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fbtwitterlinkedinvimeoflicker grey 14rssslideshare1
Languages: English
Types: Doctoral thesis
Subjects: Q1, QC, QA76
The main aim of this project was to quantitatively characterise the developed surface\ud topography of finishes on stainless steel sheet using three-dimensional surface analysis\ud techniques.\ud At present surface topography is measured using (mainly) stylus profilometry and analysed with\ud 2D parameters, such as Ra, Rq and Rz. These 2D measurements are not only unreliable due to\ud a lack of standardised measurement methodology, but are also difficult to relate directly to the\ud actual shape of the topography in 3 dimensions. They bear little direct relation to the functional\ud properties of the surface of stainless steel, making them less useful than their 3D counterparts.\ud Initially it is crucial to ensure that the surface topography data collected is correct, accurate and\ud relevant, by defining a measurement strategy. Models of the surface topography are developed\ud encompassing the usual features of the topography and variations in the topography caused by\ud production or 'defects'. The functional features are discussed and predicted relevant parameters\ud are presented.\ud The protocol covers the selection of the correct measuring instrument based on the surface\ud model and the size of the relevant functional features so that the desired lateral and vertical\ud resolution and range is achievable. Measurement data is then analysed using Fast Fourier\ud Transforms (FFTs) to separate the different frequencies within the spatial frequencies detected\ud on the surface. The frequency of the important features shows up dominantly on a Power\ud Spectral Density (PSD) plot and this is used to find the correct sampling interval to accurately\ud reconstruct the 3D surface data. The correct instrument for further measurements is then\ud selected using a Steadman diagram. Operational details of the measuring instruments available\ud for this project are given and variables for these instruments are discussed. Finally,\ud measurement method recommendations are made for each of the four finishes modelled.\ud Based on this surface characterisation an attempt is made to identify the 3D parameters that\ud give a quantitative description of common stainless steel sheet finishes with respect to some\ud aspects of their production and functional performance.\ud An investigation of the differences in manufacturing processes, gauge and grade of material is\ud presented, providing an insight into the effect on topography of such divergences. The\ud standardised 3D parameter set is examined to determine its sensitivity to common variations in\ud the topography of the 2B finish and therefore their potential relevance.\ud A new data separation technique of the material probability curve for use on the 3D datasets\ud establishes a cut-off (transition point) between the two main functionally relevant features of the\ud 2B surface (plateaus and valleys) by finding the intersection of the asymptotes of a fitted conic\ud section, giving a non subjective methodology to establish the section height. The standardised\ud 3D parameters are then used on the separated data, with the aim of being more functionally\ud relevant to the main surface studied.\ud Functional tests to rate capability of these parameters in the areas of optical appearance,\ud lubricant retention and corrosion are carried out and the appropriate topography parameters are\ud related to their performance.
  • The results below are discovered through our pilot algorithms. Let us know how we are doing!

    • Chapter 1 Introduction ........................................................................... 1 1.1 Introduction .....................................................................................................1 1.2 Overall Aims & Objectives ..............................................................................1 1.2.1 Aims .....................................................................................................1 1.2.2 Objectives.............................................................................................2 1.3 Thesis Layout ..................................................................................................2 1.3.1 Chapter 3 The 'Functional' Surfaces......................................................2 1.3.2 Chapter 4 Measurement Strategy..........................................................2 1.3.3 Chapter 5 The Effects of Variations in Production..................................3 1.3.4 Chapter 6 Optical Appearance ..............................................................3 1.3.5 Chapter 7 Lubricant Retention...............................................................3 1.3.6 Chapter 8 Corrosion..............................................................................3 1.3.7 Chapter 9 Summary of Discussions.......................................................4 1.3.8 Chapter 10 Conclusion..........................................................................4
    • Chapter 7 Lubricant Retention .............................................................. 131 7.1 Summary of the Chapter .................................................................................131 7.2 Introduction .....................................................................................................131 7.3 Drip Tests ........................................................................................................132 7.4 Initial Trials ......................................................................................................134 7.4.1 Results..................................................................................................134 7.4.1.1 Optimisation of Method..............................................................134 7.4.1.2 Sensitivity of Method..................................................................135 7.4.1.3 Initial Conclusions Concerning the Methodology ........................135 7.5 2B Trials...........................................................................................................136 7.5.1 Study of Methodology............................................................................136
    • Chapter 8 Corrosion ............................................................................... 146 8.1 Summary of the Chapter ................................................................................. 146 8.2 Introduction ..................................................................................................... 146 8.3 Collaborative Research ................................................................................... 146 8.4 Developed Methods of Assessing Corrosion Susceptibility ......................... 147 8.4.1 The ZRA Method ................................................................................... 147 8.4.2 The Potentiostatic Method ..................................................................... 150 8.4.3 Discussion and Conclusions of Method Development ............................ 151 8.5 Results ............................................................................................................. 152 8.6 Discussion ....................................................................................................... 156 8.7 Conclusions..................................................................................................... 158
    • Chapter 10 Conclusion ............................................................................. 162 10.1 Conclusions .................................................................................................. 162 10.2 Contributions to Knowledge ......................................................................... 166 10.3 Suggested Further Work ............................................................................... 167
    • Measurements of 2B Stainless Steel', Proceedings 8th International Conference on Metrology
    • and Properties of Engineering Surfaces, 2000
    • Appendix 2 2D Ra Values .............................................................................. 184
    • Appendix 3 Distinctness of Image and Haze Graphs............................................ 186
    • Appendix 4 2D Parameters ............................................................................ 189
    • Appendix 5 3D Parameters ............................................................................ 192
    • Figure 3.1: Axonometric and contour interferometer images of white hot band stainless steel topography .........................................................................................................53
    • Figure 3.2: High magnification Scanning Electron Microscope image of white hot band stainless steel topography ..................................................................................54
    • Figure 3.3: SEM and interferometer images of 2B surface finish on stainless steel showing relatively flat plateaus and matrix of valleys ..........................................56
    • Figure 3.4: SEM and AFM images of a 2B surface finish on stainless steel showing plateau micro-roughness ....................................................................................57
    • Figure 3.5: The developed model of the 2B surface finish.....................................................58
    • Figure 3.6: Interferometer images of the BA surface finish on stainless steel showing the effects of processing...........................................................................................59
    • Figure 3.7: The developed model of the BA surface finish ....................................................60
    • Figure 3.8: Interferometer images of a brushed finish on stainless steel showing unidirectional troughs and ridges ........................................................................61
    • Figure 3.9: SEM images of a brushed surface showing remnant 2B features........................62
    • Figure 3.10: The developed model of a brushed surface finish ...............................................62
    • Figure 4.1: SEM images showing plateaus and valleys on 2B at x5k & x10k magnifications ....................................................................................................71
    • Figure 4.2: Profile of surface with reconstruction at high frequency limit of 1500 mm-1 and PSD plot for surface frequencies ........................................................................73
    • Figure 4.3: The reconstructed surfaces at frequencies of 2500 mm-1 and 3125 mm-1 with contour map showing area used.........................................................................73
    • Figure 4.4: Comparison of frequency limits and effect on accuracy of profile reconstruction.....................................................................................................74
    • Figure 4.5: 2D profile and axonometric plot showing plateaus, boundaries and spiky features..............................................................................................................74
    • Figure 4.6: Graph of Sm (Material Volume) against Modulation Threshold (for x50 mag.) ......76
    • Figure 4.7: Graph of Sv (Valley Void Volume) against Modulation Threshold (for x50 mag.).....................................................................................................76
    • Figure 4.8: Graph of Vvv (Volume of Voids in the Valley Zone) against Modulation Threshold (for x100 mag.) ..................................................................................77
    • Figure 4.9: Graphs of (a) Sq, Root-Mean Square Deviation and (b) Sz, Ten Point Height, against Modulation Threshold (for x50 and x100 mags.) .....................................78
    • Figure 5.1: Graph of Sq (Root Mean Square Deviation) against nominal thickness for all grades................................................................................................................93
    • Figure 5.2: Graph of Sz (Maximum Height of Texture surface) against nominal thickness for all grades ...........................................................................................................93
    • Figure 5.3: Graph of Sv (Maximum Valley Height) against nominal thickness for all grades ...94
    • Figure 5.4: Graph of functional volume parameters against nominal thickness for all grades................................................................................................................94
    • Figure 5.5: Profiles of the thickest and thinnest samples from Source 2................................95
    • Figure 5.6: Graph of S5z (Ten Point Height of surface) against nominal thickness for all grades................................................................................................................95
    • Figure 5.7: Graph of Sa (Arithmetic Average Roughness) against nominal thickness for all grades................................................................................................................96
    • Figure 5.8: Graph of Sq (Root Mean Square Deviation) against actual measured thickness for 316 and 304 grades ......................................................................................97
    • Figure 5.9: Graph of Sz (Maximum Height of Texture surface) against actual measured thickness for 316 and 304 grades .......................................................................97
    • Figure 5.10: Graph of Sv (Maximum Valley Height) against actual measured thickness for 316 and 304 grades ...........................................................................................98
    • Figure 5.11: Graph of functional volume parameters, Vmp (Material Volume of the Texture surface) and Vvv (Valley Void Volume of the Texture surface) against actual measured thickness for 316 and 304 grade ........................................................98
    • Figure 5.12: Graph of functional volume parameters, Vmc (Core Material Volume of the Texture surface) and Vvc (Core Void Volume of the Texture surface) against actual measured thickness for 316 and 304 grades ............................................99
    • Figure 5.13: Graph of S5z (Ten Point Height of surface) against actual measured thickness for 316 and 304 grades ......................................................................................99
    • Figure 6.1: Panaspect Appearance Meter ......................................................................... 111
    • Figure 6.2: Graph of Gloss (Gls) against Sq (Root Mean Square Deviation) ....................... 113
    • Figure 6.3: Graph of Specular Reflectance (Rs) against Sq (Root Mean Square Deviation)........................................................................................................ 114
    • Figure 6.4: Graph of Haze (Hz) against Sq (Root Mean Square Deviation)......................... 115
    • Figure 6.5: Graph of distinctness of image (DOI) against Sq (Root Mean Square Deviation)........................................................................................................ 115
    • Figure 6.6: Graph of Average Ssc (Arithmetic Mean Peak Curvature) against Average Gloss (Gls) ...................................................................................................... 116
    • Figure 6.7 Graph of Average Ssc (Arithmetic Mean Peak Curvature) against Average Specular Reflectance ...................................................................................... 117
    • Figure 6.8: Graph of Average Sdr (Developed Interfacial Area Ratio) against Average Specular Reflectance ...................................................................................... 117
    • Figure 6.9: Bearing Area curve of 2B surface showing main data regions .......................... 119
    • Figure 6.10: Material Probability curve showing 5 main regions (taken from [78])................. 119
    • Figure 6.11: Transition point on Material Probability curve................................................... 120
    • Figure 6.12: MatLabâ„¢ GUI ................................................................................................. 121
    • Figure 7.1: Shape of the sample for drip testing................................................................. 132
    • Figure 7.2: New Rig set-up for drip testing......................................................................... 133
    • Figure 7.3: Graph showing repeatability of test with 25 drops of oil applied........................ 134
    • Figure 7.4: Graph showing the sensitivity of the test using the 2B and BA finishes............. 135
    • Figure 7.5: Graph showing variation of retained oil across four samples ............................ 136
    • Figure 7.6: Graph showing variation of retained oil in relation to direction .......................... 137
    • Figure 7.7: Graph of Sq (Root Mean Square Deviation) for a) all the data and b) the separated valley data against % of oil retained ................................................ 138
    • Figure 7.8: Graph of Sp (Maximum Peak Height) for the separated valley data against % of oil retained ...................................................................................................... 139
    • Figure 7.9: Graph of Sds (Density of Summits) for the separated plateau data against % of oil retained ...................................................................................................... 140
    • Figure 7.10: Graph of Vmp (Material Volume of the Texture surface) for the separated valley data against % of oil retained........................................................................... 141
    • Figure 7.11: Graph of Vmc (Core Material Volume of the Texture surface) for the separated valley data against % of oil retained................................................................. 142
    • Figure 7.12: Graph of Vvv (Valley Void Volume of the Texture surface) for the separated valley data against % of oil retained................................................................. 143
    • Figure 8.1: Theory of ZRA method .................................................................................... 147
    • Figure 8.2: ZRA cell setup................................................................................................. 148
    • Figure 8.3: Recording of current peaks from metastable pitting.......................................... 148 in (a) 0.03M NaCl and (b) 0.01M FeCl3........................................................................................... 149
    • Figure 8.5: The relationship between number of pits on 304 SS in 0.03M NaCl and 0.01 M FeCl3 and grit number of surface finish............................................................. 150
    • Figure 8.6: Potentiostatic method setup............................................................................. 150
    • Figure 8.7: Examples of potentiostatic measurements showing metastable pits with an applied potential of 100 mV/SCE ..................................................................... 151
    • Figure 8.8: The relationship between the average number of pitting events for 304 SS in 0.03M NaCl solutions and applied potential ..................................................... 151
    • Figure 8.9: Graph of Sq (Root Mean Square Deviation) against corrosion susceptibility ..... 154
    • Figure 8.10: Graph of Sz (Maximum Height of Texture surface) against corrosion susceptibility.................................................................................................... 154
    • Figure 8.11: Graph of Vvc (Core Void Volume of the Texture surface) against corrosion susceptibility.................................................................................................... 155
    • Table 2.1: Definitions of designated finishes [3].....................................................................9
    • Table 2.2: Main areas of past research ...............................................................................13
    • Table 2.3: Types of gloss [14] .............................................................................................18
    • Table 2.4: Field set of 3-D parameters [65]..........................................................................47
    • Table 2.5: Description of DIN 4776 parameters (adapted from [41]) ....................................49
    • Table 4.1: Instrument Capabilities .......................................................................................67
    • Table 4.2: Data collected from SEM study for a 2B finish.....................................................71
    • Table 4.3: 3D parameters set with potential relationships ....................................................82
    • Table 4.4: Data collected from SEM study for a brushed finish ............................................83
    • Table 4.5: Data collected from SEM study for WHB surface ................................................85
    • Table 5.1: Average parameters for 316 and 304 grade materials...................................... 100
    • Table 5.2: Average parameters for 316 and 304 grade materials (2 to 6 mm) ................... 101
    • Table 6.1: Hypothesised relationship between new parameters and appearance characteristics ................................................................................................. 118
    • Table 6.2: Suggested parameter set for optical specification ............................................ 130
    • Table 7.1: Suggested parameter set for lubricant retention............................................... 145
    • Table 8.1: Unidirectional samples .................................................................................... 153
    • Table 8.2: Differences between sample preparation methods related to 3D surface topography parameters ................................................................................... 156
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