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Structure and Properties of Thermite Welds in Premium Rails 6 PB86168556 1111111111111111111111111111111 Structure and Properties u.s. Department of Thermite Welds in of Transportation Federal Railroad Premium Rails Administration' Office of Research and Development Washington DC 20590 L. C. Schroeder D. R. Poirier The Department of Metallurgical Engineering The University of Arizona Tucson AZ 85721 DOT/ FRA/ORD-85/02 December 1985 This document is available to the DOT-TSC-FRA-84-4 Final Report Public through the National Technical Information Service. Springfield. Virginia 22161. REPRODUCED Ity ,~~I~~A!-.lECHNICAl lI'IrUII:MA I ION SERVICE u.s. DEPARTMENT OF COMMERCE SPRINGFiElD, VA. 221&1 NOTICE This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. NOTICE The United States Government does not endorse products or manufacturers. Trade or manufacturers' names appear herein solely because they are considered essential to the object of this report. Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. DOT/FRA/ORD-85/02 PB8 b 1 6 8 5 5b lAS 4. Title and Subtitle S. Report Dot. December 1985 STRUCTURE AND PROPERTIES OF THERMITE WELDS IN PREMIUM RAILS 6. Performing Orgoni lotion Code DTS-76 h~~~~~~~~~~~~~~~~~~~~~~~~~~~~~8.PM~rmingO~~iuti_R~~No. 7. Aumorl ,) L.C. Schroeder and D.R. Poirier DOT-TSC-FRA-84-4 9. Performing Orgoni lotion Name and Address 10. Work Unit No. (TRAIS) *The Department of Metallurgical Engineering RRS19/RS304 The University of Arizona J1. Contract or Grant No. Tucson, AZ 85721 DOT-TSC-1567 13. Type of Report and P.riod Cov.red. r--:-:~~-----------------------..j , 2. Sponsoring Agency Name and Address Final Report U.S. Department of Transportation Federal Railroad Administration Office of Research and Development 14. Sponsoring Agency Code Washington, DC 20590 RRD-10 15. Supplementary Note. U.S. Department of Transportation Research and Special Programs Administration *Under contract to: Transportation Systems Center Cambridge MA 02142 , 6. Abstract Thermite welds were used to join combinations of premium rails and AREA Controlled Cooled Carbon rails (i.e., standard rails). The premium rails comprised head-hardened rails and CrMo, CrV and Cr alloy rails. A major objective was to determine the feasibility of joining premium rails to each other and to standard rails with the thermite welding process. The objective was met in that metallurgically sound welds were produced using either "standard" or "alloy" thermite charges. Other objectives were to determine mechanical properties and metallurgical structures of the weld-metal and of the heat-affected zones. The "alloy" weld-metal was stronger than "standard" weld metal but had less tensile ductility. Both types exhibit ductilities of only 2-6 percent reduction in· area and impact o energies of only 1.5-2.8 Joules at 20 C. Tensile and impact specimens, which straddled the region of minimum hardness at the outer edge of the heat affected zone, show tensile ductilities of 19-60 percent reduction in area and only 2.6-6.9 Joules for impact energy. In addition, temperature in the rail near the weld metal was measured as four of the welds were produced; in a fifth, temperatures in the weld metal, itself, were measured. Finally, residual stresses were determined, and their effect on fatigue strength of welded rail is discussed. ' 17. Key Word. 18. Distribution Stotemant Rail, Thermite-Welding, Premium DOCUMENT IS AVAILABLE TO THE PUBLIC Rails, Mechanical Properties, THROUGH THE NATIONAL TECHNICAL Residual Stresses INFORMATION SERViCe. SPRINGFIELD. VIRGINIA 22161 19. Security ClassH. (of this repor') Poge 22 Price 20," secuUri::CCL10~:SSifS' (IOfF'hIi 'D ) ./21. No,'2°2' Pages 1 • J.JN~LASSIFJ$I)_, L~ ~'1. 1_ ,," .1, E l , __________....L- L l_' ----" Form DOT F 1100.1 (8-72) Reproduction of complet6d poge outhorized PREFACE This report was prepared by L. C. Schroeder and D. R. Poirier of the Department of Metallurgical Engineering, The University of Arizona. The technical monitor was Mr. James Morris of the Transportation Systems Center in Cambridge, Massachusetts. Dr. Roger K. Steele, then of the Federal Railroad Administration, Transportation Test Center in Pueblo, Colorado graciously arranged for the thermite-welding at the FAST facility in Pueblo. Messrs. Morris and Steele generously made themselves available for technical consultation for the duration of the project. Their assistance is gratefully acknowledged. Preceding page blank iii METRIC CONVERSION fACTORS App•••I.... c••"••a1... •• M••rlc M....... .. - ~ A" IC••"I••• ,... M"rlc M . s--:: I,.,., •••• ,.. •••• ...111,1, " T. I'.... I,.... •... ,••_ ........, " ,. ,... I'.... = .. fl.. - .. - ~ .. LENGTH a LENGTH -- _ ..iUi_'... .... iRc.... I. :: an e...U...... 0.. inc.... i. - .. _,... 2.2 .... h .. "2.' -,~,.. COlI - == :=.... _,... 1.1 ,.nt. yd II :Ill CIft'O""1II _.. =- .. ki_... •.• mile. .1 .,. ,ant. 0.' _.... "'-=- _ • ";1.. 1.1 ki........... iiL- ::: == AREA AREA _ = :I I • = rJ _ .......,...... '.11 __ .. ..I _ ••• _'" clllti...... rJ = ..1 _ ••_I... 1.2 aq ,ant. .,; "I _. .... _.. .........2 _ ..2 _ .. kil....'.. •.• aq i1.. ",2 .,.,a _-,..... ••• _........ .". • loa hac.....,0.000 .11 2.. •. roil _ .,.. 2.' ell"'" lIil__ ".". _ ... _.. •.• ......... ... - = .. .. ;:;.. MASS (w.I"'1 ...<" MASS (w.i,··1 -::: !2 =-- • .._ 1.031 ounc" .. .. _. 21 .-. e= kt kilogr_ 2.2 pound. .. .. 0." kilogr_ kl ::, _.11000 ktI 1.1 _ '0.. ......, 0.' _... "'-'i:---- IZOOO", • = 0 VOLUME _ a- .. VOLUME = • • onillUiI..... g-.. .milil.. 1.'2 ".dld _. II 01 .... ..._. ,. 2 1 pont. III Tbap "b' 11 Illillilit.....1 - = ... II... .1 01 'Iu':=~ :Ill ..iUili.... "".. ~ I Ii'... 1.111 _rt. ... c c.... 0.2' 'i'... I '-.. 1 10,... 0.2' lIlOlI.on. ~' pi pin,. 0.'7 lit... 1 ;;;;;- ..) cubic l1li'.. 3. cub~c ,... h ) II' "".... 0.95 II,..., -....) cubic 1111'.' 1.2 cubiC ,ani. yd ';' lIlOlIon. U Ill... ') _ ~ .. c.... ~c '"' 0.02 cUb~C 11111.. '" .. TEMPERATURE (IIIC" , ..) cuboc ,lid. 0.1' cubIC mI'''. ",2.. =- _. TEMPERATURE (•••c" - .'c C.,.Iu. .111_ ' ..........1' ", _ ,__ _ 221 '_'.'- " ' ..........1. iI'.1". C.I.iu. 'c __ .. • temper.lUre I""'r.cliot l.mpera'WI .... -- , 221 __ .. I, 22 .... 212 -40 0 !40 .0 l 120 1.0 aoa J con\l'''kJ~ ~.;;; 'ai~ ,~ ,.~I -, In • 2.54 tel&llcllvl. f ... 01"-' ...e' Mtd PlUf. dilla.led '.-bIn. seo NBS MISC. "ubi. 2N. i· =... _I' it '.' l' I 'I' (;0' '. • ' ••' ',' Ito Unl" of ".,ghe. and ....SUf••• 'uc.I2.25. ~ C."IOQ No. Cll.IO.2So. ! _! ~g 31 C Ill. TABLE OF CONTENTS Section 1. I NTRODUCT I ON ••••••••••••••••••••••••••••••••••••• 1 1.1 Statement of the Problem.................... 1 1.2 Objective of this Study..................... 2 2. REVIEW OF RELATED STUDIES •••••••••••••••••••••••• 4 2.1 Application of the Aluminothermic Process... 4 2.2 Alternative Reductants to Aluminum.......... 4 2.3 Additives that Affect the Aluminothermic Process. .................................... 5 2.4 Thermite Rail-Welds......................... 7 2.5 Weld Integrity.............................. 10 2.6 Residual Stresses in Welds.................. 16 3. EXPERIMENTAL PROCEDURES •••••••••••••.•••••••••••• 19 4. RESULTS AND DISCUSSIONS •••.••••••••••.•.••••••••• 23 4.1 Mechanical Properties....................... 23 4.1.1 Hardness Profiles••••••••••••.••••••• 23 4.1.2 Impact Properties ••.••••••••••••••••• 24 4.1.3 Tensile Properties •.••••••••••••••••• 25 4.1. 4 Fractography of Impact and Tensile Specimens .•••.•••.••••••••••. 26 4.1.4.1 Charpy V-Notch Specimens in the HAZ.................. 27 4.1.4.2 Charpy V-Notch Specimens in the Weld Metal........... 28 4.1.4.3 Tensile Specimens in the HAZ 29 4.1.4.4 Tensile Specimens in the Weld Metal.................. 30 4.2 Structural Analyses......................... 31 4.2.1 Macrostructures •••••.•••••.•••••••••• 31 4.2.2 Microstructures •••••••••••••••••••••• 33 4.2.3 Inclusion Evaluation••••••••••••••••• 34 4.3 Thermal Measurements........................ 36 4.4 Residual Stresses........................... 39 v TABLE OF CONTENTS (CONT.) Section Page 5. CONCLUSIONS.................................... 43 6 • REFERENCES. ••••••••••••••••••••••••••••••• .• •••• 47 APPENDIX - THERMITE WELDING (FIELD WELDING).............. 55 vi LIST OF ILLUSTRATIONS Figure 1 RESIDUAL STRESSES IN A NONREINFORCED THERMITE RAIL-WELD.......................................... 59 2 MOLD CONFIGURATION AND FLOW PATTERN OF THE MOLTEN STEEL FOR THE THERMITE RAIL-WELDS •••••••••••••••••• 60 3 THERMOCOUPLE LOCATIONS FOR WELDS 1, 2 AND 4 •••••••• 61 4 LOCATIONS OF THERMOCOUPLES IN THE WELD METAL OF WELD 9.......................................... 62 5 LOCATIONS OF TENSILE AND IMPACT SPECIMENS, HARDNESS PROFILES AND MICROSTRUCTURE SPECIMENS IN WELDS................................. 63 6 LOCATIONS OF STRAIN GAUGE ROSETTES FOR RESIDUAL STRESS MEASUREMENTS................................ 64 7 HARDNESS PROFILES OF WELDS 1, 4 AND 7 ..•••.•..••.•• 65 8 HARDNESS VARIATIONS IN THE HAZs OF ALLOY RAILS RELATIVE TO THE HARDNESS OF PARENT RAIL •••••••••••• 66 9 HARDNESS VARIATIONS IN THE HAZs OF STANDARD AND OF HEAD-HARDENED RAIL RELATIVE TO THE HARDNESS OF PARENT RAIL........................................ 67 10 HARDNESS OF THE WELD METAL AS A FUNCTION OF PREHEAT TIME AND DISTANCE FROM THE WELD CENTERLINE ••••••••• 68 11 FRACTURE OF IMPACT SPECIMEN THROUGH THE REGION OF MINIMUM HARDNESS IN THE HEAT-AFFECTED ZONE ••••••••• 69 12 FRACTURE SURFACE OF FIGURE 11: (a) ORIGINAL
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