COMPARISON OF MICROSTRUCTURE AND WEAR RESISTANCE OF CR-TI-MO AND CR-V BASED HARDFACING ALLOYS FOR HIGH TEMPERATURE TOOL INDUSTRY

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1 COMPARISON OF MICROSTRUCTURE AND WEAR RESISTANCE OF CR-TI-MO AND CR-V BASED HARDFACING ALLOYS FOR HIGH TEMPERATURE TOOL INDUSTRY 1 Ankit Gupta and 2 Viheh Garg Delhi Intitute of Tool Engineering and Netaji Subha Intitute of Technology, New Delhi, India Eail : 1 yankitgupta@hotail.co, 2 viheh.1994@gail.co Abtract The adheive and abraive wear of cutting tool, drilling tool, ining equipent, piton rod, valve eat etc. can be decreaed by the Shielded Metal Arc Welding (SMAW) of hardfacing alloy on their urface. A tudy ha been undertaken to copare the wear reitance of Cr-Ti and Cr-Vanadiu baed hardfacing alloy a a function of Hardne, copoition, Carbide foration and icrotructure. According to the Optical and Scanning Electron Microcopy and ASTM G-77 & ASTM G-99 Standard wear tet, the reult how that the foration of ajorly (Cr,Ti) 7 C 3 carbide in addition with (Fe,Mo,Ti)C in the Cr-Ti-Mo baed alloy, ha the greater wear reitance than the (Cr, V)C 2, (Cr,V) 7 C 3 foration in Cr-V baed hardfacing alloy. The foration of (Fe, Ti)C change the icrotructure of the coating alloy fro hypereutectic to hypoeutectic which ha greater wear reitance in coparion to hypereutectic and Eutectic icrotructure. In addition to thi, Cr-Ti baed alloy how the icro hardne up to 750 HV, where a Cr-V baed alloy how the icro hardne up to 650 HV. In addition to the wear reitance, Ti-Mo baed alloy howed ore reitance to eroion and galling by reducing the tacking fault energy of the atrix or being a hcp tabilizer. Initial obervation howed the it ha the potential to replace the expenive Tungten and Cobalt alloy for high teperature wear condition. Index Ter Hardfacing alloy, icrotructure, Carbon Carbide, wear echani, I. INTRODUCTION Hardfacing alloy copoition i affected by the different type of wear in different application becaue of the eleent varying bonding trength and eroion rate. There are any type of wear to be conidered in the different application naing a few like, adheive wear (two etal urface in relative otion and in contact with each other under load), abraive wear (hard urface ove along the other under load), eroive wear (particulate ipact a urface cauing aterial to be reoved fro the urface), fatigue wear (due to repeated otion and treing by bearing load) and corroion wear. Thu ASTM ha developed any kind of tandard Tet Method for the different type of abraion, ASTM G76 (Eroion wear), ASTM G99 (Fatigue wear), ASTM G99-05 (Abraive wear), ASTM G77-05 (Adheive wear). For our appropriate reult we have done ASTM G77-05 and G99-05 for etal-etal wear and etal-earth wear condition. There are any icrotructure which influence the wear reitance propertie of the pecien like, bainite, aternite, ferrite, autenite, but carbide how the bet wear reitant propertie, with in which the priary M 7 C 3 or MC how the axiu reitant to wear than copletely eutectic tructure. The further addition of eleent like Molybendu, Titaniu and Vanadiu in high Chroiu baed alloy, increae the wear reitance and hot hardne propertie. Vanadiu exit in the for of (VCr 2 )C 2 whoe ize change fro refineent to coure. Wherea Titaniu exit in the for of TiC in autenite which hinder the dendrite developent. Molybendu play a good role in early carbide foration. 24

2 For the icrotructure characterization, the etallographic pecien i needed to be prepared by following five different tep: apling, ounting, grinding, polihing and etching. Sapling i the proper election of the pecien for the icrotructure analyi. After the iplication of hardfacing alloy coating by SMAW on the cat iron or S.S. plate, the pecien hould be cut to deired ize for ounting uing a laboratory abraive aw. And the hot ounting of the aple i carried out properly for the grinding and polihing. Grinding and polihing i carried out in an autoated achine, for the proper peed (RPM) of wheel at RPM, and grinding i done with a 220 or 240 and 500 grit ize SiC paper, which i followed by diaond polihing of 9 icroeter pate on a naple cloth, followed by 6 icroeter, 3 icroeter, 1icroeter and finally 0.25icroeter for the proper polihing. After every grinding tep, pecien i cleaned by tap water. The final tep etching i the ot iportant tep to be carried out to ee the icrotructure detail. There are any etchant ued, which depend on the copoition of the pecien. There are different type of etchant for different copoition and reult, naing a few like Nital, Picral, Glycerigia, Beraha cds, Murakai reagent, aqua regia, Beraha Martenite, Kle 1, Molybdate reagent, Selenic acid reagent etc. Fig. 1: Mounted and Polihed Hardfacing alloy 1(Cr-Ti- Mo) II. EXPERIMENTAL PROCEDURE A. Welding Condition and Material Copoition Two Hardfacing electrode wa developed, their repective copoition ha been given in Table 1. After extruion of the electrode, they were baked for 3-4 hour at 300 o C. Then, Hardfacing i done on ASTM A36 Steel plate by Shielded etal arc welding (SMAW). The copoition of ASTM A36 Steel plate i decribed in Table 2 and SMAW paraeter in Table 3. Only One coating of each copoition i applied on the different teel plate. SMAW wa carried out norally, with no coplication with adequate dilution rate and depoition rate. Table 1: Cheical Copoition of Electrode Approxiate Cheical Copoition Cr Si Ni Mn Mo Ti V Fe (wt %) Hardfacing facing alloy 1 (Cr-Ti-Mo) 11% 0.75% 0.60% 1.60% 0.80% 3.80% - Balance Hardfacing facing alloy 2(Cr-V) 8% 0.75% 0.60% 1.60% - - 5% Balance Table 2: Copoition of ASTM A36 Steel Plate (wt%) C Si S Cu P Fe Balance Table 3: SMAW Proce Paraeter Electrod e Current (A) Voltage (V) Speed( /in) No. of Layer Hardfaci ng alloy A 20V Hardfaci ng alloy A 20V Fig. 2: Mounted and Polihed Hardfacing alloy 2(Cr-V) B. Micro Hardne Meaureent Vicker Hardne Tet ethod wa ued to eaure the icro hardne of the variou icrotructure phae of both the pecien, in accordance with the ASTM E384 Standard. Reult of the tet i howed in the Table 4 for 25

3 Cr-Ti-Mo baed alloy and Table 5 for Cr-V baed alloy. Specien 1 how the Micro Hardne up to 750 HV and Specien 2 how icro hardne up to 650 HV. C. Metallography and Microtructure Characterization Microtructure analyi ha been done uing the Optical and Scanning Electron Microcope (SEM). Both the pecien were properly ounted, and then they were were grinded and polihed uing 9 icroeter diaond pate on naple cloth, which wa followed by 6 icroeter, 3 icroeter, 1 icroeter and 0.25 icroeter. etabiulfite for 70 econd.different carbide foration could be eaily recognized fro the Microtructure and further type of tructure have been decribed in the following figure. Fig. 3: (a) (b) Table 4: Reult of Vicker Hardne Tet for Specien 1, icro hardne i in HV. Mounted and Polihed Specien 1 and Specien 2 are hown in Fig. 1 & Fig. 2 repectively. Specien 1(Cr-Ti-Mo Baed alloy) wa etched with 2l HCL, 0.5 l elenic acid and 100l Ethyl Alcohol for 5 inute. (c) Table 5: Reult of Vicker Hardne Tet for Specien 2, icro hardne i in HV Specien 2 (Cr-V Baed alloy) wa etched with 50l of Sodiu Thioulphate and 1 gra of Potaiu 26

4 (d) (b) (e) (c ) (d) Fig. 3: Hardfacing icrotructure of Specien 1(Cr-Ti- Mo) a: 50x view how the (Cr,Ti)C carbide foration in large yellow pot, b: 50x view how the MoC carbide foration in all green pot, c: 20x view how the dendritic icrotructure foration. d & e: 10x view how the dendritic growth at the bae etal and welding boundary. Fig. 4 (a) (e) 27

5 Fig. 4: Hardfacing icrotructure of pecien 2(Cr-V) a: 100x view how the (Cr,M) 7 C 3 carbide foration in large white pot with black lining, b: 100x view how the (V,Cr 3 M)C 2 carbide in all patche. c: 50x view how the (Cr, V) 7 C 3 carbide and (Cr, V)C 2 carbide. d & e: 20x view how the preence of other alloying eleent like: Si, Mn and Ni Before tarting the tet, pecien wa cleaned in an ultraonic bath and then rined in the ethanol olution. Another ASTM G99-05, Pin on Dic Method, tandard tet ethod wa carried to do the wear teting both the aple. Standard teting paraeter (RPM of Pin & Dic and Noral load applied) along with the dienion of Pin and Dic ha been pecified in the Table 7Fig. 6 how the cheatic of Pin on Dic ethod. The reult were deterined by the weight lo with 0.1 g reolution of both the aple in the above entioned two tandard tet. And it wa found out that Cr-V baed alloy aple ha approxiately 15% ore weight lo than the Cr-Ti-Mo baed alloy aple. Thu clearly howing the Hardfa cing alloy 1 Rin g Spe ed 1/ Nor al Load 25N Rin g O.D. 35 Block Lengt h Brea dth 1 Widt h 6.35 Hardfa cing alloy 2 1/ 25N Table 6: ASTM G-77 teting paraeter and Standard ring & block dienion Dic RP M Nora l Load Pin Dia Dic Thickne Dic Dia Hardfacin g alloy 1 80 RP M 20N Fig. 5: Scheatic of the Block on Ring Tet Method, ASTM G-77 Standard ethod. Wear Tet ASTM G-77-05, Block on the Ring Method, tandard tet ethod wa carried to do the wear teting both the aple. Standard teting paraeter (Speed of Ring and Noral load applied) along with the dienion of Block (Specien) and the ring ha been pecified in the Table 6. Fig. 5 how the cheatic of the Block on Ring Tet Method. Hardfacin g alloy 2 80 RP M 20N Table 7: ASTM G-99 teting paraeter and Standard dienion of Pin and Dic 28

6 Fig. 6: Scheatic of the Pin on Dic Tet Method, ASTM G-99 Standard ethod. Better ear reitance of pecien 1. III. RESULTS AND CONCLUSION Microtructure: Microtructure of Specien 1(Cr-Ti-Mo baed alloy), etched with 2l HCL, 5l Selenic Acid and 100l Ethyl Alochol for 5in., the iage clearly how the foration of (Cr,Ti)C foration in 50x view, while the inor pot how the preence of other alloying eleent like Si, Ni, Mn, S. Initial iage how the high Chroiu rich pot, which ha the eutectic icrotructure. Sall green pot how the foration of MoC in the econd iage. 20x view of third and fourth iage, how the dendritic icrotructure growth due to the Chroiu carbide foration, and it can be oberved that there i a tranforation of eutectic icrotructure to hypoeutectic icrotructure due to the foration of Titaniu carbide. Thi dendritic growth at the boundary of weldent and bae etal increae the bond trength which further help in wear reitance. Micro Structure of Specien 2(Cr-V baed alloy), wa etched with 50l of Sodiu thioulphate and 1g of potaiu etabiulfite for 60 econd. Iage clearly how the foration of Cr 7 C 3 and Cr 23 C 6 carbide in the initial iage of 100x and further iage how the (Cr, V)C 2 carbide foration in the all patche. Thee icrotructure ha the proeutectic tructure, where hardne value i in between HV. And further iage of 50x and 20x view how the preence of other alloying eleent in very finite colored pot. Wear Reitance: Both the Block on Ring and Pin on Dic ASTM tandard wear tet ethod have hown that hardfacing alloy baed on Chroiu-Titaniu and Molybendu ha greater wear reitance than hardfacing alloy baed on Chroiu-Vanadiu. Preence of rich M 7 C 3 coare tructure carbide in the pecien 1 reduce the chance of cutting and grooving in addition to it, preence of MC prevent the reoval of M 7 C 3 which enhance the wear propertie and reduce the etal reoval rate. Thu it can be concluded that wear reitance of any hardfacing alloy depend ajorly on the type and ditribution of carbide and their icrotructure atrix. And it further influence the Hardne and other echanical propertie. IV. REFERENCES [1] Janina Radzikowka, Metallography and icrotructure of cat iron, p [2] Guide to Engineered Material, Property Coparion Table, Adv. Material. Proce., Vol 159 (No. 12), Dec 2001, p 20 [3] S. Chatterjee, T.K. Pal, Wear behavior of hardfacing depoit on cat iron, Wear 255 (2003) [4] W. Wo, L.-T. Wu, The wear behavior between hardfacing aterial, Metall. Mater. Tran. A 27A (1996) [5] Q.Wang and X. Li, Effect of Nb, V and W on icrotructure, welding journal July, P to