A

hBdcafiT©

K

1

lhwrthtcooa

osMt

0d

Wear 263 (2007) 234–239

Short communication

The friction and wear of various hard-face claddings for deep-hole drilling

John Truhan a,∗, Ravi Menon b, Frank LeClaire b, Jack Wallin b, Jun Qu c, Peter Blau c

a University of Tennessee, Knoxville, TN, USAb Stoody Company, Bowling Green, KY, USA

c Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA

Received 22 August 2006; received in revised form 29 January 2007; accepted 30 January 2007Available online 19 March 2007

bstract

Hard-face claddings are used for banding drill shafts that rotate against well casings while lubricated by drilling mud. This tribosystem shouldave the lowest friction possible in order to minimize drilling power requirements, and the lowest total system wear to maximize component life.locks representing a variety of hard-face claddings were slid against rotating rings of AISI 4140 casing material and lubricated by simulatedrilling mud that consisted of a slurry of silica sand, clay, and water. The cladding specimens included currently used alloys and several candidateompositions. There was an excellent correlation between the friction coefficient and the wear, by weight loss, of both the cladding and the casing

lloys. There was also a good direct correlation between the wear of the cladding and the wear of the casing. Claddings with finer grain sizes andner, more uniformly distributed hard carbides had higher hardness and produced lower wear on both the cladding and the casing counter-face.he complex mechanisms involved with three-body wear and friction in interfaces lubricated by slurries present a challenge for further study.2007 Elsevier B.V. All rights reserved.

aswimuautrwrv

eb

eywords: Deep-hole drilling; Slurry; Abrasion; Hard-face cladding

. Introduction

Deep-hole drilling for mining applications presents a chal-enge in the choice of drilling materials due to the extremelyarsh operating environment in which they must perform. Lowear is obviously desirable to increase shaft and casing life and

educe maintenance while low friction is desirable to reducehe energy needed for drilling. Extensive development effortsave been undertaken on hard-faced claddings for drill shaftso reduce wear and friction. However, any evaluation of theladding alloys must also include an evaluation of the responsef the counter-face, i.e., the well casing. The optimum choicef materials would be the combination producing the least wearnd friction for the tribosystem.

There are several industry-recognized tests for the evaluationf cladding and casing materials lubricated by a drilling “mud”

lurry, but each has advantages and disadvantages. The DEA-42

aurer Test is a proprietary test for casing wear and requireshe use of large specimens. This test is difficult to perform,

∗ Corresponding author.E-mail address: Truhan John J@cat.com (J. Truhan).

fbftwob

043-1648/$ – see front matter © 2007 Elsevier B.V. All rights reserved.oi:10.1016/j.wear.2007.01.046

nd consequently, is relatively expensive. The ASTM G65 dry-and/rubber wheel test [1] and the ASTM G105 wet sand/rubberheel test [2] for abrasion resistance are less expensive and eas-

er to carry out, but they do not allow for the influence of aetal counter-face. In previous work [3], a pin-on-disk test was

sed to measure the friction between various cladding alloysnd AISI 4140 counter-face representative of casing materialnder slurry-lubricated conditions. Although a relatively simpleest to conduct, the degree of wear could not be measured accu-ately due to the production of a shallow, diffuse wear scar. Thisas primarily due to the relatively small area of contact and the

elatively large particles of silica in the slurry creating rapidlyarying interfacial conditions.

While, there have been numerous publications on slurryrosion and the effects of drilling mud (e.g., [4–6]), little haseen published concerning the effects of abrasive slurries onriction. The current study expands on the previous work [3]y reporting a new block-on-ring procedure that enables bothriction and wear measurements. Conditions were selected so

hat the tests could be run in a short time but produce enoughear to use weight loss as an unambiguous measure. Thebjectives of this study were: (1) to develop a rapid, inexpensiveench test which correlates with field experience and other

J. Truhan et al. / Wear 263 (2007) 234–239 235

Fls

imccw

2

a5

Table 1Summary of experimental conditions

Rotational speed 300 rpmTangential speed 94 cm/secRing alloy and hardness AISI 4140, 217 BHNTest time 2.00 minSliding distance 112.8 mApplied load 90.5 N

Table 2Composition of slurry (mud)

Bentonite (Quik GelTM) 31.8 gSW

vrwuipistTtbat

ibdsw

TC

B

T11

1

1

1111

ig. 1. (a) Overall view of the block-on-ring test configuration showing the staticoad in place. (b) Close-up view of the block (cladding), ring (casing), and thelurry reservoir below the ring.

ndustry-recognized tests, (2) to evaluate drill shaft claddingaterials for optimum friction and wear behavior against well

asing materials lubricated by a drilling mud slurry, and (3) toompare the wear resistance of current commercial claddingsith that of advanced candidate claddings.

. Experimental procedure and materials

The block-on-ring tests were carried out using commerciallyvailable equipment shown in Fig. 1(a and b) (Plint Model TE-3, Phoenix Tribology Ltd., UK). Fig. 1(a) shows an overall

moas

able 3omposition and hardness of hard-facing claddings

lock material Generic description Hardness

J4140 Tool joint material 285 BHNP Martensitic tool steel 51 HRC2P Martensitic titanium/niobium carbide 40 HRC

3P Martensitic niobium, molybdenumcarbide

64 HRC

4P Martensitic niobium, molybdenum,tungsten carbide

66 HRC

5P Martensitic tool steel 41 HRC7P Semi-austenitic stainless steel 53 HRC8P Martensitic niobium, boron tool steel 58 HRC9P Martensitic titanium carbide 55 HRC

a Conversion of BHN to HRC based on ASTM E140.

ilica sand (Clemtex #5) 144.2 gater 500 ml

iew of the apparatus with the dead-weight loading visible on theight. Fig. 1(b) shows the mounted test coupons. The 12.7 mm-ide slider block with the hard-face cladding is mounted on thepper holder and the rotating ring, representing the casing alloy,s mounted below it. A reservoir contains the slurry. The lowerart of the ring picks up the slurry as it rotates and carries it to thenterface. A metal shield, not shown, prevents the slurry fromplashing out. Friction force is measured with a load cell andhe data are collected using a computer data acquisition system.he test parameters are summarized in Table 1. The load and

est duration were selected to produce enough wear on both thelock and ring to use weight loss as the wear metric. Since thevailability of sample materials was limited, only two replicateests were allowed for each cladding.

The slurry was a simulated drilling mud, whose compositions given in Table 2. In order to get the most uniform distri-ution, the clay was first mixed in the water until thoroughlyispersed and then the silica was slowly added with continuedtirring. Since settling was inevitable between tests, the slurryas agitated just prior to filling the reservoir.The 60 mm-diameter rings were used to represent the casing

aterial and were AISI 4140 alloy steel tempered to a hardnessf 217 BHN. The block claddings represent both currently usedlloys and several developmental ones. A block of 4140 steelimilar to the ring was also tested as a reference couple. Since

Block HRCrelative to ring

Nominal composition (wt%)

(30 HRCa) 1.0 0.4 C, 1.0 Cr, 0.2 Mo1.7 0.5 C, 5 Cr, 0.2 Mo1.3 0.8 C, 7.5 Cr, 0.6 Mo, 2.5 Nb,

0.9 Ti2.1 1.0 C, 8 Cr, 0.7 Mo, 3 Nb

2.2 1.0 C, 3.5 Cr, 4 Mo, 3.5 W, 2Nb

1.4 0.4 C, 5 Cr, 0.5 Mo, 0.3 V1.8 0.1 C, 20 Cr, 3 Nb, 3 B1.9 0.6 C, 1 Ni, 3 B, 3 Nb1.8 1.0 C, 5 Cr, 3 Ti

236 J. Truhan et al. / Wear 263 (2007) 234–239

F unifo1

ttt

sa

af

ig. 2. Cladding microstructures representative of the two broad categories of7P.

here is directionality to the microstructure of the cladding dueo the deposition process, care was taken to orient the block so

he deposition direction matched that for service conditions.

The nominal compositions of the various claddings tested areummarized in Table 3. Alloys identified as 1P, 15P, 17P, 18P,nd 19P are current cladding materials. The remaining cladding

cw1a

rmity: (a) Alloy 1P, (b) Alloy 19P, (c) Alloy 12P, (d) Alloy 14P, and (e) Alloy

lloys were developed by the Stoody Company for wear per-ormance as well as ease of application. The majority of the

ladding alloys, except Alloy 17P, have in a martensitic matrixith or without dispersed secondary carbides and borides. Alloy7P is the only stainless steel in the test program and consists ofdispersion of chromium borides in a semi-austenitic matrix.

ear 263 (2007) 234–239 237

Ffadbd(aissscts

3

rotaroctlwmai

hFtoctsw

Fig. 4. Block (cladding) and ring (casing) wear results stacked to show totalsystem wear.

F(

bssad

J. Truhan et al. / W

Representative microstructures of the test alloys are shown inig. 2(a–e). Alloy 1P (Fig. 2(a)) is a martensitic tool steel hard-acing deposit. In addition to martensite there is some retainedustenite. Alloy 19P (Fig. 2(b)) has a similar matrix along withispersed TiC. Alloy 12P (Fig. 2(c)) is similar to Alloy 19Put some of the Ti has been replaced with Nb and Mo to pro-uce better wear performance. In the developmental Alloy 14PFig. 2(d)), the Ti has been completely replaced with Nb, Mo,nd W. Although this replacement results in a small increasen the total system wear, the applicability of the hard-facing isignificantly improved due to the reduction of Ti in the wire con-umable used to deposit it. Alloy 17P (Fig. 2(e)) was the onlytainless steel hard-facing tested. Its microstructure shows aci-ular chromium borides in a semi-austenitic matrix. In contrasto the alloys shown in Fig. 2(b–d), there is no finely dispersedecondary micro-constituent.

. Results and discussion

Friction and wear results from this investigation are summa-ized in Fig. 3. The highest friction and wear, not surprisingly,ccur for the reference couple: self-mated 4140. As expected,he amount of wear for the clad blocks was reduced by almostn order of magnitude compared to the self-mated couple. Weareductions for the rings were not as dramatic, with reductionsn the order of 20–40%. The friction coefficient for all claddingombinations exhibited little variation and is only slightly lowerhan that for the self-mated couple. Frictional behavior wasikely to be controlled mainly by the properties of the slurryith its substantial amount of entrained silica dust. Harderaterials probably allowed less silica particulate indentation

nd therefore, slightly reduced the frictional drag in thenterface.

As stated previously, it is important that the wear-resistantard-face cladding should not accelerate the wear of the casing.ig. 4 shows the sum of the wear on both specimens as the

otal system wear for the various cladding combinations. Mostf the variation in total system wear is due to the ring wear

ontribution, demonstrating the importance of not focusing onhe cladding wear exclusively. Certain combinations performubstantially better than others. The lowest total tribosystemear was achieved by couples using the 12P and 19P claddings.

Fig. 3. Summary of friction and wear results for the various claddings.

ara

F

ig. 5. Relationship between the friction coefficient and wear for both the blockcladding) and ring (casing).

As indicated in Fig. 5, there was a distinct relationshipetween friction and wear, and that was irrespective of compo-ition or microstructure, implying that the hard-face claddingsliding against the slurry-lubricated casing material behaved inmechanistically similar manner. The more energy available too frictional work, the more material was abrasively removed.

Fig. 6 data indicate an approximate trend between block wear

nd the ring wear. Lower block wear tended to accompany lowering wear. A possible explanation may be found in the highlybrasive nature of the slurry. The silica dust in the slurry is much

ig. 6. Relationship between block (cladding) wear and ring (casing) wear.

238 J. Truhan et al. / Wear 263 (2007) 234–239

and

hbadqtsrTatacbtebroast

htc

4fni

imstcreecda

mcdmTF

Fig. 7. Wear scars for the (a) block

arder than either surface and therefore, can cause wear in both,ut the relative amount may differ. When a harder material rubsgainst a softer one, there is always the question as to whategree the harder material causes wear in the softer. From auasi-static point of view, the degree to which a hard particlerapped between two softer surfaces will penetrate either of thoseurfaces should correspond directly to their relative hardness (theatios of the HRC of the block relative to the ring are given inable 3). However, that quasi-static argument does not take intoccount the fact that in slurry wear, the hard particles are passinghrough the interface entrained within a viscous fluid, tumbling,nd cutting. Plowing or cutting occurs only when sufficient loadan be transferred to a particle or agglomerate that happens toe aligned advantageously to produce a nick or scratch. If one ofhe surfaces is so ductile that hard particles become momentarilymbedded, there could be two-body abrasion as well as three-ody abrasion occurring. Post-test optical examination did noteveal any apparent silica embedded into the 4140 rings, butxidation of the test specimens during the time between testingnd observation obscured the finer wear scar features. Additionaltudies by electron microscopy would have been desirable, buthe scope of the project did not allow them.

There were no evident correlations between the cladding

ardness and either the friction coefficient, block weight loss, orhe ring weight loss. This result is somewhat surprising since theladding hardness for the various materials ranges from about

fcd

Fig. 8. Wear scars for the 14P cladding on

(b) ring for self-mated 4140 steel.

0–66 HRC, a wide variation. Although the fundamental reasonsor these results remain unclear, it is evident that cladding hard-ess alone was not a good predictor of wear or friction behaviorn this particular tribosystem.

It is interesting to note that the friction coefficients measuredn this study are roughly a factor of two higher than previously

easured using a pin-on-disk test [3]. It is likely that the higherurface area and converging linear contact of the block-on-ringests allows for a more representative slurry composition to beonfined within the interface. The small surface area of theounded pin tip would not be expected to trap much silica dust,specially the larger particles. Support for the lack of particlentrainment in the pin-on-disk tests can be found in their frictionoefficients. Friction coefficients for slurry-lubricated pin-on-isk tests were comparable to those run with water lubricationlone (0.33 compared to 0.35).

There appears to be a connection between the claddingicrostructure and tribological performance. In general,

laddings with a finer, more uniform grain size, and a uniformispersion of carbides had better friction and wear perfor-ance than claddings with more heterogeneous microstructures.his can be seen by comparing the microstructures in Fig. 2.ig. 2(b–d) represents the claddings that had better overall per-

ormance. These include both developmental claddings and oneommercial one. Their microstructures are similar despite theirifferences in hardness due to different carbide types. In con-

the (a) block and (b) 4140 steel ring.

ear 26

tcirrp

bmcBsws

flcHccirhfs

4

•

•

•

•

•

•

•

A

fdTNU0

R

[

[

[

[

[5] Y. Peysson, Solid/liquid dispersions in drilling and production, Oil Gas Sci.

J. Truhan et al. / W

rast, cladding alloys represented in Fig. 2(a and e) displayoarser, more heterogeneous microstructures, with correspond-ngly poorer friction and wear performance. Although theseesults are not unexpected, they are in contrast with previousesults [3] and that demonstrates the difficulty with using thein-on-disk test with slurry-lubrication.

Figs. 7 and 8 show the appearance of the typical wear scars onoth the block and ring for high and low wear couples. The self-ated 4140 steel couple in Fig. 7 displays severe abrasive wear,

onsistent with the high wear measured for that combination.y contrast, the morphology of the wear scar for a clad block

howing low friction and wear (14P in this case) shows abrasiveear as well, but with much finer parallel scoring and a smaller

car area, particularly on the block side.Understanding the scope of the complex interaction between

uid dynamics, instantaneous mechanical contact, and fluidhemistry goes well beyond the scope of this communication.owever, the results of this work suggest that while the slurry

haracteristics have a major influence on sliding friction betweenladding and casing materials, the selection of materials cannfluence it as well, and that the total tribosystem wear can beeduced by judicious selection of material compositions. It isoped that these results will provide experimental support forurther systematic studies on the interactions of materials andlurries in drilling environments.

. Conclusions

The block-on-ring test configuration, which is relatively sim-ple to use, can be helpful in evaluating both the friction andthe wear of drill shaft cladding alloys against a casing alloyin slurry-lubricated conditions.Block-on-ring results produced more quantitative wear mea-surements than were possible using pin-on-disk tests on

similar materials.There was a very good correlation between friction and wearof both the cladding (block) and the casing (ring) materials inslurry-lubricated conditions.

[

3 (2007) 234–239 239

There was a good correlation between the cladding wear andcasing wear.There was no apparent correlation of the cladding hardnessalone with either cladding friction or wear, although hardercladdings produced less casing material wear.A fine, uniform cladding microstructure produced lower fric-tion and wear than coarser microstructures.The newer developmental cladding alloys generally per-formed better than most of the current commercially availablecladdings.

cknowledgements

This research was sponsored by the Assistant Secretaryor Energy Efficiency and Renewable Energy, Office of Free-omCAR and Vehicle Technologies, as part of the Highemperature Materials Laboratory User Program, Oak Ridgeational Laboratory, managed by UT-Battelle, LLC, for the.S. Department of Energy under contract number DE-AC05-0OR22725.

eferences

1] ASTM G 65-04, Standard Test Method for Measuring Abrasion Using theDry Sand/Rubber Wheel Apparatus, Annual Book of Standards, vol. 03.02,ASTM International, West Conshohocken, Pennsylvania.

2] ASTM G 105-02, Standard Test Method for Conducting Wet Sand/RubberWheel Abrasion Tests, Annual Book of Standards, vol. 03.02, ASTM Inter-national, West Conshohocken, Pennsylvania.

3] J.J. Truhan, R. Menon, P.J. Blau, The evaluation of various cladding materialsfor down-hole drilling applications using the pin-on-disk test, Wear 259(2005) 1308–1313.

4] M.R. Duignan, S.Y. Lee, RPP-WTP Slurry wear evaluation: literature review,Westinghouse Savannah River Company Report WSRC-TR-2001-00156,2001.

Technol. Rev. IFP 59 (1) (2004) 11–21.6] P. Skalle, K.R. Backe, S.K. Lyomov, L. Kilaas, A.D. Dyrli, J. Sveen,

Microbeads as lubricant in drilling muds using a modified lubricity tester,Society of Petroleum Engineers, Paper SPE 56562, 1999.