An analysis of the solid particle erosion damage … analysis of the solid particle erosion damage...

An analysis of the solid particle erosion damage caused on AISI 304

J. R. Laguna Camacho1, A. Marquina-Chávez1, J. E. Escalante-Martínez1, C. A. Márquez-Vera2, I. Hernández-Romero2, A. Galicia-Badillo2 and M. del C. Santes-Bastián3

1 Universidad Veracruzana, Faculty of Electric and Mechanical Engineering, Av. Venustiano Carranza S/N, Col.

Revolución, C.P. 93390, Poza Rica, Veracruz, México 2 Universidad Veracruzana, Facultad de Ciencias Químicas, Av. Venustiano Carranza S/N, Col. Revolución, C.P. 93390,

Poza Rica, Veracruz, México 3 Universidad Veracruzana, Facultad de Enfermería, Blvd. Lázaro Cárdenas # 801, Col. Morelos, C.P. 93340, Poza Rica,

Veracruz, Mexico

In this chapter, erosion tests conducted to evaluate the performance and resistance of AISI 304 stainless steel in the soft annealed condition against this wear process. This material has several industrial applications such as valves, hard tools, fasteners and storage tanks. An erosion test rig based on that presented in ASTM G76-95 standard used to perform the tests. Particle size distribution analysis conducted and the silicon carbide (SiC) particles had a particle size between 350-450 µm. Tests carried out using different impact angles, 30°, 45°, 60° and 90° with a particle velocity of 24 ± 2 m/s and an abrasive flow rate of 150 ± 0.5 g/min. The room temperature during the tests was between 35°C to 40°C. Physical and mechanical properties such as density, hardness and Young´s modulus obtained for the silicon carbide and AISI 304 steel. Energy dispersive X-ray analysis (EDS) used to obtain the chemical composition of the abrasive particles and stainless steel. Scanning Electron Microscopy (SEM) images used to identify the wear mechanisms. Finally, Atomic Force Microscopy (AFM) used to compare the roughness of the surfaces before and after the tests at 45° and 60°, respectively.

Keywords: Solid particle erosion; AISI 304 Stainless steel; silicon carbide particles; high plastic deformation, fracture

1. Introduction

Solid Particle Erosion (SPE) is the progressive loss of material that results from repeated impact of small, solid particles or liquid on a surface. In some cases SPE is a useful phenomenon, as in sandblasting, abrasive deburring and high speed abrasive waterjet cutting, but it is a serious problem in many engineering systems, including stream and jet turbines, pipelines and valves carrying particulate matter [1]. In relation to erosion research on stainless steels, several authors have been working over the years. For instance, D. H. Graham [2] et al. carried out a research on the erosion resistance of candidate materials for hydraulic valves (brass, AISI 304 and AISI 440C) and hard materials (Stellite coating, boronised 440C, TiC/TiN coating) tested in a high-pressure particle impingement erosion test facility which simulates the unloader valve of a water-based hydraulic system. This valve would experience fluid moving at velocities in the region of 250 m/s and the anticipated contamination of this fluid with concentrations of 100 ppm of fine quartzite particles with sizes in the range 5-50 µm would lead to rapid erosion of components. In this work, the water contaminated with a low concentration of quartz particles. The results showed that metals presented the typical cutting erosive mode, while the erosion modes of various ceramic and cermets characterized by intergranular cracking and spallation. In addition, Z. Feng, et al. [3] performed solid particle erosion tests on four different materials such as glass, alumina, WC-7% Co and 304 stainless steel using seven erodents as steel shot, glass beads, silica, alumina, tungsten carbide, silicon carbide and diamond particles. Here, the effects of particle properties, particle shape, particle velocity and impingement angle on the erosive resistance of the materials, examined. The quantitative correlations that relate erosion damage with properties of abrasives established. On the other hand, C. T. Morrison [4] carried out erosion tests on 304 stainless steel. In this work, it concluded from the SEM observations that similar morphologies for low and high impact angles could be observed in ductile metals when they were subjected to the impact of sharp particles. The surfaces displayed a peak-and-valley topology together with attached platelet mechanisms. In addition, the physical basis for a single-mechanism to erosion in ductile metals was considered to be related to shear deformations that control material displacement within a process zone for a general set of impact events producing at all impact angles. These events included indentation, ploughing and cutting or micromachining. T. Singh, et al. [5] conducted erosion tests at room temperature to study the erosion behavior of three different stainless steels such as AISI 304, 316 and 410. In this work, three impact angles (30°, 60° and 90°) and two impact velocities (98 and 129 m/s) used. Silicon carbide (density 3100 kg/m3) employed as erodent. The general shape of the SiC particles was angular and their size was 160 µm. The results indicated that the erosion rates of 304 and 316 stainless steels were comparable while that of 410 was lower by 15%-20%. In addition, the effect of impact angle and particle velocities on the erosion rates of all the stainless steels was consistent with the ductile erosion response. The wear mechanisms identified in all three stainless steels at all impact angles and velocities, were the formation of lips and platelets and their fracture. In this chapter, the behavior and performance against erosion wear of an austenitic stainless steel AISI 304 analyzed. The main wear mechanism was

Microscopy: advances in scientific research and education (A. Méndez-Vilas, Ed.)__________________________________________________________________

1053© FORMATEX 2014

brittle fracture of large fragments and high plastic deformation, also cross-sections photographs of the erosion scars exhibited cracks on the subsurface, and material totally detached.

2. Experimental Details

2.1 Selection of materials

The material used in the tests was AISI 304 austenitic stainless steel in the soft annealed condition. In this particular case, the steel heated uniformly to temperatures between 1038 °C - 1121°C, and then cool rapidly. Mechanical applications of this material in this condition are coal hopper linings, food processing equipment, marine equipment and fasteners and valves. The specimens were ground flat with 180-grit silicon carbide paper. The roughness average value was 205 nm (Ra) with a standard deviation of 48.72 (after 10 measurements). Figure 1 shows two 3D profiles of the initial roughness obtained using an AFM (Microscope diMultimode V, Vecco, Controller diNanoscope V) on random locations of the specimen surface. The projected surface areas were 10 X 10 µm2 and 5 X 5 µm2, respectively.

a) b)

Fig. 1 3D profile of initial surface roughness, a) 248 nm b) 166 nm.

Figure 2a and b shows a micrograph of the specimen before erosion tests with different magnifications. Here, it is possible to observe the porous structure affected by the heating process. The grain boundaries are clearly defined. Figure 3 presents an EDS analysis performed to obtain the chemical composition of the tested material. In relation to the mechanical properties, the average value of the hardness in the soft annealed condition was 255 HV with a standard deviation of 39.06 (15 measurements). The applied load was 100 mN. These results obtained using a Nanoindentation Tester (TTX-NHT, CSM Instruments). In addition, the Young´s modulus obtained and the average value was 195 GPa with a standard deviation of 12.61. Figure 4 shows some Vickers indentations on AISI 304 surface on random locations.

a) b)

Fig. 2 Micrographs of 304 steel before erosion tests, a) 100X, (b) 500X.


© FORMATEX 20141054

Fig. 3 EDS analysis of stainless steel AISI 304 before erosion tests.

Fig. 4 Vickers indentations on random locations on stainless steel AISI 304. The samples had a rectangular shape with dimensions of 50 mm X 25 mm and 3 mm in thickness. The abrasive particles used were silicon carbide (SiC) with an angular shape as shown in Figure 5a. The chemical composition of the abrasive particles shows in Figure 5b. Particle size distribution obtained using an Analysette 28 image sizer. The particle size grain between 350-450 µm was the most consistent. Most particles found in this particular range. The average particle size was 342 µm with a standard deviation of 127 for the first measurement (19285 particles) shown in grey color in the graph in Figure 6. On the other hand, a second measurement (14507 particles) carried out and the average particle size was 353 µm with a standard deviation of 136 (green color). Both measurements were nearly close. The hardness of the abrasive particle is 1600 HV.



a)

b)

Fig. 5 Abrasive particle, a) Morphology of the silicon carbide particles (SiC), (b) Chemical composition of silicon carbide.

300 µm



Fig. 6 Particle size distribution.

2.2 Test procedure

The erosion tests were performed by using a rig, which based on that presented in the ASTM G76-95 [6]. The schematic diagram of the rig developed had been shown in previous erosion studies [7, 8]. In this rig, the abrasive particles were accelerated from a nozzle by using a compressed air stream that caused them to impact the surface of the material. The average particle velocity measured with an opto-electronic flight-timer similar to that described by Kosel and Anand [9, 10]. This system offers the possibility to measure the particle velocity in an accurate mode and the design does not request high costs [11]. The material eroded in a time of 10 min although each sample removed every 2 min to determine the mass loss. The impact angles used for the tests were 30°, 45°, 60° and 90°. These angles selected to evaluate the material at low and high impact angles. A particle velocity of 24 ± 2 m/s and an abrasive flow rate of 150 ± 0.5 g/min used to conduct the tests. It observed a higher interference between incident and rebounding particles at 90° [12, 13]. In all of the tests, the specimens located 10 mm from the end of the stainless steel nozzle. The nozzle had the following dimensions: 4.7 mm internal diameter, 6.3 mm external diameter and a length of 260 mm. The room temperature was between 35° C and 40° C. The specimens weighed using an analytical balance (with an accuracy of ± 0.0001 g) before the start of each test and removed every 2 min, cleaned by using acetone and weighed again to determine the amount of mass loss. Micrographs of the eroded surfaces obtained using a Scanning Electron Microscope (SEM) Quanta 3D FEG (FEI) to analyze the specimens and to identify the possible wear mechanisms°. Finally, Atomic Force Microscopy (AFM) used to compare the roughness of the surfaces before and after the tests at 45° and 60°, respectively. Profilometry also employed to measure the depth of the erosion wear scars caused on the material.

3. Results and discussion

3.1 Erosion damage at 45°

The erosion damage at all impact angles characterized by high wear debris on the surface. In this particular case, large fragments fractured by the impact action of the abrasive particles. This wear mechanism was more consistent as the impact angle increased. In relation to the wear damage on AISI 304 at 45°, the cutting action of the particles led to cause pitting and ploughing actions (grooves on the surface) which were filled by the fracture fragments after impact



and also irregular indentations where the material was only displaced, as shown in Figure 7a and b. It is assumed that the structure of the material before erosion tests (Figure 2a and b) led to high fragmentation (wear debris) on the surface due to the impact and sliding action of the abrasive particles. The lower erosion rate in all tests observed at this incident angle.

a) b)

Fig. 7 Erosion damage at 45°.

3.1.1 Cross-section of erosion scars at 45°

Cross-section photographs of the eroded surfaces obtained to analyze the wear damage in the subsurface. In Figure 8, it is possible to observe the wear scar profile with a depth of roughly 2 mm. In addition, embedded particles located on random positions on the surface are also seen. Images with higher magnification in Figure 9a and b show how the cracks on the subsurface coincided and fracture occurred. A fragment of the surface was removed by the impact and sliding action of the abrasive particles. In these photographs (Figure 9a and b), the irregularities caused by the continuous action of the particles on the eroded surfaces can be better appreciated. The two lines in the central part based on the reference line shown in the micrograph, which is equal to 1 mm.

Fig. 8 Cross-section of the erosion scar at 45°.

Fracture fragments

Ploughing action Fracture fragments

Ploughing action

1 mm

1 mm



a) b)

Fig. 9 Photographs of the cross-section at higher magnifications.

3.2 Erosion damage at 60°

In respect to the wear damage at 60°, the main wear mechanisms were high wear debris characterized by large fracture fragments which filled the grooves and pits on the surface. Plastic deformations were also observed due to the sliding action of the abrasive particles. Some wear debris was smeared or flattened on the specimen surface. The maximum erosion rate in all tests reached at this impact angle. In this particular case, a more efficient cutting action of the abrasive particles led to cause higher detachment of surface material increasing the wear damage.

a) b)

Fig. 10 Erosion damage at 60°.

3.2.1 Cross-section of erosion scars at 60°

Cross-section photographs of the eroded surface at 60° also obtained to analyse the wear damage in the subsurface. In Figure 11, it is possible to observe the wear scar profile with a maximum depth in the central part of the scar of roughly 2.1 mm. The erosion scar at this incident angle was slightly deeper than that seen at 45°. It well correlated to the maximum erosion rate, which reached at this impact angle. It confirmed with the profilometry results. In relation to the wear mechanisms, embedded particles located on random positions on the surface were also seen. Images with higher magnification in Figure 12a and b show how the cracks on the subsurface coincided and fracture occurred as observed at 45°. In this particular case, it clearly showed the high plastic deformation characterized by displaced material (this wear mechanism know in erosion wear as lips lifted in the impact and sliding direction due to the cutting action of the abrasive particles. In some places, the detachment of surface fragments was well appreciated. As presented in Figure 8, the two lines in the central part based on the reference line shown in the micrograph, which is equal to 1 mm.

Fracture fragment

Coincidient cracks on subsurface

Cracks

Coincident cracks on subsurface

Irregularities

Fracture fragments

Fracture fragments

Pits filled with wear debris

Plastic deformation Smeared or flattened

wear debris

Grooves filled with wear debris



Fig. 11 Cross-section of the erosion scar at 60°.

a) b)

Fig. 12 Photographs of the cross-section at higher magnifications.

3.3 AFM results

The 3D roughness profiles of AISI 304 after erosion tests present in Figure 13. Here, it is possible to see the grain boundaries of the microstructure before erosion tests (Figure 13a), then after tests, the modification of the surface roughness due to the impact of the silicon carbide particles at 45° and 60°, is clearly observed. In fact, the roughness value considerably increased at 60° compared to that obtained before testing. In the 3D profiles, a smoother surface observed at 45° compared to that at 60°. The average roughness obtained of five measurements carried out in different locations of each surface. The red zones in the profiles depict the deeper zones while the yellow ones the higher peaks.

(a)

High Plastic deformation (lips lifted) High Plastic deformation

1 mm

1 mm

Coincidient cracks on subsurface

Cracks

Cracks Cracks



(b)

(c)

Fig. 13 Roughness results, (a) 205 nm before erosion tests, (b) 280 nm at 45°, (c) 321 nm at 60°.

3.4 Volume loss and Total Erosion Value

The volume loss obtained dividing the mass loss (g) by the density of stainless steel AISI 304 (8.03 g/cm3). Three tests conducted for each incident angle and an average volume loss and standard deviation obtained. The maximum volume loss (mm3) reached at 60°, where the cutting and impact action of the abrasive particles caused higher detachment of material than that observed in other incident angles. On the other hand, the lower volume loss reached at 45°. The results were really close at 30°, 45° and 90°. Figure 14 shows the graph of the volume loss against the elapsed time. In all the incident angles, the volume loss increased in relation to the time.

Fig. 14 Graph Volume loss and gain (mm3) versus time (min).

0,00

20,00

40,00

60,00

80,00

100,00

120,00

140,00

160,00

0 2 4 6 8 10 12

Vol

ume

Los

s (m

m3 )

Time (min)

30° 45° 60° 90°



The total erosion value also calculated and the results present in Figure 15. It obtained dividing the volume loss (mm3) by the total mass of particles (g) that impacted the surface after 10 min as indicated in ASTM G76-95 [6]. As mentioned previously, the maximum erosion rate was at 60° followed by 90° and 30°. Here, it is possible to conclude that this material in these particular testing conditions exhibited a brittle type behavior based on the erosion literature graph presented in different erosion studies [14-16].

Fig. 15 Total erosion value versus impact angle (α).

4. Conclusions

The results presented in the discussion section allow some conclusions to be drawn in relation to the erosion behavior of AISI 304 stainless steel against the impact action of silicon carbide particles. 1. The stainless steel AISI 304 showed its maximum erosion rate at 60°. This material exhibited brittle type behavior in relation to the graph shown in the erosion literature [14], where it is possible to observe that ductile materials reach their maximum erosion rate at low impact angles (α ≥ 45°) while brittle materials display their higher erosion rate at high incident angles (α ≤ 90°). The wear rate at 45° was lower than that presented at all incident angles. 2. SEM images used to identify the wear mechanisms characterized by high fracture on the surface. In this particular case, the microstructure of the material before erosion tests was a predominant factor to observe large fracture fragments on the eroded surfaces. In addition, typical damage as pitting and ploughing action, displaced and flattened material due to subsequent impacts observed. These latter wear mechanisms are more common than the high fracture of large fragments, in stainless steels. In respect to the cross-section photographs at 45° and 60°, subsurface cracks observed. It was assumed that as these coincided, large fragments of the specimen surfaces were detached by the impact and sliding action. High plastic deformation with lifted lips around the damaged zones observed at 60°. 3. AFM examination conducted in this work, the results showed that the surface roughness increased at 45° (280 nm) and 60° (321 nm) after erosion tests compared to the initial roughness of AISI 304. The wear damage at 60° was higher than that obtained at all incident angles. In this particular case, the surface suffered higher deformation, which led to have a higher roughness variation with respect to the roughness value before the erosion tests (205 nm). The 3D profiles exhibited clearly a smoother surface at 45° than that obtained at 60°.

Acknowledgements Se reconoce el apoyo experimental del CNMN-IPN (Centro de Nanociencias y Micro y Nanotecnología) del Instituto Politécnico Nacional en la realización del trabajo presentado.

References

[1] ASM Handbook. Friction, Lubrication and Wear Technology. Vol. 18. United States: ASM International; 1992. [2] Graham DH, Ball A. Particle erosion of candidate materials for hydraulic valves. Wear. 1989; 133:125-132. [3] Feng Z, Ball A. The erosion of four materials using seven erodents – towards an understanding. Wear. 1999; 233-235:674-684. [4] Morrison CT, Scattergood RO. Erosion of 304 stainless steel. Wear. 1986; 111:1-13.

0,00E+00

1,00E-02

2,00E-02

3,00E-02

4,00E-02

5,00E-02

6,00E-02

7,00E-02

8,00E-02

9,00E-02

1,00E-01

0 10 20 30 40 50 60 70 80 90 100

Tot

al E

rosi

on V

alue

(m

m3 /

g)

Impact angle (α)



[5] Singh T, Tiwari SN, Sundararajan G. Room temperature erosion behaviour of 304, 316 and 410 stainless steels. Wear. 1991; 145:77-100.

[6] ASTM standard, G76-95 (1995), Standard practice for conducting erosion tests by solid particle impingement using gas jets, in Annual Book of ASTM Standards, Vol. 03.02, ASTM, Philadelphia, PA, 1995. p. 321-325.

[7] Vite-Torres M, Laguna-Camacho JR, Baldenebro-Castillo RE, Gallardo-Hernández EA, Vera-Cárdenas EE, Vite-Torres J. Study of solid particle erosion on AISI 420 stainless steel using angular silicon carbide and steel round grit particles. Wear. 2013; 301:383-389.

[8] Vite-Torres M, Laguna-Camacho JR, Baldenebro-Castillo RE, Gallardo-Hernández EA, Lasorsa CA, Villagrán-Villegas LY. Study of solid particle erosion on AISI D2 using angular silicon carbide and steel round grit particles. Tribology. 2014; 8:105-110.

[9] Kosel TH, Anand K. An optoelectronic erodent particle velocimeter. In: Srinivasan V, Vedula K, editors. Corrosion and particle erosion at high temperature. The minerals, Metals and Materials Society; 1989. p. 349-368.

[10] Shipway PH, Hutchings IM. Influence of nozzle roughness on conditions in a gas-blast erosion rig. Wear. 1993; 162-164:148-158.

[11] Laguna-Camacho JR. Desarrollo de un prototipo para pruebas de erosión con aire a presión y flujo de partículas, Master Thesis, SEPI–ESIME-UZ– IPN: México; 2003.

[12] Shipway PH, Hutchings IM. A method for optimizing the particle flux in erosion testing with a gas-blast apparatus. Wear. 1994; 174:169-175.

[13] Anand K, Hovis SK, Conrad H, Scattergood RO. Flux effects in solid particle erosion. Wear. 1987; 118:243-257. [14] Hutchings IM. Tribology, Friction and Wear of Engineering Materials. First ed. Cambridge: Butterworth-Heinemann; 1992. p.

171-197. [15] Laguna-Camacho JR, Marquina-Chávez A, Méndez-Méndez JV, Vite-Torres M, Gallardo-Hernández EA. Solid particle erosion

of AISI 304, 316 and 420 stainless steels. Wear. 2013; 301:398-405. [16] Stachowiak GW, Batchelor AW. Engineering Tribology. 3rd ed. UK: Butterworth-Heinemann; 2005. p. 527-542.



Date post:	08-Mar-2018
Category:	Documents
Upload:	danghanh
View:	216 times
Download:	3 times

An analysis of the solid particle erosion damage … analysis of the solid particle erosion damage...

Documents