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Author's Accepted Manuscript

Effect of cutting conditions on wear perfor -

mance of cryogenically treated tungsten car -

bide inserts in dry turning of stainless steel

Nursel Altan Özbek, Adem i!ek, Mahmut

"#lesin, $nur Özbek

ww w%else&ie r%comlocatetriboint

())* +.-/0123.45//-0

6$)*h tt p*''d7%doi%org'.%../'8%triboint%9.4%:%9;< efer ence* =><)-:,.

>o appear in* >ribology )nternational

<ecei&ed date* 9; April 9.4<e&ised date* 9; =uly 9.4Accepted date* .9 August 9.4

?ite this article as* Nursel Altan Özbek, Adem i!ek, Mahmut "#lesin, $nur

Özbek, Effect of cutting conditions on wear performance of cryogenicallytreated tungsten carbide inserts in dry turning of stainless steel, >ribology)nternational, h t t p*''d7%doi%org'.%../'8%triboint%9.4%:%9;

>his is a (6@ file of an unedited manuscript that has been accepted for

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http://dx.doi.org/10.1016/j.triboint.2015.08.024








.

Effect of cutting conditions on wear performance of cryogenically

treated tungsten carbide inserts in dry turning of stainless steel

Nursel Altan Özbek a, Adem i!ek

b,, Mahmut "#lesin

c, $nur Özbek

d

a Düzce University, Cumayeri Vocational School of Higher Education, Düzce 81!!, "ur#ey

$%&ld&r&m'eyaz&t University, (aculty of Engineering and )atural Sciences, De*artment of +echanical Engineering, n#ara !-!.!, "ur#ey

"el/0!2132341...

(a 5/0!2132341.!. E 6 m a i l/a c ice# 7 y $ u 8e d u 8 t r

c9azi University, (aculty of "echnology, De*artment of +anufacturing Engineering, n#ara !-.!!, "ur#ey

d Düzce University, 9ümüBova Vocational School of Higher Education, Düzce 818.!, "ur #ey

Abstract

)n this study, the effects of cryogenic treatment on tool wear of uncoated tungsten carbide inserts were

in&estigated in the turning of A)+) ./ stainless steel% )t was found that notch wear appeared at low and medium

cutting speeds, while flank wear and crater wear formed at all combinations of the process parameters selected

for turning% )n addition, treated inserts e7hibited superior wear performance to untreated ones% >his can be

attributed to high wear resistance and low thermal conducti&ity of treated inserts% >he results were &erified by

analyses of microstructure and hardness, image processing and 2-ray diffraction%

Keywords: ?ryogenic treatment, >ungsten carbide, >ool wear, Cear r esistance

1.Introduction

>he life of tungsten carbide inserts plays a ma8or role in the producti&ity of machining operations and tooling

costs due to the fact that tungsten carbide 3C?-?o5 is one of the most common cutting tool materials used in

industry% >herefore, these inserts are e7pected to be resistant to the ele&ated temperatures and forces gener ated

during con&entional cutting operations %

>he e7cessi&e temperatures and forces occur in the machining of stainless steels ha&ing hard machinability

characteristics due to high Ni and ?r content% >his case leads to rapid tool wear and failure of tungsten carbide

tools% ?ryogenic treatment is a process employed to enhance the life of cutting tools by means of the micro-

structural changes that occur during treatment% )n cryogenic treatment, samples are sub8ected to gradual cooling

from room temperature to cryogenic temperatures 3up to -.1/ D?5, held for a certain period 3in general, 9; h5,

and then gradually heated back to room temperature% Many studies report that some mechanical and physical

properties of tool materials such as tool steels and cemented carbides impro&e with cryogenic treatment%

@irouzdor et al% in&estigated the effects of cryogenic treatment on tool life and wear resistance in drilling of

carbon steels with M9 ++ drills at higher speeds% E7perimental results showed that tool life of treated and

tempered drills substantially impro&ed 3up to .9/F5% omogeneous distribution of carbides and transformation

of retained austenite into martensite were two reasons of impro&ements in tool life of ++ drills% i!ek et al

mailto:E-mail:[email protected]






studied machinability of A)+) ./ austenitic stainless steel using cryogenically treated and untreated ++ twist

drills% E7perimental results showed that tool life of treated drills impro&ed from .;F to 9.:F% >he

impro&ements were mainly attributed to formation of fine and homogeneous carbide particles and tr ansformation

of retained austenite to martensite% Akhbarizadeh et al% performed a study to in&estigate the effects of cryogenic

treatment on wear beha&iour of A)+) 6/ cold work tool steel% >he results re&ealed that cryogenic treatment

substantially reduced the amount of retained austenite in the microstructure and therefore it impro&ed wear

resistance and hardness of A)+) 6/ tool steel% uang et al% reported that cryogenic treatment significantly

changed the microstructure of M9 tool steel% >he e7periments indicated that wear resistance of the tool steel

impro&ed due to facilitating the carbon clustering after cryogenic treatment and increases in the carbide density

after subseGuent tempering process% Hiu et al% claimed that the hardness and abrasion resistance of ?rMnI high-

chromium cast iron could be impro&ed ob&iously due to the precipitation of carbides, the mar tensite

transformation, and a refined microstructure resulting from cryogenic treatment%Cang et al in&estigated the

effects of deep cryogenic treatment on the microstructure, hardness and abrasion resistance beha&iours of

./?r.Mo.?u cast iron sub8ected to destabilization treatment% >he results showed that the cryogenic treatment

can effecti&ely reduced the retained austenite after destabilization heat treatment, but could not make r etained

austenite transform completely% ?ryogenic treatment can markedly impro&e bulk hardness and abrasion

resistance of the high chromium cast iron% "ill et al% aimed to present the metallurgical and mechanical

characterization of cryogenically treated tungsten carbide 3C?J?o5 in terms of K-phase particles and wear

beha&iour% >hey declared that the hard phase particles of tungsten carbide were refined into their most stable

form &ia the phenomenon of spheroidization after shallow 3-.. D? for .: h5 and deep 3-.1/ D? for : h5

cryogenic treatment% )t was pointed out that cryogenic treatment caused crystal structure changes in both the hard

and soft binder phases of the tungsten carbide material, which may ha&e been responsible for the enhanced

hardness and wear resistance properties along with the precipitation of K phase carbides% Lao reported that the

abrasi&e wear resistance of sintered tungsten carbide inserts had increased after cryogenic treatment% Iryson

claimed that the wear resistance, and hence increase in tool life, of carbide tools was pro&ided by the

impro&ement in the holding strength of the binder after cryogenic treatment% <eddy et al% in&estigated the

machinability of ?;4 steel with untreated and treated 3-.0/ D? for 9; h5 tungsten carbide )+$ (- inserts in

terms of flank wear, main cutting force, and surface finish% )t was determined that cryogenic treatment resulted in

better machinability due to the increase in the thermal conducti&ity of the tungsten carbide% >his resulted in a

decrease in the temperature of the tool tip during the turning process% adi&el and <udramoorthy e7amined the

performance of cryogenically treated and untreated coated carbide inserts in terms of flank wear, power

consumption, and surface roughness in the turning of nodular cast iron% $n the whole, the cryogenically treated

coated carbide inserts e7hibited a better performance than that of the untreated ones% >his outcome was attributed

to the presence of fine K-phase carbide distribution in the cryogenically treated inserts% ong et al% in&estigatedand analyzed the differences in tool performance between cryogenically treated and untreated tool inserts during

the orthogonal turning of steel% >he authors claimed that treated tools performed best when the tool temper atur e

was kept low and that hea&y-duty cutting operations would not benefit when the cutting tool was heated for long

periods% <am8i et al% reported that cryogenically treated tungsten carbide inserts e7hibited superior wear

performance to untreated ones in turning of gray cast iron at all combination of cutting par ameters%



>he present study aimed to elucidate the effects of cryogenic treatment on flank wear, notch wear and cr ater

wear in the turning of A)+) ./ austenitic stainless steel with uncoated cemented carbide inserts% >o achie&e this

goal, a number of turning e7periments were conducted on a ?N? lathe% +canning electron microscope 3+EM5,

2-ray diffraction 32<65 and image processing analyses as well as hardness and wear measurements were carried

out in order to e&aluate the obtained results%

2. Materials and Methods

Austenitic stainless steel 3A)+) ./5 bars of . mm in diameter and 94 mm in length were used as workpiece

materials in the turning e7periments performed on the ?N? lathe% >he cutting parameters were determined

according to the cutting tool manufacturersO recommendations and the e7periments were performed at four

cutting speeds, three feed rates and a constant depth of cut% >he e7perimental conditions are shown in >able .%

Pncoated tungsten carbide inserts recommended by )+?A< for machining of austenitic stainless steels were used

in the wear e7periments% Corldwide usage ratio of uncoated carbide tools within all cutting tools is around .0F %

>herefore, wear performance of uncoated carbide tools with high usage ratio should be enhanced% )n addition,

the effects of cryogenic treatment can be obser&ed on uncoated tools more clearly because they ha&e no a

thermal barrier as a hard coating% ence, uncoated tungsten carbide inserts were cryogenically treated at a

temperature of -.;4 D? for 9; h% After cryogenic treatment, they were tempered at a 9 D? for 9 h% )n order to

clearly e&aluate the performance difference and wear progress of the cemented carbide inserts in terms of tool

wear, the cutting process was periodically stopped and the amount of flank wear and notch wear formed on the

inserts were measured using a digital microscope% >he depth of craters was measured at the end of theturning

e7periments using a Mahr ?onturograph with an accuracy of . Q m and tip radius of 94Q m% >he measurements

of microhardness were performed under a load of 9 g for .4 s using an M +)MA6RP microhardness

tester% >he microhardness was measured si7 times for each specimen and the mean &alue of these

measurements was accepted as the microhardness &alue of that specimen% >he +)MA6RP 2<6-/ de&ice was

used to take 2<6 profiles of the inserts% Cear and microstructure images of the inserts were taken using the

HE$ .;( +EM de&ice% Iefore microstructure images were taken, the surfaces of the specimens were

etched with Mur ak ami solution% )n addition, the amounts of K carbides before and after cryogenic treatment were

determined by image processing 3?leme7 ision Hite5 sof twar e%

Table 1

E7perimental conditions%



Machine tool * >AL+AN >>?/ ?N? latheCorkpiece material * A)+) ./ Austenitic +tainless +teel 3?*%;F, Mn*.%.:F, +i*%;.F, (*%:F,3?hemical composition5 +*%.9F, ?r*./%F, Ni*.%1F, Mo*9%9F, ?u*%;1F5

?utting tool * Pncoated tungsten carbide

+NM" .9;.9 J >@>ool holder * 6+IN<'H 9494 M.9?utting method * $bliGue cutting?utting condition * 6ryeat treatment * ?ryogenic tr eatment?utting speed, c * ., .9, .; and ./ m'min@eed rate, f * %.4, % and %;4 mm'r e&6epth of cut, a * 9%; mm

. E!perimental "esults and #iscussion

21 +icrostructural o$servations

211 +icrostructure analysis

>here are three main phases in the microstructure of C?-?o inserts, namely, the S phase 3C?5, T phase 3?o5,

and K phase 3?oC? and ?o/C/?5% @ig% . shows +EM pictures of the S, T and K phases of the untreated and

treated uncoated inserts% >he K carbides appear as dark gray spots in the microstructure of the carbide inserts%

adi&el and <udramoorthy reported that the cryogenic treatment refined coarser, randomly-distributed K phase

particles into the most stable form% >hese f iner particles along with the larger tungsten carbide particles formed a

denser, more coherent and much tougher matri7% After cryogenic treatment, the fine K carbides impro&ed thehardness and wear resistance without significantly affecting the toughness% $n the other hand, the effects of

cryogenic treatment on S phase grain size of the carbide inserts were noted and in&estigated% Ppon measuring the

size of the particles, it was found that the a&erage grain size was .1%0.4 nm and 9.%;; nm for the untreated and

treated inserts, respecti&ely% <eddy et al% claimed that the cryogenic treatment reduced the chemical degradation

of the cobalt matri7 at higher temperatures% Hower binder contents in tungsten carbide samples increased the

o&erall thermal conducti&ity% An increase in carbide grain size for the cryogenic treated cemented carbides

increased the thermal conducti&ity of cemented carbide% >his effect was attributed to an increase in carbide grain

contiguity and the dominant role of the carbide phase in thermal conduction in tungsten carbide based cemented

carbides%



$ig. 1. Microstructures of C?J?o inserts* a5 untreated, b5 treated%

>he +EM pictures also show some new carbide particles which appeared after the cryogenic treatment and

tempering process% >hus, the cryogenic treatment increased the amount of carbide and homogenously distributed

carbide particles in the microstructure% >o &erify the increases in and the homogenous distribution of the carbide

particles, an image analysing software was employed% >he K carbide zones were coloured red by means of this

software 3@ig% 95% )t was obser&ed from these pictures that the amount of K carbide had significantly increased

after the cryo-tempering process%

)n addition, the numerical results of the image processing are shown in >able 9% >he percentages of carbide for

the untreated and treated inserts were 0%4F and .9%1F, respecti&ely% Iriefly, it was found that the carbides in the

treated inserts had increased by 4%;F in comparison with the untreated ones%

a5 b5

$ig. 2. >he red-colored K carbides in the C?J?o inserts* a5 untreated, b5 tr eated%

Table 2

Amounts of K carbide%K carbide rate 3F5



K carbide count K carbide sum% size 3Q m95

Pntreated 0%4 9499 1;%1>r eated .9%1 ./9%:

Altan Özbek et al% obser&ed some new K-carbide regions and more homogeneous distribution of carbides in the

microstructure of treated tungsten carbide inserts after cryogenic treatment for 9; h% )t was reported in the study

that this case led to significant increases in wear resistance of treated turning inserts% <eddy et al% reported

that, along with critical temperatures, new K carbides were formed in the microstructure of ( tungsten

carbide inserts% "ill et al% determined that S phase created a continuous structure throughout the microstructure

in tr eated C? inserts% )n addition, they declared that the content of the T phase 3?o5 resisting higher

temperatures had

significantly decreased and that additional K phase carbides 3?o/C/?5 had precipitated after cryogenictr eatment%

+imilarly, adi&el and < udr amoor thyand +eah et al% reported that the cryogenic treatment and temper ing

process enhanced the amount of K carbides and homogenously distributed the carbide par ticles%

213 :;D

analy si s

>he 2<6 profiles of the untreated and treated inserts are shown in @igs% a and b, respecti&ely% )t can be

obser&ed from the 2<6 profiles of the treated inserts that K phase carbides 3?o /C/?5 were formed at about 9:

degrees and that the peak intensities of C? significantly increased 3@igs% a and b5% >he new K carbide peaks

are good indications of the increase of carbides after the cryogenic treatment and tempering process, which is

also supported by the results of the image processing 3>able 95%

$ig. . 2<6 profiles of the C?J?o inserts* a5 untreated, b5 treated%

b5a5



23 "ool <ear



231 (lan# <ear

>he &ariations of flank wear of both the untreated and treated inserts at a feed rate of %.4 mm're& and cutting

speeds of ., .9, .; and ./ m'min according to the cutting times are shown in @igs% ;a, ;b, ;c and ;d,

respecti&ely% )n the e7periments, the workpiece materials were turned for 9, 9, / and . min at cutting speeds of

., .9, .; and ./ m'min, respecti&ely% As shown in @ig% ;, flank wear appeared at the first stop time and

increased with increasing cutting time at all cutting speeds% Moreo&er, at all combinations of cutting conditions,

the treated inserts e7hibited better peformance than the untreated ones in terms of flank wear% At a feed of %.4

mm're& and cutting speeds of ., .9, .; and ./ m'min, the flank wear formed on the treated inserts had

impro&ed by ;F, ./F, .0F and 90F in comparison with the untreated inserts% >his can be attributed to

impro&ing wear resistance due to increasing hardness and to the impro&ing microstructure &ia precipitation of

secondary carbides and homogenous distribution of the carbide% Microhardness measurements re&ealed that the

microhardness &alues of the treated inserts had increased by /F when compared to those of the untreated inser ts%

>he hardness &alues of the untreated and treated inserts were measured as .01%: and .:.9%/ ,

respecti&ely% $n the other hand, built-up edge 3IPE5 formed on the cutting edges of both the untreated and

treated inserts% Iuilt-up edge freGuently appears in the cutting of ductile materials% )t is well known that

austenitic stainless steels ha&e a high tendency to adhere to the cutting edge of tools due to their ductile structure%

"erth et al% reported that IPE formed on the cutting tools due to ductility and adhesion tendency of austenitic

stainless steels during their turning operations%

)n addition, it can be obser&ed from @ig% ; that the amount of flank wear had increased with increasing cutting

speed% >he flank wear &alue was %../ mm at a cutting speed of ./ m'min and cutting time of . min, while the

flank wear &alue was %19 mm at a cutting speed of . m'min and cutting time of 9 min, thus clearly

indicating the negati&e effects of the cutting speed on flank wear%igher cutting speeds lead to rapid tool wear due to serious heat generation and rapid plastic deformation %



$ig. %. ariations of flank wear &ersus cutting times at a feed rate of %.4 mm're& and cutting speeds of a5 .

m'min, b5 .9 m'min, c5 .; m'min, d5 ./ m'min%

@ig% 4 shows the &ariations of flank wear on the untreated and treated inserts along with cutting times at a feed

rate of % mm're& and four different cutting speeds% >he treated inserts pro&ed superior to the untreated inserts

in terms of the flank wear formed on them at especially low cutting speeds% At higher cutting speeds, despite the

superior wear performance of the treated inserts, the amounts of flank wear on the untreated inserts and on the

treated inserts were closer to each other% At a cutting speed of . m'min, the flank wear formed on the tr eated

inserts after turning for . min was eGual to that on the untreated inserts for 4 min% >he wear progress at a

cutting speed of .9 m'min was similar to that at the pre&ious cutting speed% At a feed of % mm're& and cutting

speeds of ., .9, .; and ./ m'min, the flank wear formed on the treated inserts impro&ed by 91F, 90F,

.4F and .0F, respecti&ely, in comparison with that on the untreated inser ts%



$ig. &. ariations of flank wear &ersus cutting times at a feed rate of % mm're& and cutting speeds of a5 .


>he &ariations of flank wear along with cutting times at a feed rate of %;4 mm're& and four cutting speeds ar e

gi&en in @ig% /% Ppon e7amination, it can be seen that flank wear had occurred at all cutting speeds% +imilarly, at

this feed &alue, the treated inserts e7hibited better flank wear performance than the untreated ones% At a cutting

speed of . m'min, the flank wear of the treated inserts at a cutting time of / sec was eGual to the wear of the

untreated inserts at a cutting time of sec% $n the other hand, at a cutting speed of ./ m'min, catastrophic

failure nearly occurred on the cutting edge of the untreated inserts, whereas normal flank wear was formed on

the flank face of the treated inserts at the end of the cutting process% >he best flank wear performances were

obtained with the treated inserts at a cutting speed of . m'min% At a feed of %;4 mm're& and cutting speeds of

., .9, .; and ./ m'min, the flank wear formed on the treated inserts had impro&ed by 9F, .4F, 1F and

.0F, respecti&ely, in comparison with the untreated inserts% "ill et al% , adi&el and <udramoorthy , +eah et al%

and ong et al% reported that cryogenic treatment and tempering processes enhanced the abrasi&e wear

resistance of tungsten carbide tools owing to the precipitation of fine K carbide particles and their homogeneous

distribution in the microstructure%



.

$ig. '. ariations of flank wear &ersus cutting times at a feed rate of %;4 mm're& and cutting speeds of a5 .


233 )otch <ear

>he &ariations of notch wear against cutting times at a feed rate of %.4 mm're& and four cutting speeds are

illustrated in @ig% :% At all cutting speeds, it was obser&ed that notch wear had occurred on the main cutting

edges of the carbide inserts% >he treated inserts e7hibited superior performance to the untreated inserts in terms

of notch wear at cutting speeds of . m'min and .; m'min% >he impro&ement percentages in notch wear on

the treated inserts &ersus the untreated ones were .F and ;F, respecti&ely% owe&er, at a cutting speed of .9

m'min, it was determined that the treated inserts showed a .F worse wear performance than the untreated ones

after a turning process of 9 min% +imilarly, at a cutting speed of ./ m'min, the notch wear on the treatedinserts was 0F more than on the untreated ones% At this cutting speed, as notch wear had occurred on both

inserts prior to the final cutting time, a graphic could not be constructed% After a cutting time of . min, the notch

wear &alues formed on the untreated and treated inserts were measured as %.: mm and %.14 mm, r especti&ely%

)n addition, IPE generally formed on the cutting edges of both inserts% )t is known that IPE on the cutting edge

of tools occurs at lower cutting speeds% @ig%0 shows E62 analyses of IPE region% (resence of @e, Ni, ?r, +i,

and Mn on both tungsten carbide inserts is strong e&idence for IPE%



a5 b5

? $ ?r Mn @e Ni C +i Pnits

Pntr eated ;0%;1 9%4 4%14 %/; 99%1 9%9/ .%: - wt%F>r eated 1%4 91%09 4%4 %49 .1%90 9%4; - %:4 wt%F

$ig. (. E62 analyses of IPE and notch regions of the carbide inserts at a feed rate of % mm're& and cuttingspeed of .9 m'min* a5 untreated, b5 treated%

)n general, treated inserts e7hibited better wear performance than untreated ones in terms of notch wear at all

combinations of cutting conditions% owe&er, at only cutting speeds of .9 and ./ m'min, untreated inserts

were superior to treated inserts% >his e7ceptional case can be e7plained by larger IPE% Cear pictures on @ig% 0b

support this claim%



$ig. ). ariations of notch wear formed on the untreated and treated inserts according to cutting times at a feedrate of %.4 mm're& and cutting speeds of a5 . m'min, b5 .9 m'min, c5 .; m'min%

At a feed rate of % mm're&, e&en though notch wear appeared at lower cutting speeds 3. and .9 m'min5, at

higher cutting speeds 3.; and ./ m'min5, it did not form on the main cutting edges of either the untreated or

treated inserts% ift!i clarified this case with the reduction in IPE tendency owing to the increasing cutting

speed, which leads to higher temperatures in the cutting zone% $ne of the most important reasons of notch wear

is o7idation% >he notch wear may occur by chemical reaction of tool material and o7ygen in the air at the

interface between tool and the atmosphere with the effects of high temperatures% igh $ content at the notch

wear region is a good indicator for o7idation 3@ig% 05% As shown in @ig% 1, it was obser&ed that significant

decreases in notch wear on the treated inserts had occurred in comparison with the untreated ones% $n the other

hand, at both cutting speeds, notch wear started to form on the treated inserts at the first stop time, whereas it

appeared on the untreated ones after cutting times of 4 min and . min at cutting speeds of . m'min and .9

m'min, respecti&ely% At a cutting speed of . m'min, the treated inserts showed a significant impro&ement of

/1F in notch wear in comparison with the untreated ones% +imilarly, at a cutting speed of .9 m'min, the

impro&ement was ;:F% >hese findings showed that the cryogenic treatment and tempering processes had

significantly enhanced the wear resistance of the carbide inserts at medium feeds% )n addition, it was obser&ed

that a small incidence of IPE had occurred on the cutting edges of both the treated and untreated inserts%



$ig. *. ariations of notch wear formed on the untreated and treated inserts according to cutting times at a feedrate of % mm're& and cutting speeds of a5 . m'min, b5 .9 m'min%

At a feed rate of %;4 mm're&, no notch wear had appeared on either of the inserts at any cutting speed% >his can

be attributed to the increasing temperatures generated in the cutting zone along with the increasing material

remo&al rate at higher feeds% As the feed rate increases, the section of chip increases and conseGuently friction

increases , this lead to increase cutting forces, especially in thrust direction% )t is obser&ed that the region of high

stresses in the thrust direction turns inward as the feed increases, which may result in the increase in

temperatures generated, so the temperature at interface increases % >he higher temperatures reduced the IPE

tendency%

232 Crater <ear

Measurements of crater depth on the rake faces of the untreated and treated inserts are shown in @ig% .% >he

craters of the treated inserts are shallower than those of the untreated ones at all combinations of cutting speeds

and feeds% At a feed rate of %.4 mm're& and cutting speeds of ., .9, .; and ./ m'min, crater wears on the

treated inserts was reduced by 9F, 4F, 49F and 0F in comparison to those on the untreated ones,

respecti&ely% At a feed rate of % mm're&, the treated inserts e7hibited superior performance by impro&ements of

.F, :F, .F and ;/F at cutting speeds of ., .9, .; and ./ m'min, respecti&ely% +imilarly,

impro&ements in crater wear at a feed of %;4 mm're& were 1F, ./F, .F and F at cutting speeds of ., .9,

.; and ./ m'min, respecti&ely% )n terms of crater wear, the treated carbide inserts e7hibited better performance

at lower speeds than at medium and higher speeds% )t is well known that diffusion occurring because of the

higher temperatures at the tool-chip contact area leads to crater wear% @urthermore, one of the most importantreasons for this diffusion is the chemical affinity between the workpiece and tool materials% )n literature, it was

reported that crater wear significantly decreased owing to chemically inert cutting tools and the decreases in

cutting zone temperatures after cryogenic treatment % Another of the most important causes of crater wear is

abrasion% Abrasion is directly related to the hardness and wear resistance of a cutting tool% As mentioned abo&e,

because of the hardness and wear resistance of the cryogenically treated carbide inserts, they e7hibited a superior

performance compared to the untreated ones%



$ig. 1+. ariations of crater wear on the untreated and treated inserts at feeds of a5 %.4 mm're&, b5 % mm're&,c5 %;4 mm'r e&%

234 Evaluation of SE+ *ictures

)n order to elucidate the wear mechanisms, +EM pictures of the untreated and treated inserts worn at feeds of

%.4, % and %;4 mm're& are gi&en in @igs% .., .9 and ., respecti&ely% )t was obser&ed that flank wear had

formed on both the untreated and treated inserts as a result of the abrasi&e wear mechanism 3@ig% ..5% )n

addition, notch wear had appeared on them at all cutting speeds due to o7idation and the adhesi&e wear

mechanisms% +imilarly, IPE was obser&ed on the cutting edges of both the treated and untreated inserts% $n the

other hand, craters had occurred on the rake faces of all inserts at all speeds as a conseGuence of abrasi&e and

diffusion wear mechanisms, and some material transfers from the workpiece material were obser&ed on the

surfaces of the craters% @ig% .; also shows the material transfers along the crater surfaces% >he presence of the

elements @e and +i was a strong indication of the material transfer% +ince a strong chemical affinity e7ists

between stainless steel and the carbon in tungsten carbide, diffusion is ine&itable at the tool-chip interface in the

turning of stainless steels with uncoated tungsten carbide inserts% owe&er, at a feed rate of %.4 mm're&, it was

obser&ed that the craters formed on the rake faces of all inserts were not deep or large enough to ad&ersely affect

the cutting performance 3@ig% ..5% >his type of wear depends considerably on the temperature in the cutting

zone% ence, cutting conditions such as cutting speed and feed are &ery important%



U. m'min U.9 m'min U.; m'min U./ m'min

a5

b5

$ig. 11. +EM pictures of wear on the carbide inserts at a feed rate of %.4 mm're&* a5 untreated, b5 tr eated%

)n the +EM pictures of the inserts used to turn the stainless steel bars at a feed rate of % mm're& 3@ig% .95, it can be seen that the amount of wear at this feed is more dramatic than at a feed of %.4 mm're&% )n particular, notch

wear had reached a ma7imum at this feed while crater wear was greater and deeper than at a feed of %.4

mm're&% )n addition, it was determined that the notch wear had occurred on the end cutting edges of both the

untreated and treated inserts at a cutting speed of . m'min% Although IPE formed on both inserts, the amount

of IPE on the untreated inserts was Guite large when compared to that on the untreated ones% $n the other hand,

the notch wear on the main cutting edges of the untreated inserts was about three times greater than that on the

untreated ones% @urthermore, the IPE and chippings on the cutting edge of the untreated inserts had caused

significant deterioration of the uniformity of their cutting edges% At a cutting speed of .9 m'min, while notch

wear had appeared on the end cutting edges and plastic deformation on the nose of the untreated inserts, these

types of wear were not obser&ed on the treated inserts% (lastic deformation occurs when high pressures 3i%e%

compression5 are e7erted on the cutting edge in combination with ele&ated temperatures% )t leads to the

generation of higher temperatures in the cutting zone, geometric deformation of the insert, and &ariation of the

chip flow on the rake face% >o a&oid this type of wear, turning inserts should ha&e higher hot hardness % <eddy et

al% reported that cryogenically treated tungsten carbide inserts had higher hot hardness than untreated ones% $n

the other hand, the amount of flank wear on the treated inserts was greater than on the untreated ones% )n

addition, notch wear was obser&ed on the main cutting edges of both inserts% At cutting speeds of .; m'min and

./ m'min, no notch wear occurred on either the main cutting edges or end cutting edges of the untreated or

treated inserts because the IPE tendency had decreased as a result of the higher temperatures generated at the

higher cutting speeds %




a5

b5

$ig. 12. +EM pictures of wear on the carbide inserts at a feed rate of % mm're&* a5 untreated, b5 tr eated.

At a feed of %;4 mm're& 3@ig% .5, no notch wear on the main cutting edges of either the untreated or treated

inserts was encountered% owe&er, at a cutting speed of . m'min, because of the higher temper atur es

generated at the higher feed rates, the amount of IPE was less than that of other feeds% $n both untreated and

treated inserts, notch wear appeared only on the end cutting edges% )n addition, at a cutting speed of ./ m'min,

while the treated inserts e7hibited gradual wear, the untreated inserts reached catastrophic failure 3fracture5

owing to the e7cessi&e mechanical loads occurring at higher feeds% >reated inserts were superior to untreated

inserts in terms of chipping and fracture% Cear types such as chipping and fracture are related to fr actur e

toughness of a cutting tool material% <eddy et al% and "ill et al% claimed that cryogenic treatment impro&ed

toughness of tungsten carbide tool materials% Also residual stresses in the material resulted due to sintering of

tungsten carbide inserts are relie&ed during cryogenic treatment% >hese micro-stresses are the leading cause of

early carbide fracture % )n addition, crater wear formed on the rake face of all inserts, and material transfers from

the workpiece material formed on their crater surfaces% >he craters of the untreated inserts were deeper than

those of the untreated ones%


a5

b5

$ig. 1. +EM pictures of wear on the carbide inserts at a feed rate of %;4 mm're&* a5 untreated, b5 treated%



a5 b5

$ig. 1%. E62 analyses for crater surfaces of the carbide inserts at a feed rate of % mm're& and cutting speed of .9 m'min* a5 untreated, b5 treated%

%. ,onclusion

)n this study, the effects of deep cryogenic treatment on tool wear were in&estigated in the turning of A)+) ./

austenitic stainless steel with uncoated cemented carbide inserts% )n conseGuence of the analyses and turning

e7periments performed, the findings obtained in this study are as follows*

V As a result of image processing analysis, it was found that the amount of fine K carbides in the deep

cryogenically treated inserts had increased by 4%;F in comparison to that of the untreated ones% @ine K

carbides impro&e the hardness and wear resistance% Microhardness measurements showed that the hardness

&alues of the treated inserts had increased by /F when compared to those of the untreated inserts%

V ?ryogenic treatment led to an increase of 1F in the grain size of the treated inserts with respect to that of the

untreated ones% >his larger grain size caused to an increase in C? grain contiguity and to increases in the

thermal conducti&ity of the treated inserts%

V At all cutting conditions, the treated inserts showed a better performance than the untreated ones of up to

;F and 4F in terms of flank wear and crater wear, respecti&ely% owe&er, while the treated inserts

e7ibited a notably superior performance of up to /1F compared to the untreated ones in terms of notch wear

at a medium feed rate 3% mm're&5, at a lower feed rate 3%.4 mm're&5, the impro&ement of the treated

inserts in tool performance did not e7ceed /1F%

As a result of wear e7periments and &arious analyses, cryogenic treatment was shown to significantly impro&e

the hardness and wear resistance of the tungsten carbide inserts% >his impro&ement can be e7plained by theincreases in grain size, additional formation of fine K carbide percentage, and high thermal conducti&ity%

Ac-nowledgement

>he authors wish to place their sincere thanks to "azi Pni&ersity +cientific <esearch (ro8ect 6i&ision for

financial support for the (ro8ect No% 0'9.-9%



"eferences

W.X "ill ++, +ingh =, +ingh , +ingh <% Metallurgical and mechanical characteristics of cryogenically treated

tungsten carbide 3C?J?o5% )nt = Ad& Manuf >ech 9.9Y4:*..1J.%

W9X @irouzdor , Ne8ati E, Lhomamizadeh @% Effect of deep cryogenic treatment on wear resistance and tool

life of M9 ++ drill% = Mater (rocess >echnol 9:Y9/*;/0-09%

WX i!ek A, Pygur Z, L[&ak >, Altan Özbek N% Machinability of A)+) ./ austenitic stainless steel with

cryogenically treated M4 high-speed steel twist drills% = Manuf +ci Eng 3A+ME5 9.9Y.;*.-/%

W;X Akhbarizadeh A, +hafyei A, "olozar MA% Effects of cryogenic treatment on wear beha&ior of 6/ tool steel%

Mater 6es 91Y*941J/;%

W4X uang =, Rhu >, Hiao 2R, Ieyerlein )=, Iourke MA, Mitchell >E% Microstructure of cryogenic tr eated

M9 tool steel% Mater +ci Eng A 9Y1*9;.-;%

W/X Hiu , Cang =, ang , +hen I% Effects of cryogenic treatment on microstructure and abrasion r esistance

of ?rMnI high-chromium cast iron sub8ected to sub-critical treatment% Mater +ci Eng A 9:Y;0:*9;J:%

W0X Cang =, 2iong =, @an , ang +, Hiu , +hen +H% Effects of high temperature and cryogenic treatment

on the microstructure and abrasion resistance of a high chromium cast iron% = Mater (rocess >echnol

91Y91*9/J;%

W:X Lao M% >he effect of cryogenic treatment on sintered tungsten carbide% MasterOs thesis* Arizona +tate

Pni&ersityY.1:;%

W1X Iryson CE% ?ryogenics% anser "ardner (ublications, ?incinnati Y .111, p% :.J.0%

W.X <eddy >+, +ornakumar >, <eddy M, enkatram <% Machinability of ?;4 steel with deep cryogenic

treated tungsten carbide cutting tool inserts% )nt = <efract Met ard Mater 91Y90*.:.J4%

W..X adi&el L, <udramoorthy <% (erformance analysis of cryogenically treated coated carbide inserts% )nt =

Ad& Manuf >ech 91Y;9*999J9%

W.9X ong AH, +eah LC, <ahman M% (erformance e&aluation of cryogenically treated tungsten carbide

tools in turning% )nt = Mach >ool Manufact 9/Y;/*94.-/%

W.X <am8i I<, Murthy NN, Lrishna M% Analysis of forces, roughness, wear and temperature in turning cast

iron using cryotreated carbide inserts% )nt = Eng +ci >echnol 9.Y9*949.-1%

W.;X "rzesik C% Ad&anced Machining (rocesses of Metallic Materials* >heory, Modelling and Applications%

Else&ier* HondonY 9:%

W.4X Altan Özbek N, i!ek A, "#lesin M, Özbek $% )n&estigation of the effects of cryogenic treatment applied

at different holding times to cemented carbide inserts on tool wear% )nt = Mach >ool Manufact 9.;Y:/*;J

;%

W./X +eah LC, <ahman M, ong L% (erformance e&aluation of cryogenically treated tungsten carbide

cutting tool inserts% (roc )nstn Mech Engrs 9Y9.0*91J;%

W.0X "erth =, "usta&sson @, ?ollin M, Andersson ", Nordh H", einrichs =, Ciklund P% Adhesion phenomena

in the secondary shear zone in turning ofaustenitic stainless steel and carbon steel% = Mater (rocess >echnol

9.;Y9.;*.;/0J:.%

W.:X +mith ">% ?utting >ool >echnology* )ndustrial andbook% +pringer* HondonY 9:%



W.1X iftci Z% Machining of austenitic stainless steels using ?6 multi-layer coated cemented carbide tools%

>ribol )nt 9/Y1*4/4J1%

W9X +haw M?% Metal cutting principles% $7ford Pni&ersity* HondonY .1:;%

W9.X Aouici , allese M, @nides I, Mabrouki >% Machinability in&estigation in hard turning of A)+) .. hot

work steel with ?IN tool% Mechanika 9.Y/3:/5* 0.-0%

W99X aseen +=% >heoretical study of temperature distribution and heat flu7 &ariation in turning process% Al-\adisiya = Eng +ci 9.9Y435* 911-.%

W9X i!ek A, L[&ak >, Pygur ), Ekici E, >urgut % (erformance of cryogenically treated M4 ++ drills in

drilling of austenitic stainless steels% )nt = Ad& Manuf >echnol 9.9Y/*/4J0%

W9;X <eddy >+, +ornakumar >, <eddy M, enkatram <% )mpro&ement of tool life of cryogenically treated (-

tools% )n* (roceedings of )nternational ?onference on Ad&anced Materials and ?omposites 3)?AM?-

905 at National )nstitute for )nterdisciplinary* >ri&andrumY 90%

W94X "ill ++, +ingh =, +ingh , +ingh <% )n&estigtion on wear beha&iour of cryogenically treated >iAlN coated

tungsten carbide inserts in turning% )nt = Mach >ool Manufact 9..Y4.*94-%

I/0I/T

V ?ryogenic treatment led to an increase of 1F in the grain size ofcarbide inser ts%

V Amount of fine K carbides increased by 4%;F after cryogenic treatment%

V >reated inserts showed a better performance in terms of flank wear and crater wear%

V Notch wear occurred only at lower and medium cutting speeds and feed rates%

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