determination of the erosion resistance of a carbon steel in a multi

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DETERMINATION OF THE EROSION RESISTANCE OF A CARBON STEEL IN

A MULTI-FLOW

SUMMARY

Despite the importance of the phenomenon and Its impact erosive, the information

provided by the scientific community is not enough, especially In Colombia, Even Though

the research shows Relevant details, Henco, this Phenomenon Has Been Studied in

carbon steel Which Is Used in the oil industry. The tests Were Conducted in an along

erosion cell electrode with a rotating cylinder with rotation Speeds Between 1.0 and 4.0 m /

s, particle size between 50-150 microns in deionized water. The was calculated erosion

rate, type of damage "and Their synergistic relationship of the system and Influence on

steel studios.

Keywords: Erosion, Rotating cylinder electrode (RCE), Multiphase system.

INTRODUCTION

The constant impact of particles against the surface creates a permanent localized

damage leads to material removal by different mechanisms, mainly mechanical and micro

deformations fracture, or a combination of both (Vincent et al 2004).

In the weathering process, two mechanisms which form the basis of the phenomenon,

thus describing sequential mode damage. In ductile materials, the incidence of the particle

generates a sharp erosive deformation located, as well as strain hardening and crusting. In

such cases, geometry of deformation due to the impact of particles depends mainly on the

impact velocity.

On the other hand, in brittle materials is deteriorating caused by cracking and spalling

fracture small parts of the material (Peña, 2001).There a large number of factors that

assume a role factor in the erosion process materials engineering, mainly of steel. Data

Selected experimental results reveal valuable for further research.

Rao and Buckley (1985) found that both surface energy and tension, volume atomic,

melting point, specific energy merger and hardness exhibit good correlation with erosion.

However, these properties are not satisfactory in predicting the erosion rate relative

certain steels. Probably no such properties are sensitive enough to respond small

differences that ultimately reflect subtle differences in morphology or susceptibility

to fracture of hard phases in the deformed microstructure of steels.

Levy (1986) investigated carbon steels and alloys aluminum, finding that the materials

indicated hardness values and higher resistance presented likewise the highest erosion

rates. It then think that the more ductile alloys stop erosion through the power distribution

kinetics of particles through the deformation plastic in the region of the impact zone,



reducing and the stress concentration at the point of impact and in turn lessening the

damage mechanism. Also the ductility, as a measure of capacity elongation, is more

closely associated with resistance to erosion than other mechanical properties

materials. The rate of erosion can be expressed in grams per square millimeter per minute

(G/mm2/min) and in milligrams per centimeter square per minute (mg/cm2/min). You can

also be defined as the mass loss of particles hit the surface of the material. This definitionis useful if the damage caused by particles that affect on this is of primary interest.

The mass transfer is undoubtedly a parameter significant in understanding the erosion

phenomenon is essential to establish the factor that will help develop better terms of the

variables involved in the process, and has discovered that under erosion conditions, the

transfer coefficient mass is increased by:

• The removal in the turbulence from passing particles through the boundary layer.

• The increase in the turbulence from passing particles through the boundary layer.

• The increase in roughness result of erosion. The effect of erosion is progressive, the damage increases as more and more solid articles

entering the system, moreover, the shape and angularity of they play a definitive role in the

mechanism deterioration.

PARAMETERS AFFECTING EROSION.

According to Finnie (1960), knowledge of each and every one of the factors that affect the

process erosion is essential, especially when attempts to develop an appropriate model

that describes the phenomenon. Obviously, variations in physical, chemical and

mechanical, as well as the dynamic behavior of both the material causing and the suffering

erosion, should be considered. One of the main factors that may affect erosion rates are:

• Concentration of particles. • Flow velocity (speed of impact of particles).

• Angle of impact. • Particle size.

• Morphology of the particles.• Density, hardness and brittleness of the particles. • Nature of the fluid.

• Type of flow. • Nature of material.

The influence of the first five factors on erosion rate is very strong and any changein them can affect the speed intensely deterioration of the material.



PARTICLE VELOCITY.

Finnie (1960) reported that the erosion rate of a SAE AISI 1020 is proportional tothe speed impact, that is:

ε = bV ^ n

Where V is the velocity of the particles and n corresponds to the value of 2. Yearslater he reported Work on other materials resulting a range of values of n between2.05 and 2.44. Goodwin et al. (1970) studied the influence of speed impact on thesurface of other materials. Such Researchers analyzed the influence of speed for ranges between 200 and 1800 ft / s using different quartz sizes from 25 to 210microns on a steel 11% chromium, concluding then that erosion rate is dependenton the speed impact according to the relationship:

ε = cV ^ α

Where the exponent α varies from 2 to 2.3. Subsequent investigations, in whichsizes using 125 to 150 microns quartz at different angles of impact found that theexponent for the erosion rate approached 2.3 for all materials tested. However,values as high as 6.5 have also been reported, also, tests carried out steels with11% chromium using sands with sizes 10 to 150 microns for angles of 20 and 90degrees was confirmed dependence on the speed and indicated that it is notwas affected by the angle of impact. Bitter (1963) reported that there is a criticalvelocity below erosion is not the case, but the calculated values are very low (lessthan 10 ft / s) so they can be usually neglected.

PARTICLE SIZE

The implementation of the energy dissipation criterion as a factor controlling theloss of material erosion has led to investigate the effect of size particle.

Comparing this effect with respect to erosion rate can be made binding energydissipation with the loss of material through determining the values of specificenergy, the kinetic energy of impact required to remove unit volume of testmaterial.

For ductile materials, the relative erosion is essentially independent of particle sizeabove certain critical value. Stack et al. (2003), found that the erosion rate isdependent erodente size in the range of 50 to 100 microns, but for values of particle size greater than 100 microns, the dependence of the erosion rate isreduced considerably.

PARTICLE CONCENTRATION

It is known that the effect of concentration particles in the erosion rate of materials



is progressive, the rate increases as more and more particles entering the system,the increased presence of abrasive material around causes damage considerablymore severe, however, some Research shows a critical value above which theinfluence of this variable is reduced considerably. Clark (1991 and 2002) foundthat the mass loss of material does not increase linearly with solids loading, such

nonlinearity side said a particle-particle interference. Additionally, he suggestedthat this interference is significantly above 2% by volume.

CONDITIONS EXPERIMENTAL

The tests were conducted in an electrode rotating cylinder, for which we used acell erosion amended as shown in Figure

1. The modified cell of erosion, consisting of a shell of polymethylmethacrylate witha capacity of 200ml solution, the core is constructed of Nylon the which is joined tothe rotary cylinder, which is a dynamic test team with a rotation speed variable, thecell has four main speakers, designed to reduce the vortices generated by rotationof the system and also to ensure erosive particles collision the study sample. Inthis work we studied three rotation speeds: 1000, 2000 and 3000 rpm.

Work samples were manufactured in AISI SAE 1020, with the followingdimensions: 3.8 cm in diameter external, internal diameter 3.2 cm, 1 cm high and12 cm2 of surface area exposed to erosion phenomenon, the surfaces sampleswere kept free from dust, moisture and other pollutants were subsequentlyroughened with silicon carbide paper, number 120, 240, 320, 400 and 600. After polishing process, the specimens were washed with distilled water, degreasedwith acetone and placed in a desiccator.

Erosive particles used were silica high purity that can be seen in Figure 2, whichand 150μm size was 50 microns and in concentrations of 10 and 30% byweight. The results obtained by analysis chemical sand used are shown in table

1. The impact velocities were 1 and 4 m / s and impact angles were randomly aspresented in a pipe with turbulent flow.

Table 1 Chemical analysis of the sand sample.

% Compound found in the sample Al2o3 Fe2O3 CaO MgO K2O Na2O SiO2

0,094 0,028 0,033 0,060 0,107 0,027 99.65

For the determination of the erosion tests was used gravimetric technique andmorphological characteristics. In erosion tests used a suspension SiO2 particles indeionized water.

Low values of oxygen concentration under to 0.1 ppm of dissolved iron and less



than 2 ppm dissolved indicate that there is a tendency to form iron oxide films or some other compound. During these tests decreased component corrosionthroughout the system by injecting nitrogen gas thirty minutes before theimmersion of the sample reduce the level of runs with a flow rate 150 ml / min, asspecified by ASTM G59, achieving a final concentration of oxygen 0.1 ppm, as

measured by oxygen blisters.

After each hour of rehearsal, the steel samples cell were removed, washed indistilled water degreased with acetone, dried and placed in the desiccator for aperiod of 5 minutes, subsequently weighed on an analytical balance with sensitivityof 0.01mg. After gravimetric analysis, the specimens were cut and analyzed under a microscope.

Figure 1. Cell used for erosion tests.



Figure 2. Micrograph of high-purity silica.

EXPERIMENTAL RESULTS

Figure 3 shows that at 1000 rpm and a particle concentration of 10% byweight, there was a higher rate of erosion of steel for sizeslarger particle, this may indicate that the impact area on the surface of the material is higher, so the damage was more severe and led to a removalhigher metal. In addition, for the same rotational speed and particle size, it wasobserved that the rate of degradation of the surface increasedwith increasing particle concentration, as seen in the photomicrographs of

Figures 4and 5. In general, for concentrationsparticle 10% by weight and rotation speed of 1000 rpm, the erosion rate increasesproportionally with the particle size.



Figure 3. Erosion curves of steel AISI-SAE 1020 to 10% and 1000 ppm by weight.

Figure 4. Photomicrograph of the steel surface after the test (10% W, 50

microns, 1000rpm).

Figure 5. Photomicrograph of the steel surface after the test (30% W, 50 um, 1000 rpm).

The trend of this trial carried 30% W and 1000rpm are shown

in Figure 6, which describes the same behavior of particle concentrations 10% by



weight and 1000rpm. The erosion rate the material is greater than 150 microns at

50 microns, and Compared with the previous, is an order of magnitude higher.

For the same speed of rotation and particle size, the rate of erosion increased

with increasing concentration particles hitting the material as evidence in

micrographs of Figures 7 and 8. However, This test showed that increases speed

erosion due to increased speed rotation system. This indicates that there is a directrelationship between the erosion rate of the system and speed of rotation.

The negative rate of erosion in the early hours of test is attributed to a mass

gain of specimens steel possibly due to small scale sand particles (50 microns)

on the surfaces of same with a small amount of oxide formed (which

which is thermodynamically inevitable casualties oxygen concentrations), as

shown in time range between 0 and 3.5 hours.

Figure 6. Erosion curves AISI SAE-1020 to 30% weight and 1000 rpm.

Figure 7. Photomicrograph of the steel surface after test (10% W, 150μm, 1000 rpm).



Figure 8. Photomicrograph of the steel surface after Test 4 (30% W, 150μm, 1000

rpm).

In Figure 9 we can see that although the first hour of testing the value of speedErosion is similar for both sizes, the difference between them is significant as it passestesting time, with a larger deterioration of the material to a size of 150 microns.

Additionally, they found higher rates (maximum rate of ≈ 0.9 mg/cm2 to 150 micronsto 30% byweight and 3000rpm, a speed against≈ maximum erosion of 0.35 mg/cm2 to 10% by weight. To 50 microns, maximum speed of ≈ 0.4 mg/cm2 to 30% by weightand 3000rpm, in contrast to the speed maximum of ≈ 0.15 mg/cm2 to 10% by weightand the same rotational speed.

Figure 9. Erosion curves of steel AISI-SAE 1020 to 10% weight and 3000 rpm.



Figure 10. Steel erosion curves AISISAE 1020 to 30% by weight and 3000 rpm.

Figure 11. Photomicrograph of the steel surface after test (10% W, 50 microns, 3000 rpm).

The tests carried out at 10% W, 3000rpm and 30% W, 3000rpm, varying the particle size

have a very similar and show in Figures 9 and 10. There is a further deterioration

material for sizes of 150 micrometers can be seen in the photomicrographs of

Figures 11 through 15. The form of damage is typical of a ductile material as

is deformed by the impact of the particles.

In addition, it can be deduced that when extrapolating data variation with the concentration

of particles, notes that over time increases the speed deterioration due to the linearity in

the curves of erosion. This behavior is shown in Figure 10.

Figure 12. Photomicrograph of the steel surface after test (30% W, 50 microns, 3000 rpm).

Figure 13. Photomicrograph of the steel surface after test (10% W, 150μm, 3000 rpm).



Figure 14. Photomicrograph of the steel surface aftertest (30% W, 150μm, 3000 rpm)

Figure 15. Photomicrograph of the steel surface afterTest 9 (20% W, 100 ╣ m, 2000 rpm).

CONCLUSIONS

The erosion behavior of the steel can say that was ductile due to

the shape of observed damage as random impacts were expected as with the conditions

and operating variables. The particle velocity is more variable

system significantly, large differences in erosion rates were observed with increasing

rotational speed of the system, this can be explain since the kinetic energy of the particles is

high enough to produce strains and deterioration of plastic material. It was found that there

is a direct relationship between particle sizes studied, which means that

increasing the particle size increases erosion rate. It was established that the concentration

of particles has a slight effect on the erosion phenomenon, which can conclude that

there is a significant variable for this phenomenon.

REFERENCES

1. VINCENT, MICHAEL et al. (2004) Erosion byProppant: A Comparison of the Erosivity of S

andand Ceramic Slurry Injection and Proppants DURINGFlowback of proppant. In: SPE Ann

ual Technical Conference.

2. Peña, Dario (2001) Introduction to Erosion Materials. In: ION Magazine. Vol 17, No 1.

3. RAO, P. Veerabhadran AND BUCKLEY, DONALD.H. (1985) Characterization of solid parti



cle erosion resistance of ductile metals based in Their properties. In: Journal

of engineering for gas turbines and power. Elsevier. Vol 107, No3, pp. 669-678

4. LEVY, ALAN V. (1986) The Mechanism of platelet

erosion of ductile metals. In: Wear. Elsevier. Vol 108, pp. 1 to 21

5. FINNIE, IAIN (1960) Erosion of Surfaces by solid particles. In: Wear, Vol 3. pp. 87 to 103.

6. GOODWIN, J.E., SAGE, W. AND TILLY, M.O. (1970)Study of Erosion by Solid Particles. In: Proceedings of the Institution of Mechanical. Vol 184, pp. 279-292

7. BITTER, J. G. A. (1963) A Study of ErosionPhenomena. Part I and Part II In: Wear. Elsevi

er. Vol 6, Issue 1, pp. 5 to 21 and Vol 6, Issue 3, pp. 169 to 190.

8. STACK, M. M, JAMES J. S. AND LU, Q. (2003) Erosion

corrosion of chromium steel in a rotating cylinder electrode system: some comments of

particle size effects. In: Wear. Elsevier. Vol 256, Issue 5, pp. 557 to 564.

9. CLARK, H. M. (1991) A comparison of the erosion resistance of casing steels by sand-

oil suspensions. In: Wear. Elsevier. Volume 150, Issues 1-2, pp. 217-230

10. CLARK, H. M. (2002) Particle Size and Velocity

Slurry Erosion Effects in Laboratory Measurementsor ... do you know What Particles Are your doing?. In: Tribology International. Elsevier. Vol 35, Issue

10, pp. 617 to 624.

Received: February 2010

Acceptance Date: May 2010

determination of the erosion resistance of a carbon steel in a multi

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