evaluation of surface finish and its effect on packed

International Journal of Application or Innovation in Engineering & Management (IJAIEM) Web Site: www.ijaiem.org Email: [email protected]

Volume 7, Issue 6, June 2018 ISSN 2319 - 4847

Volume 7, Issue 6, June 2018 Page 77

ABSTRACT

Medium alloy carbon steel has become the choice of material for high temperature applications due to its desirable mechanical properties at elevated temperature and corrosive environment. The medium alloy carbon steel undergoes various types of corrosion like carburization, oxidation based on various industrial applications. Various methods are employed to obtain protective coating on the surface of the metal. The best suited technique among the available techniques is diffusion aluminisation using pack cementation process .The salient feature of diffusion aluminisation process is that a diffusion as well as deposition layer can be enriched on the metal surface. The Aluminizing coating technology is an established technique wherein several studies and researches are being carried out to study the kinetics of aluminisation on the metal surface. However there is lack of information and research gap regarding the role of the surface attributes and the profiles and its effect on the anti-corrosion coating thickness of the metal.This paper aims to study the role of surface roughness (Ra)on the coating thickness of the EN24 steel samples achieved by three different machining processes such as turning, grinding, abrasive flow finishing machining. The paper also investigates the influence of the surface roughness (Ra)on hardening and annealing prior to the packed diffusion aluminisation process followed by tempering of both the sets post aluminisation process. The diffusion pack cementation process was carried out at temperature of about 500 C to 900 C. The analysis was carried out to study the coating characteristics using optical light microscope, EDX using Scanning Electron Microscope (SEM), X-ray Powder Diffraction (XRD) and micro hardness. KEYWORDS – Diffusion aluminisation process, Surface roughness, Turning, Grinding, Abrasive flow finishing machining

1. INTRODUCTION Protective coatings are formed on the structural materials to ensure its use in harsher environments to avoid surface degradation due to exposure to high temperature and corrosive environment.Diffusion aluminisation is an effective surface coating technology to improve the corrosion resistance of the steel surface. Pack diffusion aluminisation is carried out at high temperatures of above (500-900 C). In Pack cementation process the pack used for aluminisation of the steel substrateconsists of aluminium source, aluminium filler and a halide activator. A number of investigations have been done to study the microstructure and phase composition of the pack diffusion aluminide coating on plain carbon steel but the role of surface finish and heat treated conditions on the growth of the aluminium on the steel substrate have not been investigated extensively.The aim of the present paper is that EN 24 steel samples is selected and is machined using turning, grinding and abrasive flow machining process. The aluminized layer, diffusion depth and phases were examined upon subjecting the sample to three different heat treatment cycles to illustrate if there exits any significant variation in the coating characteristics. 2. LITERATURE REVIEW [1] This paper titled “Low temperature pack aluminizing of X80 Pipeline steel through addition of zinc and self nano crystallization”[ ],authors WANG Yu,HUANG Min and XIE Xiang Xu carried out packed diffusion aluminisation

EVALUATION OF SURFACE FINISH AND ITS EFFECT ON PACKED DIFFUSION

ALUMINISATION OF LOW ALLOY STEEL COMPONENT Sreenath S1, M.R. Shivakumar2

1P.G Scholar, Department of Industrial Engineering, Ramaiah Institute of Technology, Bengaluru, Karnataka, India.

2Assistant Professor, Department of Industrial Engineering, Ramaiah Institute of Technology, Bengaluru, Karnataka, India.

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carried out on pipeline X80 steel wherein the surface of the pipeline steel was modified using surface refinement treatment and variation in the pack powder. [2] This paper titled “A LOW TEMPERATURE ALUMINIZING TREATMENT OF HOT WORK TOOL STEEL” [ ], author Bozidar matijevic carried out Aluminisation on X40CrMoV5-1 hot work tool steel using pack cementation process. The Aluminizing temperature was carried out at 550°C to 620 °C. Investigation was carried out study the role of temperature and time on the phase change and microstructure of the component. [3] This paper titled “Pack Diffusion Aluminizing of Carbon Steel”[ ]author M.E Abd EL-AZIM,K.E MOHAMED.....F.H HAMMAD.This paper shows that aluminisation diffusion is best achieved through pack cementation process. The aluminisation process was carried out through the use of ferrous aluminium mixture, pure aluminium and halide activator. Diffusion aluminisation was carried out on delta 37 steel. [4]This paper titled “Lower temperature aluminizing and its effect on improving corrosion resistance of iron treated by surface mechanical attrition treatment”[ ] authors Cheng Zhong,Wenbin Hu,Yiming Jiang ,the study involved use of an Fe plate to create a nano surface finish of 28nm using surface mechanical attrition treatment. The (SMAT) samples were analysed for their coating thicknesses using SEM, XRD. The result highlighted that the samples subjected to SMAT process were highly corrosion resistant and the samples subjected SMAT samples achieved good coating thickness at lower temperature. [5] This paper titled “The aluminizing in powder technology of AISI 304 steel” [ ] authors DB baitanu,DG Galusa...Bakri Abdullah,this paper presents studies about the aluminisation carried out on AISI 304 steel to form protective coatings to reduce corrosion resitance under harsh environments. Pack cementation mixture consisted of pure aluminium powder, aluminium oxide and an halide activator. The analysis was carried out using SEM to understand the layer composition after aluminisation at various degrees. [6]This paper titled “Aluminide coating on 304 Stainless steel”[ ] authors Kevin L. Smith,Armen kutyan,Shaghik A.Abolian,…Vilupanur A.ravi,this paper studies about aluminisation were type 304 stainless steel was used under the temperature of 650°C,750°C,850°C for time range of one to twenty five hours using pack cementation technique. 3. PROBLEM OBJECTIVE • Selection of the protective coating process to avoid corrosion on the low alloy steel component. • Establishing the standard cycle to achieve the desired coating characteristics. • Selection of the desired grade of carbon steel to achieve the protective coating. • Study and compare the influence of surface finish on the coating thickness of the material. • Study and compare the role of surface finish and coating thickness on the hardness of the material. • Analyse the hardness values before and after aluminisation. • Analyse the coating parameters like strength of the chemical bond, phase’s changes in the inter-metallic layer using SEM, XRD. • Draw interferences and conclude from the above. 4. Experimental procedure The EN24 samples having an outer diameter of 30 mm and inner diameter of 15mm with a thickness of 15mm was produced using turning, grinding and abrasive flow machining process. The samples were cleaned and one set of sample was subjected to hardening and annealing cycle according to the fig 1.The hardness were measured in the stock condition and after hardening and annealing.All the samples(hardened and non-hardened) are aluminized according to the cycles as shown in figure 2 .The aluminizing agents consisted of Ferro –aluminium powder, aluminium powder and activator(NH4Cl).Upon completion of the aluminisation cycle the samples(hardened and non-hardened) are subjected to hardening and tempering as shown in the figure3.






Figure 1Heat Treatment cycle before aluminisation process

Fig 2 Heat treatment cycle for aluminisation process

Fig 3Heat Treatment Cycle after aluminisation process

The EN24 samples after the completion of the three different cycles are measured for their coating thicknesses using optical light microscope,EDX in SEM for percentage atomic weight ,phases obtained using XRD and hardness using micro hardness tester.

RESULTS AND DISCUSSIONS The hardness values of the rods before hardening and after subjecting it to hardening cycle is given in the table below.

Tab 1 hardness values of the samples Specimen Hardness Values (HRC)

Non hardened and annealed 16.22

Hardened and annealed 30.24






Coating thicknesses of samples (After aluminisation process): The coating thickness of the samples subjected to aluminisation process are measured using optical light microscope at 200X magnification. The results obtained from the instrument are tabulated below.

Tab 2 Coating thicknesses of samples after aluminisation Sample 6 Thicknesses (µm) Turning non hardened 85.06 Grinding non hardened 85.55 AFFM non hardened 92.68 Turning hardened 99.06 Grinding hardened 87.36 AFFM hardened 92.85

Turning non -hardenedGrinding non -hardenedAFFM non- hardened

Turning hardenedGrinding hardenedAFFM hardened

Fig 4: At 200X various sample coatings Coating Thickness discussion The coating thickness was measured using optical light microscope and the analyses revealed there was not much significant difference in the coating quality of the turned, grinded and abrasive flow machined samples. The coating results also did not show any variation and almost remained the same between the hardened and non-hardened. Hardness measurement: The following results contain all the hardness values measured by Vickers hardness test. This was done on EN24 material before and after coating process.The report contains micro hardness values. The hardness is measured by Vickers hardness method. For the measurement of Vickers hardness 300gf is used.

Tab 3 Micro hardness (After aluminisation coating): Samples Hardness values (HRC) Turning non hardened 29.49 Grinding non hardened 30.46 AFFM non hardened 30.27 Turning hardened 31.45






Grinding hardened 32.27 AFFM hardened 31.62

3 SEM, EDX ANALYSIS The hardened and non hardened samples are analysed for their percentage compositional atomic weight using Energy Dispersive X-ray Analysis(EDX) technique. The results of the percentage atomic weight of the various spectra are summarized below. Tab----- compares the( EDX ) of the hardened and non hardened samples subjected to different machining proecsses.

[a] [b]

Fig 5EDX analysis of turned samples of [a] Non-hardened sample [b] Hardened sample

[a] [b]

Fig 6 EDX analysis of grinded samples of [a] Non-hardened sample [b] Hardened sample

[a] [b]

Fig 7 EDX analysis of abrasive flow finished samples of [a] Non-hardened sample, [b] Hardened sample






Tab4 EDX analysis

EDX analysis discussions The percentage atomic weight analysis was carried out in SEM using EDX method . The comparisons exhibited that as one moves from outer end one spectrum to the interface layer of the spectrum band the percentage atomic weight of the alumium decreases showing no major highlighting differences in the hardened and non-hardened samples after the aluminisation process and also the surface roughness's.

XRD ANALYSIS

Fig 8 XRD analysis of the samples

XRD analysis discussions: Theanalysis carried out in XRD revealed that no major highlighting differences in the hardened and non-hardened samples wherein the samples were enriched with rich phases of AlFe3 and the surface of the non-hardened sample was containing Al2O3 .Further studies and thorough analysis needs to be carried out to differentiate highlighting differences in the samples. CONCLUSION The EN24 steel is prone to corrosion like carburization, oxidation, sulfudation based on type of industrial applications over passage of time. These undesirable effects can be avoided by incorporating protective coatings on the surface of the steel . Various methods are employed to obtain protective coating on the surface of the metal. The area of interest is overcome the above problem .To find a solution for the problem exhaustive literature survey has been carried out by






selecting the best suited technique among the available protective coating techniques. The existing solution to overcome the above problem is achieved by pack cementation aluminisation process. The experimental setup and procedure for carrying out the pack cementation aluminisation process is defined. The area of focus is the role of surface finish and heat treatment conditions on the growth and coating characteristics of the aluminized samples. The varying degree of surface finish is produced by turning, grinding and abrasive flow finishing process. The samples are subjected to three different heat treatment cycles to achieve the aluminium coating. The pack cementation mixtures are selected based on exhaustive literature survey. The Aluminium coating achieved on the surface of the EN24 samples was in the range of 80-100 µm .The aluminized samples after the completion of the heat treatment samples were analysed for the coating characteristics using optical light microscope, EDX using SEM,XRD and micro hardness. The analysis and comparison results out of the optical light microscope, EDX using SEM, XRD and micro hardness revealed no significant differences in the coating characteristics. It was also found that the hardened, non-hardened samples and the surface roughness's had no effect on the aluminisation process. Further studies and researches on corrosion resistance using salt spray technique needs to be carried to distinguish the reliability of the samples so as to conclude between the three different machined samples. References [1]Y. Wang et al., "Low-Temperature Pack Aluminizing of X80 Pipeline Steel through Addition of Zinc and Surface

Self-Nano crystallization", Advanced Materials Research, Vols. 233-235, pp. 2516-2521, 2011 [2] Božidar Matijević ISSN 1333-1124 A LOW TEMPERATURE ALUMINIZING TREATMENT OF HOT WORK

TOOL STEEL UDC 621.785: 669.14.018:620.179.11 [3]Abd El Azim, M. E.Vol 12, No 1 (1994)meatallurgical sciencesand technology - ArticlesPack diffusion

aluminizing of Carbon Steel [4] Cheng Zhong,Wenbin Hu,Yiming Jiang,Bo Deng,Jin Li,Journal of Coatings Technology and Research,January

2011, Volume 8, Issue 1, pp 107–116| C,Lower temperature aluminizing and its effect on improving corrosion resistance of iron treated by surface mechanical attrition treatment

[5] The aluminizing in powder technology of AISI 304 steelD B Băitanu1, D G Găluşcă1, D C Achiţei1,2, M G Minciună1,2 and Mohd Mustafa Al Bakri Abdullah2Published under licence by IOP Publishing Ltd

[6] Journal of Materials ScienceOctober 1994, Volume 29, Issue 20, pp 5424–5428| Cite asThe effect of diffusion barrier formation on the kinetics of aluminizing in inconel-718 diffusion profiles for material like aluminium, iron and nickel.

[7]Aluminide Coatings on 304 Stainless SteelKL Smith, A Kutyan, SA Abolian, TF Krenek… - CORROSION …, 2013 - onepetro.org, Yuki Matsuoka1, Yasuo Matsunaga1, Kiyokazu Nakagawa1, Yoshihiro Tuda1 and Shigeji Taniguchi2 ,Growth Behavior of Coatings Formed by Vapor Phase Aluminizing Using Fe-Al Pellets of Varying Composition 1Research Laboratory, Ishikawajima-Harima Heavy Industries Co., Ltd., Yokohama 235-8501, Japan



evaluation of surface finish and its effect on packed

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