Steel abrasive wear forecasting by wearing surfaces microgeometric parameters/Plienu abrazyvinio dilimo prognozavimas pagal dylancio pavirsiaus mikrogeometrinius parametrus.
Jankauskas, V. ; Skirkus, R.
1. Introduction
Abrasive wear is the most intensive, loss-making mechanical wear
type. Machine elements, what works in the soil wear rates can reach 12.7
mm/h [1].
For wear estimation can be used many methods, but in practice are
used just few of them. Normally its selectable method, with required
accuracy and what guarantees lower costs and its time efficient. These
methods are micrometer, mass, artificial bases, profilography and other
methods, which are selectable by required accuracy, price and speed of
measurement [2].
The type and intensity of abrasive wear depends on abrasive mass
(particle size, form, composition, hardness, dampness) and the wearing
surface properties (composition, hardness), and also the abrasive
particle and surface hardness ratio [3].
Abrasive mass abrasivity is ranked by particle hardness, size and
sharpness. The harder, higher and sharper particles, then the wear is
intensive [4].
Soft abrasive medium wear caused by surface multiply plastic
deformation (fatigue) principle--wear is slow and acceptable [2]. Fixed
abrasive particle in solid body surface creates microcuts with depth of
0.001 0.02 mm [5]. The wearing surface is softer then easier abrasive
particle can go deepen with increasing the wear. Because of this rule,
roughness of wearing soft surface is higher.
In literature [3, 5-8] the hardness is referred as the main
property which has influence to abrasive wear resistance, i. e. the
harder the steel surface, the higher to abrasive wear resistance it has.
But actually the abrasive wear resistance determines composition and
microstructure of steel [2].
Wear intensity depends directly from the met al microhardness [5].
As a rule, increasing the hardness increases the abrasive wear
resistance. The abrasive particles in to the harder layer can less
penetrate and less plastically deform. The exception to this rule can do
microstructure features. It was found that the wear in the abrasive
mass, steel 65G tempered in oil (30-35 HRC) wearing less than the steel
tempered in water (58-60 HRC) [9].
Wear influence the steels tensile strength. High-tensile steel is
less resistant to abrasive particles penetration into the steel, but the
deformed surface returns to its original shape and not damaging the
surface if it's not exceeded its elastic limit. The steels, who
don't have the elastic properties, are more resistance to abrasive
particle penetration, but its brittle [10].
In ideal case, intender, with significantly higher hardness than
wearing surface hardness, scratching softer surface and leaves mirror
trace (grove), Fig. 1.
[FIGURE 1 OMITTED]
Intender traces in plastic and hard (brittle) surfaces leaves
different tracks (Fig. 2) [7]. In plastically surface beside trace, the
dump is created while on brittle surface grove border crumbles.
[FIGURE 2 OMITTED]
Ductile surface wear is calculated by surface, affected by the
indenter, the difference between the areas before and after the impact
of inventory [7]:
[Florin] or [Guilder].sub.ab] - [A.sub.1] + [A.sub.2]/[A.sub.v];
[DELTA][V.sub.d,ductile] = [Florin] or [Guilder].sub.ab] [A.sub.v/A
= [Florin] or [Guilder].sub.ab][PHI]P/[H.sub.def],
where: ([A.sub.1] + A.sub.2]) is the cross-sectional area of the
material displaced at the edges of the groove when the material is
ductile; [A.sub.V] is the cross-sectional area of the wear groove;
[Florin] or [Guilder].sub.ab] is the ratio of the amount of material
removed by the passage of a grit to the volume of the wear groove; [PHI]
is a factor depending on the shape of the abrasive particles; P is the
externally applied surface pressure. The pressure is assumed to have a
uniform value, e.g. uniformly loaded sand paper; [H.sub.def] is the
hardness of the material when highly deformed.
Brittle surface, affected by the indenter, wear is calculated by
the difference between the areas before and after effects of the
indenter, but because of the extra brittle fracture zones, calculation
is more complex [7]:
[DELTA][V.sub.d,brittle] = [[phi].sub.1]/[H.sub.def] +
[[[phi].sub.1][A.sub.f][D.sub.ab][P.sup.1.5][H.sup.0.5][[mu].sup.2][OMEGA]/ [K.sub.2.sub.IC]] (3)
[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (3)
where: [mu] is the coefficient of friction at the leading face of
the abrasive particles; [D.sub.ab] is the effective size of the abrasive
particles; [THETA].sub.1], [THETA].sub.3] is a factor depending on the
shape of cracking during abrasive wear. For pyramidal shape particles;
[OMEGA] is a parameter defined as [OMEGA] =
1-exp[(-(p/[p.sub.crit]).sup.05]); [K.sub.IC] is the fracture toughness
under tension.
Analytical evaluation of wear, when evaluating various compositions
of the steels has severe limitations: an extremely different friction
coefficient, underestimating the plastic deformation degree, indenter
sharpness and so on [7]. It does not guarantee a minimum evaluation of
accuracy.
Structural, heat-finished, mild steel (including spring-steel)
hardness can reach up to 4-6 GPa.
Steels with plenty wide range of hardness has elastic properties,
so it is likely that [theta].sub.Brittle] > [theta].sub.Ductile],
accordingly, surface, roughness top angles with differing elastic
properties will be different.
Steel, impacted with indenter, elastic and brittle profiles
scratches angle will vary by materials elastic deformation size.
Resilience inevitable in contact: indenter breaking the surface,
therefore the material tension is greater, the greater will be the
groove angle change from the indenter profile. Wherewith bigger tension
difference, the greater and more accurate are calculation of difference
between wear traces and wear values.
Abrasive particles abrasivity are valued by them and by wearing
surface form analytically determined parameter spike parameter-quadratic
fit (SPQ) [12].
Both methods are similar, they are based on the theoretical
Rabinowicz method i.e. the interaction model between a precise cone
shape particle and the surface [11, 13].
The profile of a wear trace is measured perpendicularly to the
abrasive motion direction. The result is estimated by standard roughness
parameter [R.sub.a] and SPQ parameter [13, 14]. The SPQ parameter
evaluates the surface profile with respect to the irregularities shape
[13, 14]:
SPQ = 1/n [summation over n] cos [theta].sub.i]/2, (4)
where n is the number of measured irregularities at a chosen
distance; [[theta].sub.i] is measured angle of the i-th irregularity
apex (Fig. 4).
Surface profile parameter SPQ is analytically determined parameter
(4), for which calculation is necessary to determine the angle [theta].
Therefore in practice reasonable is direct relation between roughness
peak angle value and wear rate value.
[FIGURE 3 OMITTED]
SPQ parameter applied to the evaluation of different hardness
steels wear (medium-carbon 45 and tool steels XB[GAMMA]) affected by
abrasive wear [4]. Wear was modeled with rubber wheel according ASTM
G65-94 [15].
During the test abrasive particles are pressed to the testing
surface with the force, depending from load, particle size and rubber
hardness. Contacting pressure force also depends from the particle
shape. Particles on wearing surface sliding and rolling. Therefore more
accurate result for the relation between wear and surface
microgeometrical parameters will be received while performing wear test
by fixed abrasive.
We accept that, abrasive paper grain average statistical peak angle
perpendicular to the direction of movement the plane is constant.
Therefore, the ideal inventory damage (easily cut and no deformable)
surface profile will be the same. The real surface roughness profile
differences will be formed by met al tension properties. Due to these
met al surface roughness (scratches) properties the peak angle in
perpendicular to wear direction plane will not have any relation between
indenter (abrasive particles) profile angles.
The aim of this work--determine the steel wearing surface roughness
peak angles relation with wear, and also creating preconditions for
steel resistance to abrasive wear research methodology with wear by
fixed abrasive.
2. Research methodology
For wear surface microgeometric parameters and wear relation
evaluation was used low carbon boron micro alloyed steel Hardox 400
(further H400, SSAB Technology AB), medium carbon steel 45 (GOST
1050--88), carboniferous (spring) steel 65G (GOST 14959--79).
The steel composition and hardness obtained by heat treatment are
given in Table 1. For heat treatment was used stove SNOL 8.2/1100 L.
Sample size 20x15x7 mm.
For wear by fixed abrasive research was selected friction pair type
pin--on--drum" (ASTM G 132-96 (2007)). By abrasive paper coated
drum diameter 90 mm, applied load 28 N. The feed of 0.57 mm/rev with a
drum revolving 63 [min.sup.-1] (v = 0.3 m/s). Test repeatability--3.
Chemical composition of the samples is determined by a spectrometer
BELEC-compact-lab-N, hardness is measured with a hardness tester TK-2M.
The wear is evaluated by method of mass los with the scales KERN EG
420-3NM (accuracy 0.001 g).
For research was used [Al.sub.2][O.sub.3] abrasive paper (Olimpus
Abrasives Co), type KX167 with grain size P100 (average abrasive
particles size 160 [micro]m). Weared surface roughness was investigated
with profilograph MahrSurf XR20. Surface profile angle perpendicular to
the direction of motion of the plane was measured by processing
profilogramm image with program Solid Edge ST5.
3. Results
The wear (average values) determined in this research given in
Table 2.
By measuring sample surface profile across wear trace roughness
[R.sub.a] Table 2, profilogramm (view) analyzed with program Solid Edge
ST5--measured microroughness peak angles [theta] Table 2. It was found,
that identical chemical composition, but different hardness (different
structure) material wear trace is different. Abrasive particle strips
for softer surface samples are rough and for harder surfaces wear traces
smoother.
Hardness H, roughness [R.sub.a] and profile peak angles [theta]
relation with wear graphically given in Figs. 4-6.
Low carbon boron micro alloyed steel Hardox 400 wear in fixed
abrasive equally reliable linear characteristic describes his toughness
and roughness. The harder the steel, the less it wears (I = -0.001H +
0.84, [R.sup.2] = 0.84) (Fig. 4, a). The wearing surface is rougher, the
higher wear (I = 0.28[R.sub.a] + 0.07, [R.sup.2] = 0.84), (Fig. 4, b).
Meanwhile wearing surface profile peak angles, weakly characterizes the
amount of wear (/ =--0.03[THETA] + 1.37, [R.sup.2] = 0.49), (Fig. 4, c).
It is likely that such characteristics reason is formed very narrow wear
profile peaks angles range--only 4.7 degrees (from 22.5 to 27.2).
[FIGURE 4 OMITTED]
Medium carbon content steel 45 for wear resistance estimation best
parameter is steel hardness (I = -0.01H + 0.88, [R.sup.2] = 0.83), (Fig.
5, a). Close to this steel wear evaluation parameter is wearing surface
profile angle--the profile microroughness peak angle is bigger (tops
obtuse) (I =--0.026[THETA] + 1.45, [R.sup.2] = 0.76), the material has
higher resistance to wear (Fig 5, c). Meanwhile, the wearing surface
roughness has a weak relationship with abrasive wear ([R.sup.2] = 0.55),
(Fig. 5, b).
[FIGURE 5 OMITTED]
Carbon (spring) steel 65G, what variety of microstructures very
strongly influences the wear resistance and hardness is not a reliable
parameter to describe the resistance to abrasive wear (I = 0.001H +
0.86, [R.sup.2] = 0.53), (Fig. 6, a). Surface roughness well describes
the wear rate (I = 0.38Ra--0.39, [R.sup.2] = 0.85), (Fig. 6, b). The
more surface is stronger carved, the less it is resistant to wear. In
this case roughness is more reliable parameter than hardness. Steel 65G
resistance to wear best reflect the wearing surface profile angle. This
steel roughness profile peak angle range is wide--16.4 degree (18.2 to
34.4). The more profile tops angle smaller, the surface wears more
intensively (I =--0.024[THETA] + 1.24, [R.sup.2] = 0.95) (Fig. 6, c).
The results suggest that the steel abrasive wear can be predicted
not only by the hardness, but also by the roughness of the wear track
and the wear track profile tops size of angles. The more surface is
resistant to abrasive wear the trace smoother and vice versa. Evaluation
of carbon steel wear trace by profile tops angle established reliable
relationship ([R.sup.2] = 0.95), the relationship between the wear rate
and surface profile angles. Therefore, carbon steel with a wide hardness
range resistance to wear by fixed abrasive is appropriate by the wear
trace profile tops angles.
[FIGURE 6 OMITTED]
4. Conclusions
Low carbon steel wear by fixed abrasive can be predicted from their
hardness and wearing surface roughness, medium carbon steel--hardness
and wearing surface profile tops angles, carbon steel--wearing surface
roughness and wearing surface profile tops angles.
The higher the evaluated material hardness difference, the wider
range of profile tops angles, the better can be forecast wear. Wear
evaluation by surface roughness or wearing surface profile tops angle
has the comparative evaluation (practical) sense, for example,
evaluation under the same conditions working parts for resistance to
abrasive wear, where other estimation methods is complicated or
impossible.
References
[1.] Pigors O. 1993. Werkstoffe in der Tribotechnik Reibung,
Schmierung und Verschleissbestandigkeit von Werkstoffen und Bauteilen,
Leipzig: Deutscher Verlag fur Grundstoffindustrie, 546p.
[2.] Blau, P. 2010. ASM Handbook, Vol. 18. Friction, Lubrication,
and Wear Technology. ASM International, 1879p.
[3.] Khrushchev, M.M.; Babichev, M.A. 1970. Abrasive Wear, Moscow:
Science, 252p. (in Russian).
[4.] Jankauskas, V.; Kreivaitis, R. 2007. Study of wear prediction
by applying surface microgeometric parameters, Mechanika 5(67): 65-70.
[5.] Garkunov, D.N. 2001. Triboengineering: Wear and No - Wear,
Moscow: MCXA, 616p. (in Russian).
[6.] Heinrich, R. 1995. Untersuchungen zur Abrasivitat von Boden
als Verschleissbestimmender Kennwert, Technische Universitat
Bergakademie Freiberg, 99p.
[7.] Stachowiak, G., Andrew, B. 2005. Engineering Tribology, Third
Edit, Elsevier, 832p.
[8.] Tkachiov, V.N. 1995. The efficiency of machine parts under
conditions of abrasive wear, Moscow: Mashinostroenie, 336p. (in
Russian).
[9.] Jankauskas, V.; Zunda, A.; Slapelis, A. 2004. Steels Lubor
044, 65G and L53 wear in abrasive environment research, Agricultural
Engineering 36(3): 63-74 (in Lithuanian).
[10.] Callister, William D. 2012. Fundamentals of Materials Science
and Engineering Fifth edition, 4th edition, New York: John Wiley &
Sons, 936p.
[11.] De Pellegrin, D.V., Stachowiak, G.W. 2001. A new technique
for measuring particle angularity using cone fit analysis, Wear 247(1):
109-119. http://dx.doi.org/10.1016/S0043-1648(00)00512-3
[12.] Stachowiak, G.W. 2000. Particle angularity and its
relationship to abrasive and erosive wear, Wear 241(2): 214-219.
http://dx.doi.org/10.1016/S0043-1648(00)00378-1
[13.] Stachowiak, G.W. 2006.Wear: Materials, Mechanisms and
Practice, Wiley. 458p.
[14.] Hamblin, M.G., Stachowiak, G.W. 1997. Characterisation of
surface abrasivity and its relation to two-body abrasive wear, Wear
206(1-2): 69-75. http://dx.doi.org/10.1016/S0043-1648(96)07323-1
[15.] ASTM. ASTM G65--04(2010) Standard Test Method for Measuring
Abrasion Using the Dry Sand/Rubber Wheel Apparatus, 12p.
Received March 19, 2012
Accepted June 17, 2013
V. Jankauskas *, R. Skirkus **
* Aleksandras Stulginskis Universitety, Studentu 11, 53361,
Akademija, Kauno r., E-mail: vytenis.jankauskas@asu.lt
** Aleksandras Stulginskis Universitety, Studentu 11, 53361,
Akademija, Kauno r., E-mail: remigijus.skirkus@yahoo.com
cross ref http://dx.doi.org/10.5755/j01.mech.19.4.5049
TABLE 1
In research used steels chemical composition and hardness
Sample Chemical compositions of steels, wt. %
C Si Mn Cr Ni Mo B Other
Cu
45 0.46 0.27 0.65 0.25 0.25 -- -- 0.25
65G 0.7 0.35 1.2 0.25 -- -- -- --
H 400 0.15 0.70 1.60 0.30 0.25 0.25 0.004 --
Sample
Fe
45 Remaining content
65G
H 400
Steel heat treatment and get hardness, HV
Variant Steel H400
I Anneal 780[degrees]C 122
II Tempered in water 870[degrees]C and 225
2 h released 650[degrees]C
III Tampered in oil 870[degrees]C 235
IV Tampered in water 870[degrees]C and 294
2 h Released 400[degrees]C
V Tampered in water 870[degrees]C and 392
2 h Released 150[degrees]C
VI Rolled steel (purchasing condition) 413
Steel heat treatment and get hardness, HV
Variant 45 65G
I 138 235
II 227 302
III 335 327
IV 310 382
V 447 675
VI 179
TABLE 2
In research used steel H400, 45 and 65G hardness, wear,
profile peak angles, roughness
Variant Hardness Wear I, g Angle[theta], Ra, [micro]m
H, HV degree
Hardox 400
I 122 0.795 22.5 2.58
II 225 0.663 22.7 2.19
III 235 0.624 26.6 1.89
IV 294 0.652 23.7 2.02
V 392 0.589 27.2 1.83
VI 413 0.552 25 1.96
Steel 45
I 138 0.842 26.1 2.31
II 227 0.685 30.9 2.01
III 335 0.602 35.4 1.71
IV 310 0.702 27.6 2.33
V 447 0.539 32.7 1.98
VI 179 0.774 26.5 2.23
Steel 65 G
I 235 0.781 18.2 2.90
II 302 0.666 26.8 2.90
III 327 0.428 34.1 2.38
IV 382 0.659 24.2 2.74
V 675 0.395 34.4 1.96