes involved(4) The proximity of the welder or welding operator to the fumes as they issue from the welding zone, and tothe gases and dusts in the space in which he is working(5) The ventilation provided to the spac

20、e in which the welding is doneRefer to the section entitled, “Ventilation” in American National Standard ANSI Z49.1, Safety in Welding,Cutting, and Allied Processes for a discussion on the ventilation that is required during welding.Special Precautions. In the following conditions when using thermal

21、 spraying:(1) The main source of hazard during the thermal spraying operation is the intense heat produced by thespray gun.(2) The heat combines with other factors to produce additional secondary hazards. These include: dust andmist; radiated light, infrared and ultraviolet; and high intensity noise

22、.(3) Grit blasting, performed for surface preparation, provides hazardous conditions: high velocity air andgrit stream, dust from blast impact, and loud noise.Caution must be exercised in protective clothing, safety glasses and shoes, and eye and ear protection. AWSrecommends a personal copy of “Arc

23、 Welding Safely,” “Fire Safety in Welding and Cutting,” “Safety in Weld-ing, Cutting and Allied Processes,” “Thermal Spray Manual,” “Arc Welding and Cutting Noise,” and “LensShade Selector.” See Ordering Information under “Other Publications Available from AWS.”HardfacingAWS Practical Reference Guid

24、e 1IntroductionHardfacing is one category from the family of surfac-ing processes. Surfacing is defined in AWS A3.0,Standard Welding Terms and Definitions, as “The appli-cation by welding, brazing, or thermal spraying, of alayer, or layers, of material to a surface to obtaindesired properties or dim

25、ensions, as opposed tomaking a joint.” The surfacing processes may begrouped as surface cladding, buildup, buttering, andhardfacing. These processes are defined as follows:Cladding. A surfacing variation that deposits orapplies surfacing material usually to improvecorrosion or heat resistance.Buildu

26、p. A surfacing variation in which surfacingmaterial is deposited to achieve the requireddimensions.Buttering. A surfacing variation that deposits sur-facing metal on one or more surfaces to providemetallurgically compatible weld metal for thesubsequent completion of the weld.Hardfacing. A surfacing

27、variation in which surfac-ing material is deposited to reduce wear. (A non-standard term for hardfacing is hard surfacing.)Hardfacing ApplicationsIn hardfacing applications, a layer of surfacingmetal is applied to reduce wear by increasing theresistance of a metal surface to abrasion, impact,erosion

28、, galling, or cavitation. As with cladding, thestrength of hardfacing is not considered in the de-sign of the component (see Table 1).In addition to the characteristics of the surfacingmaterial and base metal, other important consider-ations when choosing hardfacing applications are:(1) Geometry of

29、the part to be surfaced(2) Cost of the material and labor(3) Techniques to prevent cracks in the surfacing orapplication-generated cracks(4) Techniques to minimize distortion from thethermal stresses of welding(5) Quality of the depositTable 1. Common Surfacing Processes and MaterialsProcess Mode of

30、 Application Surfacing Metal FormsOxyfuel gas (OFW) Manual or semiautomatic Powder and bare cast and tubular rodsShielded metal arc (SMAW) Manual Covered electrodes, solid cast electrodes, and tubular electrodesFlux cored arc (FCAW) Semiautomatic or automatic Composite electrode of metallic sheath a

31、nd powder coreGas metal arc (GMAW) Semiautomatic or automatic Bare solid and tubular electrodesSubmerged arc (SAW) Automatic Bare solid and tubular wires and stripGas tungsten arc (GTAW) Manual or automatic Powder, bare solid and tubular wires, and bare cast rodsPlasma arc (PAW) Automatic Powder and

32、 bare and tubular wiresThermal Spray ProcessesFlame spraying (FLSP) Semiautomatic or automatic Powder and bare and tubular wiresPlasma spraying (PSP) Semiautomatic or automatic PowderArc spraying (ASP) Semiautomatic or automatic Bare and tubular wiresHigh-velocity flame Semiautomatic or automatic Po

33、wder2 AWS Practical Reference GuideHardfacingHardfacing PropertiesProperties of the hardfacing process are as follows:HardnessMacrohardness (gross hardness)Microhardness (hardness of individual constitu-ents in a heterogeneous structure)Hot hardness (resistance to the weakening effectof service at e

34、levated temperature during shorttime loading)Creep resistance (resistance to plastic deforma-tion when loaded at elevated temperatures forrelatively long periods of time)Abrasion ResistanceUnder low stress (scratching wear)Under high stress (grinding)Under high stress and impact (gouging)Impact Resi

35、stanceResistance to plastic deformation under repeatedimpact loading (related to yield strength andfatigue strength)Resistance to cracking under impact loading (re-lated to ductility but including work-hardeningconsiderations)Heat ResistanceResistance to tempering (softening with time attemperature)

36、Retention of strength when hot (including hothardness)Creep resistance (time factor added to hotstrength)Resistance to oxidation or corrosion by hot gasesCorrosion ResistanceMetal-to-Metal ResistanceFriction coefficients (relative ease of sliding)Galling tendency (localized welding)Surface films (ox

37、ide layers)Lubricity (slipperiness)Plasticity (ability to deform)Erosive Wear ResistanceUnder high-angle solid particle impingementUnder low-angle solid particle impingementUnder liquid droplet erosionUnder cavitation conditionsHardfacing AdvantagesWhen compared with other surfacing processes,hardfa

38、cing has the following advantages:(1) Additional resistance to wear or corrosionexactly where it is needed(2) Ready application in the field(3) Economical use of expensive alloys(4) A hard surface layer to resist wear that is sup-ported by a tough substrate to carry the loadSelection of Hardfacing M

39、aterialsFactors to be identified for selection of surfacingmaterials (see Tables 28) includes:The type of abrasive to be encountered and itscharacteristics (hardness, sharpness, particlesize, and toughness)The amount of impact to be encounteredThe amount of support provided to the depositThe levels

40、of stress involvedThe nature of the stress (tensile, compression, orshear)The operating temperatureOther significant environmental conditionsImpact ResistanceImpact may be classified as light, medium, or heavy,depending upon the result of the impact energy.An example of a heavy impact application is

41、 ahardfaced mill hammer. In light impact, kinetic en-ergy is absorbed elastically. It is absorbed both elas-tically and plastically in medium impact. In heavyimpact, the surface of even the strongest materialsmust either deform or fracture.HardfacingAWS Practical Reference Guide 3Table 2. High-Speed

42、 Steel Filler MetalsProperties CharacteristicsHardness The Rockwell hardness of the undiluted filler metals, in the as-welded condition, is in the range of C 55 to C 60.Hot Hardness At temperatures up to 1100F (595C), the deposited Rockwell hardness of C 60 falls off very slowly toapproximately C 47

43、. At higher temperatures, it falls off more rapidly. At about 1200F (650C), the maxi-mum Rockwell hardness is about C 30.Impact These filler metals can withstand only medium impact without cracking in the as-welded condition. Aftertempering, the impact resistance is increased appreciably.Oxidation R

44、esistance Because of high molybdenum content, these filler metals will oxidize readily. A non-oxidizing furnaceatmosphere salt bath or borax coating should be used to prevent decarburization when heat treatmentsare required.Corrosion Resistance The weld metal can withstand atmospheric corrosion, but

45、 it is not effective in providing resistance to liquidcorrosion.Abrasion The high stress abrasion resistance of the materials, as deposited and at room temperature, is much bet-ter than low carbon steel. However, they are not considered high abrasion resistance alloys. Resistance todeformation at el

46、evated temperatures up to 1100F (593C) is their outstanding feature, and this may aidhot abrasion resistance.Metal-to-Metal Wear Deposits are well suited for metal-to-metal wear, especially at elevated temperatures. They have a lowcoefficient of friction and the ability to take a high polish and ret

47、ain their hardness at elevated tempera-tures. The compressive strength is very good and will fall or rise with the tempering temperature used.Mechanical Properties in CompressionDeposits are well suited for metal-to-metal wear, especially at elevated temperatures. They have a lowcoefficient of frict

48、ion and the ability to take a high polish and retain their hardness at elevated tempera-tures. The compressive strength is very good and will fall or rise with the tempering temperature used.Machinability After deposition, these materials often have to be annealed for machining operations. For machi

49、nability,when thoroughly annealed, they are rated at 65as compared to 1% carbon tool steel, which has a ratingof 100. Full hardness can be regained by heat treating procedures.Identification In the hardened or as deposited condition, these materials are highly magnetic. When spark tested, theygive off a very small, thin stream of sparks approximately 60 in. (1500 mm) long. Close to the grindingwheel, the spark is red; at the end, it is straw color.Table 3. Austenitic Manganese Filler MetalsProperties CharacteristicsHardness The normal hardness of these weld dep