Carbide Spray Coating Influence on Wear Behaviorof Carburized Steel against Two Counter-Rollers

Liu-Ho Chiu1,+, Shu-Hung Yeh1, Bo-Rong Chen1 and Heng Chang2

1Department of Materials Engineering, Tatung University, Taipei 10451, Taiwan2Department of Mechanical Engineering, Chinese Culture University, Taipei 11114, Taiwan

The wear behavior of carburized SNCM 220 steel subjected to cold treatment and carbide spray coating is investigated. WC/Co coatings in15 « 5µm thickness were deposited on SNCM 220 specimens in a high velocity oxy-fuel (HVOF) process. Specimens were subjected to weartest under normal loads of 95.9N at 180 rpm on a dry block-on-roller tester and to two different counter-roller materials with hardness values of42 and 60 HRC. Wear test result after 12 h showed that the cumulative mass loss measurement of carburized SNCM 220 under 188K subzerotreatment was 15mg, improved from 37mg mass loss of SNCM 220 steel without cold treatment. In addition, the cumulative mass loss ofcarburized SNCM 220 specimens with sprayed carbide coating decreased from 37mg to 4mg. Moreover, wear tested specimens with HVOFcoatings countered with 42 HRC rollers have resulted higher mass losses than those countered with 60 HRC rollers. Analysis of the wearmicrostructures has revealed the effects of the cold treatment and HVOF coatings. It has shown that 42 HRC counter roller induced plasticdeformation on the specimen surface, which is detrimental to the specimen wear resistance. The compatibility of counter-roller and specimenhardness becomes the major factor to improve the wear of SNCM 220 steel. [doi:10.2320/matertrans.M2014230]

(Received June 24, 2014; Accepted December 22, 2014; Published February 25, 2015)

Keywords: carburizing, carbide, coating, wear, counter-roller

1. Introduction

Carburizing is a heat treatment process in which iron orsteel absorbs liberated carbon when the metal is heated in thepresence of a carbon bearing material. Carburizing is widelyused to improve steel wear and fatigue resistance. Benselyet al. investigated the wear resistance of case carburized steel(En 353) under cryogenic treatment.1) The samples wereprocessed using three different treating conditions, namelyconventional heat treatment (CHT), shallow cryogenic treat-ment (SCT) and deep cryogenic treatment (DCT). It wasfound that the wear resistance increased considerably withshallow and deep cryogenic treatments compared to conven-tional heat treatment. Kim et al.2) carried out a dry slidingwear behavior study of carburized AISI 8620 steel on a ring-on-square tester. The test results showed that the influence ofretained austenite was negligible at 20 kg load condition,while the wear resistance decreased at 40 kg load as theretained austenite content increased from 6% to 30%. Sainiet al.3) investigated the WC/C PVD coating effect on thefatigue behavior of case carburized SAE8620 steel. Theirresults pointed out that the coating leads to 7% gain inendurance limit without considerably affecting the hardnessand tensile strength.

Cold treatment such as cryogenic or subzero treatment isan effective way to improve the properties of alloy or toolsteels, and is widely used for high precision components.Several published studies indicated that cold treatment couldimprove the wear resistance of tool steels,4­6) and that thewear resistance increased with decreased carbide size,because adhesive wear is the main failure mode in thosesteels. A smaller carbide size distribution in the matrix coulddecrease the adhesion phenomena on the surface.7) Hence,exploration of cold treatment to enhance the wear resistanceof carburized steel has become a current research interest.8,9)

It has been found that wear resistance is increasedconsiderably with subzero treatment.

WC-Co cermet surface coatings are used extensively toimprove the wear resistance of engineering parts andcomponents.10,11) WC-Co surface coatings are deposited bythermal spraying or high velocity oxy-fuel (HVOF) processthat bonds WC-Co coatings to the substrate with minimalporosity on the surface. Several factors such as carbide grainsize, cobalt and carbon content play important roles indetermining the wear performance of sintered cermets.12­14)

The preparation and characterization of WC-Co cermets witha micro-scale grain structure were reported by Zhao et al.15)

The benefit of cold treatment on tool steel for wearresistance enhancement has been cited by several researchers.However, the wear resistance enhancement effects of sprayedcarbide coating on subzero treated steel have yet to be clearlyestablished. The aim of the study is to improve the wearresistance of a driver blade block made of carburized JISSNCM 220 steel, used in an electrical nail gun. The driverblade block is processed by carbide spraying coating and isdriven by contacting to a steel belt pulley hardened to 40HRC. The wear behavior between the block and pulley issimulated and analyzed using a block-on-roller dry weartest. The effects of carbide spraying and cold treatmentprocesses on the wear behavior of the carburized JIS SNCM220 steel specimens using a block-on-roller dry wear testare investigated. Carburized SNCM 220 steel specimenswere subjected to two different counter-roller materials withhardness values of 42 and 60 HRC. The cumulative massloss and microhardness characteristics were measured,together with wear surface morphology, microstructure, andsurface roughness using standard experimental procedures.

2. Experimental Procedures

2.1 Materials and processingCommercially available SNCM 220 (AISI 4320) steel bars+Corresponding author, E-mail: lhchiu@ttu.edu.tw

Materials Transactions, Vol. 56, No. 3 (2015) pp. 333 to 339©2015 The Japan Institute of Metals and Materials

were machined into cubic blocks with 12.7mm © 12.7mm ©12.7mm dimensions. Table 1 shows the chemical composi-tions of the steel specimens analyzed using a glow-dischargeoptical emission spectroscope (LECO, GDOES-750). TheSNCM 220 specimens were carburized, followed by coldtreatment and HVOF spraying. During the carburizingtreatment, the RX (Air + C3H8) gas generator chamberatmosphere was filled with a mixture of C3H8 and air whichproduced N2, CO and H2 of RX gas. The carburizing processwas conducted at 1198K for 1 h by adjusting RX gas andC3H8 in the UBE-MM-2 furnace, followed by diffusingat 1143K for 30min and subsequent oil quenching. Thecarburized specimens were under cold treatment at 188K or153K for 1 h, followed by tempering at 473K for 1 h. Thespecimens subjected to different treatments are referred towith the codes shown in Table 2.

2.2 Structure analysisThe cross-section microstructures of the specimens were

recorded on an optical microscope (OM). The phasespresented in the specimen surfaces were characterized usingan X-ray diffractometer with Cu-K¡ radiation source overthe 2ª range from 20° to 120°. The volume fraction ofretained austenite in the treated specimens was estimated inaccordance with ASTM standard E975-0016) by an X-raydiffractometer.

2.3 Hardness and wear testMicrohardness was measured using a Vickers microhard-

ness tester under 300 g load. Wear tests were deployed toinvestigate the treated specimen wear resistance behaviorusing a non-lubricated block-on-roller tester. Figure 1 showsa schematic diagram of the wear tester. One of the counterrollers, ¼ 60 © t 7.6mm in size, was made of JIS SKS3 (AISIO1) tool steel with a hardness of 60 HRC. A second counterroller of the same size was made of hardened and temperedJIS SNCM 439 (AISI 4340) steel with hardness of 42 HRC.The wear tests were conducted under normal load of 95.9Nat counter-roller rotation speed of 180 rpm for 12 h at roomtemperature. The surface roughness of the worn-out/as-received specimens was recorded using a MITUTOYOSURFTEST-III Surface Analyzer. The worn-out surfaces ofthe specimens were subsequently examined under a scanningelectron microscope (SEM) to identify the possible wearmechanisms.

3. Results and Discussion

3.1 MicrostructureFigure 2 shows the microstructures of carburized SNCM

220 specimens with and without cold treatment, followedby HVOF coating process. The typical microstructure, lathmartensite, of the quenched and tempered SNCM 220

substrate (core) is shown in Fig. 2(a). In Fig. 2(b), thecarburized case of the specimen (220Y) without coldtreatment exhibits a large amount of retained austenite in atypical high-carbon tempered martensitic matrix. Figures 2(c)and 2(d) depict the microstructures of cold treated SNCM220 specimens (220SY, 220CY) at 188K and 153K,respectively. After cold treatment for 1 h at 188K and153K, the retained austenite decreased dramatically, leavingonly scattered retained austenite in the martensitic matrix asshown in Fig. 2(c) and 2(d). In addition, WC/Co coatings ofthe specimens were developed to a thickness of 10­20 µm.

Figure 3 shows the morphology of the WC/Co coatinglayer by using a scanning electron microscope. As shown inFig. 3, WC/Co coating layer exhibited low porosity and

Table 1 Chemical compositions of specimens (mass%).

C Si Mn P S Ni Cr Mo

SNCM 220 0.215 0.303 0.858 0.017 0.013 0.629 0.549 0.197

Table 2 Nomenclature of specimens.

notation processing

220N-Z N: Non-spraying

220Y-Z Y: Sprayed

220SN-Z S: 188K subzero treated

220SY-Z C: 153K cryogenic treated

220CN-Z Z: Hardness of counter roller (6-60HRC; 4-42HRC)

220CY-Z

Fig. 1 The schematic diagram of the wear tester.

(b)(a)

(c) (d)

Fig. 2 Cross-sectional microstructures of specimens at given conditions:(a) core, (b) 220Y, (c) 220SY and (d) 220CY.

L.-H. Chiu, S.-H. Yeh, B.-R. Chen and H. Chang334

uniform WC cuboids distribution with the coating layerroughness (Ra) 3.27 µm, which is in agreement with theobservation by Wang et al.10) using coarse WC particles.

3.2 Microhardness measurementMicrohardness measurements were carried out to reveal

the cross-sectional hardness across the sprayed coating layerand the carburized matrix. The carburized SNCM 220specimen hardness profiles at given conditions are shownin Fig. 4. The microhardness of the carburized case withoutcold treatment reaches 678HV and the effective case depth(ECD) based on the 550HV hardness point is measuredabout 0.5mm. For carburized SNCM 220 specimen (220N)without cold treatment, microhardness profile indicates asurface hardness value of 600HV gradually increasing to678HV at 0.3mm inward into the substrate, followed byprogressively decreasing to the core hardness value of430 « 5HV. This phenomenon can be attributed to theretained austenite softening effect. With cold treatments, thesurface microhardness values were increased significantly to742HVand 747HV with the treatment temperatures at 188Kand 153K, respectively. As can be seen for both hardnessprofiles, the hardness values were progressively decreased tothe core hardness (430 « 5HV) due to the retained austenitetransformation.

3.3 X-ray diffraction examinationsThe X-ray diffraction (XRD) patterns of SNCM 220

specimens are shown in Fig. 5. The prominent presenceof retained austenite peaks in the XRD profiles of 220Nspecimens without cold treatment and their indistinctappearance in the XRD profiles of 220SN and 220CNspecimens with cold treatment assist to compare the amountsof retained austenite in these specimens. The average volumefraction of retained austenite in 220SN specimens signifi-cantly decreases to 7.5 vol% compared to 12.7 vol% retainedaustenite in 220N specimens. The retained austenite in220CN specimen subjected to 153K cryogenic treatmentfurther decreased to 4.4 vol%. These results suggest thatsubzero treatment effectively converts the retained austenitein steel specimens into martensite in accordance with the coldtreatment temperatures.

HVOF process differs from conventional thermal sprayingby drastically increasing flame gas velocity. WC and Coparticles strike on the substrate surface with very high kineticenergy. The particles are not fully molten as the formingof high quality HVOF coatings. Figure 6 shows the XRDpattern of the WC/Co coating layer on carburized SNCM220 specimen. The WC, Co, and small portion of W2C XRDpeaks appear in Fig. 6. This observation is in excellentagreement with the results reported by Wang et al.,10) usingvarious WC mixed powder materials. According to EPMAquantitative analysis, the Co content is about 13.9mass%,indicating that the chemical composition of the WC/Cocoating is similar to the bulk WC-12Co powder used inHVOF process.

3.4 Wear behaviorTo simulate the wear conditions of steel belt pulley used in

an electric nail gun, two types of counter-roller with 60 HRCand 42 HRC hardness values were selected. Figure 7 showsthe cumulative wear mass losses of SNCM 220 specimensagainst 60 HRC counter roller from 3 to 12 h. CarburizedSNCM 220 specimens without cold treatment (220N-6)exhibit the highest cumulative mass loss of 37mg after12 h wear test. The cryogenic treated specimens (220CN-6)exhibit great improvement with cumulative mass loss of20mg due to the increasing hardness and reduction inretained austenite in the carburized case. On the other hand,

Fig. 3 Morphology of WC/Co coated surface.

0.0 0.5 1.0 1.5 2.0

400

450

500

550

600

650

700

750

800

Har

dnes

s, H

V0.

3

Distance from surface, d/mm

Carburized Sub-zero Cryogenic

Fig. 4 Microhardness profiles of SNCM 220 specimens at givenconditions.

Fig. 5 XRD patterns of SNCM 220 specimens at given conditions.

Carbide Spray Coating Influence on Wear Behavior of Carburized Steel against Two Counter-Rollers 335

the cumulative wear mass losses of specimens with theHVOF sprayed coating (220Y-6, 220SY-6 and 220CY-6)were greatly decreased to about 5mg.

Figure 8 indicates the cumulative wear mass losses ofcarburized SNCM 220 specimens tested using 42 HRCcounter roller. Distinct differences were clearly observedbetween HVOF sprayed and unsprayed specimens. Thecumulative wear mass losses of 220N-4, 220SN-4 and220CN-4 specimens with or without cold treatment were183mg, 172mg and 177mg, respectively. Obviously, themass cumulative wear mass losses of carburized SNCM 220specimens tested using 42 HRC counter roller is much largerthan those of specimens tested using 60 HRC counter roller.Despite that, the cumulative wear mass losses of specimenswith the HVOF sprayed coating (220SY-4 and 220CY-4)were also increased significantly to 20mg after 12 h wear test.Particularly, as can be seen in Fig. 8, the cumulative wearmass loss (about 38mg) of 220Y-4 specimen was larger thanthose (about 20mg) of 220SY-4 and 220CY-4 specimensafter 12 h wear test. The wear morphologies of 220Y-4specimen as shown in Fig. 12(c) depicted that the worndepths of 220Y-4 specimen were larger than 220CY-4 coldtreated specimens (Fig. 12(d)). Thus, the cold treatedcarburized case plays an important role in decreasing wearmass loss after 12 h wear test.

With HVOF sprayed coating on cryogenic treatedcarburized SNCM 220 specimens, the wear test results showsignificant wear resistance improvement. The microstructureand morphology of the evaluated coatings (as shown in thefollowing section), as well as the obtained WC/Co coatingmicrohardness values (1209HV), suggested adhesive wearbehavior for HVOF sprayed SNCM 220 steels.

Figure 9 shows the cumulative mass loss profile as thefunction of substrate surface hardness after 12 h wear test.SNCM 220 specimens without carburizing were quenchedand tempered to a hardness value of 430 « 5HV equivalentto 43 HRC representing the core hardness in wear tests. InFig. 9(a), the cumulative mass loss of uncarburized SNCM220 specimen against 42 HRC counter roller after 12 h weartest reaches 202mg, compared to 107mg against 60 HRCcounter roller. As the surface hardness of carburized SNCM220 specimen (220N) reaches 600HV (60 HRC), thecumulative mass losses of 220N-4 and uncarburized SNCM220 specimens exhibited very similar result against 42 HRCcounter roller. However, the cumulative mass loss of 220N-4against 60 HRC counter roller was significantly reduced toabout 40mg. As shown in Fig. 9(b), with HVOF sprayedcoating on either cold treated carburized SNCM 220 oruncarburized SNCM 220 specimen, the wear test resultshows significant improvement in wear resistance. Overall,the results shown in Fig. 9 indicated higher cumulative masslosses against 42 HRC counter rollers.

In Fig. 6, 8 and 9, the obtained patterns for the coatingspecimens in study can be verified with an average variationof less than 5%. The results shown in Fig. 7 to 9 infer that:(1) Due to the reduction of retained austenite in the matrix,

uncoated specimens against 60 HRC counter roller after12 h wear test exhibit decreasing cumulative masslosses as the surface hardness increased (Fig. 9(a)).

(2) With the WC/Co coating applied, all test specimensagainst 60 HRC counter roller after 12 h wear testexhibit comparable wear behavior, irrespective of thespecimen surface hardness (Fig. 9(b)).

(3) With higher surface hardness, the cumulative mass lossof uncoated specimens against 60 HRC counter rollerafter 12 h wear test decreased as shown in Fig. 9(a). Incontrast, the specimens against 42 HRC counter rollerexhibit markedly higher mass losses (Figs. 7 to 9).

Fig. 6 XRD patterns of HVOF sprayed coating.

0.00

0.01

0.02

0.03

0.04

0.05

Cum

ulat

ive

Mas

s L

oss,

M/g

Test Time, t/h

220N-6 220SN-6 220CN-6 220Y-6 220SY-6 220CY-6

3 6 9 12

Fig. 7 Cumulative mass loss of SNCM 220 specimens at given conditions.

0 3 6 9 120.00

0.04

0.08

0.12

0.16

0.20

Cum

ulat

ive

Mas

s L

oss,

M/g

Test Time, t/h

220N-4 220SN-4 220CN-4 220Y-4 220SY-4 220CY-4

Fig. 8 Cumulative mass loss of SNCM 220 specimens at given conditions.

L.-H. Chiu, S.-H. Yeh, B.-R. Chen and H. Chang336

(4) The wear resistances of WC/Co coating specimensafter 12 h wear tests (Figs. 7 to 8) were substantiallysuperior to uncoated specimens. Thus, WC/Co coatingsprovide substantial protection against the wear con-ditions.

3.5 Surface roughnessFigure 10 indicates the SNCM 220 specimen surface

roughness measurement after 12 h wear test. All uncoatedSNCM 220 specimens were ground to the initial surfaceroughness of 0.25 µm using 1000-grit sand paper before thewear tests. In the case of uncoated specimens, after 3 h weartest, the roughness increased to about 0.5 µm against 60 HRCcounter roller. With prolonging test time, the surfaceroughness steadily increased to 0.7 µm. In the case of WC/Co coated specimens, the initial roughness (2.7­3.5 µm)reduced to 0.7­1.0 µm, comparable to the uncoated speci-mens. The results in the surface roughness of worn specimensagainst 42 HRC counter roller had the similar trends against60 HRC counter roller as shown in Fig. 10(b). It is interestingto note that the magnitude of the roughness of the abradedsurface was not strongly affected by the hardness of thecounter rollers used in the wear test. It can be concluded that,after 12 h wear test, the sprayed coating has been abradedaway and the roughness of the abraded surface is consistentfor uncoated and WC/Co coated specimens. Thus, the wearbehavior is dominated by the interaction of abraded surface

condition and the nature of the counter rollers used in thewear test.

3.6 Wear trackThe wear tracks on the specimen surfaces were examined

using a scanning electron microscope (SEM) to document theabraded specimen surface morphology. Figure 11 providesSEM micrographs of SNCM 220 specimen abraded surfacesagainst 60 HRC counter roller after 12 h wear test. InFig. 11(a), the abraded surface of the 220N-6 specimenwithout cold treatment reveals grooves and scratches withslight adhesive phenomenon. In Fig. 11(b), the abrasion ofcryogenic treated specimen (220CN-6) depicted the removalof the substrate material left with light grooves on top of thesurface. The white colored area was identified as oxides byEDX analysis. The fact that oxides existed on the abradedsurface during wear test under room temperature leads tothe conclusion that abrasive and corrosion wear are bothresponsible for the observed wear behavior. In Fig. 11(c),the abraded HVOF spraying coated surface of SNCM 220specimen (220CY-6) revealed a uniform plastic deformationand certain amount of adhesive behavior. As HVOF coatingabraded, abrasion appears to occur mainly by the pull-out ofthe WC cuboids. After 12 h wear test, EDX analysis did notdetect W and Co signals on the abraded surfaces, indicatingthat the WC/Co coating layer was completely removed. SEM

0.00

0.04

0.08

0.12

0.16

0.20

0.24

0.28

Cum

ulat

ive

Mas

s L

oss,

M/g

Hardness of substrate, HV0.3

Counter roller Hardness 42HRC Counter roller Hardness 60HRC(a)

400 450 500 550 600 650 700 750

400 450 500 550 600 650 700 7500.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

Counter roller Hardness 42HRC Counter roller Hardness 60HRC

Cum

ulat

ive

Mas

s L

oss,

M/g

Hardness of substrate, HV0.3

(b)

Fig. 9 Cumulative mass loss profile as the function of substrate hardness,(a) uncoated, (b) coated specimen.

0

1

2

3

4

Surf

ace

Rou

ghne

ss, R

a/µm

Test Time, t/h

220N-6 220SN-6 220CN-6 220Y-6 220SY-6 220CY-6

0 3 6 9 12

0 3 6 9 120.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Surf

ace

Rou

ghne

ss, R

a/µ m

Test Time, t/h

220N-4 220SN-4 220CN-4 220Y-4 220SY-4 220CY-4

(b)

(a)

Fig. 10 Surface roughness of SNCM 220 specimens at given conditionsagainst (a) 60 HRC counter roller, (b) counter roller of 42 HRC.

Carbide Spray Coating Influence on Wear Behavior of Carburized Steel against Two Counter-Rollers 337

micrographs of the abraded surfaces exhibit deep grooves andlarge scratches after 12 h wear test.

During the examination of the abraded surfaces of SNCM220 specimens against 42 HRC counter roller in Fig. 12(a),the abraded surface of the 220N-4 specimen without coldtreatment reveals extensive grooves and scratches withadhesive phenomenon. The worn features of 220CN-4specimen in Fig. 12(b) are consistent with large amount ofplastic deformation with high abrasive and adhesive wear, asobserved in general wear conditions in hardened case steels.In addition, the specimens pressed against 42 HRC counterroller result in more extensive damage to the 220CY-4specimen surfaces (Fig. 12(d)), due to the plough effects ofWC cuboids and surface plastic deformation induced by the42 HRC counter roller.

The worn surface of SNCM 220 specimens against 42HRC counter roller after 12 h wear test exhibits deep andwide grooves and scratch marks, compared to the uniformand less severe damage on the worn surface from 60 HRCcounter roller. The surface roughness of 60 HRC and 42 HRCcounter rollers after 12 h wear tests were measured as 0.47and 2.17 µm, respectively. Clearly, specimens against 42HRC counter roller are suffered a great deal of abrasive andadhesive wear attacks accompanied with large damage to the42 HRC counter roller as well. The observed wear resistancesof specimens against 42 HRC counter roller were signifi-cantly decreased as shown in Fig. 9.

SNCM 220 specimens against 42 HRC counter roller after12 h wear test has shown large plastic deformation and greatdeal of adhesive abrasion wear on the surfaces. However,SNCM 220 specimens against 60 HRC counter roller after12 h wear test has shown less damage on the abraded

surfaces. In Fig. 8, coated specimens with cold treatment(220SY-4, 220CY-4) against 42 HRC counter roller after 12 hwear test exhibited cumulative mass loss about 20mg. Incomparison, the specimen (220Y-4) without cold treatmentexhibited cumulative mass loss about 38mg. Thus, coldtreatment improved the wear resistance of SNCM 220 steelswith or without coatings.

To enhance the wear resistance, it has shown that hardnessof SNCM 220 specimen and counter roller must becompatible. Softer counter roller induces plastic deformationon the specimen surfaces, eventually causing large cumu-lative mass losses on all SNCM 220 specimens.

4. Conclusions

WC/Co coatings at 15 « 5µm thicknesses were depositedonto the steel specimens using high velocity oxy-fuel(HVOF) process. The experimental result indicates that themicrohardness of the WC/Co coating reaches 1209HV. Aseries of wear tests was conducted under a 95.9N normalload at 180 rpm on a dry abrasive block-on-roller wear tester.From the 12 h wear test results, the cumulative mass loss ofcryogenic treated 220CN-6 specimen decrease from 37mg of220N-6 specimen to 20mg. In contrast, the cumulative massloss of carbide coated 220CNY-6 specimen using HVOFspraying process decreased to 4mg. The cumulative massloss improvement with HVOF spaying coatings is significantand in this sense a good performance of WC-Co basedcoatings in abrasive wear applications can be expected.

In wear tests, the nature of the counter roller affects thewear characteristics and the specimen wear resistance. Theresults indicate that using 42 HRC counter roller showed a

(a) (b)

(c)

Fig. 11 The SEM micrographs of SNCM 220 specimens after 12 h wear test (a) 220N-6, (b) 220CN-6, (c) 220CY-6.

L.-H. Chiu, S.-H. Yeh, B.-R. Chen and H. Chang338

deleterious influence on the wear resistance. More interest-ingly, the results also indicate that large plastic deformationand adhesive wear were observed on all specimens against 42HRC counter roller. From the SEM micrograph examina-tions, the worn surfaces exhibit severe abrasive and adhesivewear attacks, resulting in inferior wear resistance perform-ance during the wear tests. To enhance the wear resistance,the hardness of SNCM 220 specimen and the counter rollermust be compatible.

Acknowledgement

Financial support of this research by National ScienceCouncil, Republic of China, under the grant NSC100-2221-E-036-011 is gratefully acknowledged.

REFERENCES

1) A. Bensely, A. Prabhakaran, D. Mohan Lal, G. Nagarajan, M. Izcilerand M. Tabur: Cryogenics 45 (2005) 747­754.

2) H. J. Kim and Y. G. Kweon: Wear 193 (1996) 8­15.

3) B. S. Saini and V. K. Gupta: Surf. Coat. Technol. 205 (2010) 511­518.4) M. Koneshlou, K. Meshinchi Asl and F. Khomamizadeh: Cryogenics

51 (2011) 55­61.5) H. X. Chi, D. S. Ma, Q. L. Yong, L. Z. Wu, Z. P. Zhang and Y. W.

Wang: J. Iron Steel Res. 17 (2010) 43­46.6) D. Das, R. Sarkar, A. K. Dutta and K. K. Ray: Mater. Sci. Eng. A 528

(2010) 589­603.7) D. Das, K. K. Ray and A. K. Dutta: Wear 267 (2009) 1361­1370.8) L. H. Chiu, Y. M. Lin, S. H. Yeh and H. Chang: Adv. Mat. Res. 154­

155 (2011) 1143­1151.9) V. Firouzdor, E. Nejati and F. Khomamizadeh: J. Mater. Process.

Technol. 206 (2008) 467­472.10) Q. Wang, Z. H. Chen and Z. X. Ding: Tribol. Int. 42 (2009) 1046­1051.11) S. Hazra, K. Sabiruddin and P. P. Bandyopadhyay: Surf. Eng. 28 (2012)

37­43.12) T. Sudaprasert, P. H. Shipway and D. G. McCartney: Wear 255 (2003)

943­949.13) Q. Q. Yang, T. Senda and A. Ohmori: Wear 254 (2003) 23­34.14) Y. Y. Santana, J. G. La Barbera-Sosa, A. Bencomo, J. Lesage, D.

Chicot, E. Bemporad, E. S. Puchi-Cabrera and M. H. Staia: Surf. Eng.28 (2012) 237­243.

15) S. Zhao, X. Song, C. Wei, L. Zhang, X. Liu and J. Zhang: J. Ref. Met.Hard Mat. 27 (2009) 1014­1018.

16) ASTM E975-00: ASTM Book of Standards, V 03.01, PA, USA,(2004).

(a) (b)

(c) (d)

Fig. 12 The SEM micrographs of SNCM 220 specimens after 12 h wear test (a) 220N-4, (b) 220CN-4, (c) 220Y-4, (d) 220CY-4.

Carbide Spray Coating Influence on Wear Behavior of Carburized Steel against Two Counter-Rollers 339