1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
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3、ublication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/standards.sae.org/J911_201704 SURFACE VEHICLE RECOMMENDED PRACTICE J911 APR2017 Issued 1965-01 Reaffirmed 1986-06
5、 Revised 2017-04 Superseding J911 MAR1998 Surface Texture, Roughness (Ra), Peak Count(Pc), and Mean Profile Spacing, (Rsm) Measurement of Metallic Coated and Uncoated Steel Sheet/Strip to be Formed and/or to be Painted RATIONALE The industry needs to update the spec to reflect use of zinc and alumin
6、ized coated steels. New non contact methods of measurement are also being used which are now applicable to the measurement methods employed. A number of new parameters that are being investigated to further quantify surface texture and the impact on steel perfromance in the auto industry may also ne
7、ed to be added to this document. 1. SCOPE 1.1 This SAE Recommended Practice describes a method for measuring Roughness Average (Ra) and Peak Count (PC) and other variables of the surface of metallic coated and uncoated steel sheet/strip. 1.2 The method includes a system for equipment configuration,
8、calibration, and procedures for determining average surface roughness, Ra (m), average peak count, PC (peaks per cm) and mean profile spacing, Rsm on metallic coated and uncoated steel sheet/strip surfaces. This specification is based on metric measurements, English measurements are approximations o
9、nly 2. REFERENCES 2.1 Applicable Document The following publication forms a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. 2.1.1 ASME Publication Available from ASME, P.O. Box 2900, 22 Law Drive, Fairfield, NJ
10、07007-2900, Tel: 800-843-2763 (U.S./Canada), 001-800-843-2763 (Mexico), 973-882-1170 (outside North America), www.asme.org. ASME B46.1-2009 Surface Texture SAE INTERNATIONAL J911 APR2017 Page 2 of 11 3. DEFINITIONS 3.1 STYLUS PROFILOMETER: The stylus profilometer is a device which scans a surface wi
11、th a diamond tip to measure the surface texture. The stylus tip geometry and other aspects of the instrumentation limit the shortest spatial wavelength that can be measured (typically about 1m). The length of travel of the stylus and other aspects of the instrumentation limit the longest spatial wav
12、elength that can be measured (typically about 25 mm). 3.2 TRAVERSING LENGTH: The full length over which the stylus profilometer is scanned along the surface. 3.3 EVALUATION LENGTH: The length contained within and typically shorter than the traversing length over which the evaluation of the surface t
13、exture parameters is performed 3.4 BEST FIT MEAN LINE: A line that defines the nominal profile so that within the Evaluation Length the sum of the squares of the difference between the profile and this line are minimized. 3.5 SPATIAL WAVELENGTH CONTENT: The surface texture profile may be considered
14、as being composed of a spectrum of sinusoidal components each with a given wavelength and amplitude. The measurement of the surface texture typically returns a wide bandwidth (e.g., 1 m 15 mm) of spatial wavelength components. The various spatial wavelength components may affect different functional
15、 characteristics of the texture. For example, relatively shorter wavelength structures (e.g., 1.0 mm) may better correlate with paint appearance. 3.6 ROUGHNESS LONG-WAVELENGTH CUTOFF, C: The Roughness Long Wavelength Cutoff establishes the lengths of spatial features which are attenuated prior to an
16、alysis of the various surface roughness parameters. Based on the use of the default Gaussian filter as described in ASME B46.1-2009, the amplitude of the spatial wavelength components at c are attenuated by 50% before roughness parameter determination. The amplitude of spatial wavelength components
17、greater than c are further attenuated such that spatial wavelength components greater than c provide minimal contribution to the evaluation of the various roughness texture parameters. 3.7 ROUGHNESS SHORT-WAVELENGTH CUTOFF, S: The Roughness Short Wavelength Cutoff establishes the lengths of spatial
18、features which are attenuated prior to analysis of the various surface roughness parameters. Based on the use of the default Gaussian filter as described in ASME B46.1-2009, the amplitude of the spatial wavelength components at s are attenuated by 50% before roughness parameter determination. The am
19、plitude of spatial wavelength components less than s are further attenuated such that spatial wavelength components less than s provide minimal contribution to the evaluation of the various roughness texture parameters. 3.8 SAMPLING LENGTH The evaluation length is subdivided into shorter segments pr
20、ior to analysis defined to be the Sampling Length. The length of these segments is typically equal to the Roughness Long-Wavelength Cutoff, c. A measurement of the surface texture profile may be made over many contiguous sampling lengths. Typically 5 sampling lengths or more are used for analysis pe
21、r stylus trace. SAE INTERNATIONAL J911 APR2017 Page 3 of 11 3.9 ANALYSIS SPATIAL WAVELENGTH BANDWIDTH The Analysis Spatial Wavelength Bandwidth consists of the spatial wavelength components greater than the Roughness Short-Wavelength Cutoff, s and less than the Roughness Long-Wavelength cutoff c. 3.
22、10 ROUGHNESS AVERAGE, Ra: The arithmetic average of the absolute values of the profile height deviations recorded within the evaluation length and measured from the mean line (Figure 1). 3.11 PEAK COUNT The peak count (PC) is the number of peaks per unit length (peaks/cm or peaks/in). 3.12 MEAN PROF
23、ILE SPACING, Rsm: The mean value of the spacing between texture profile crossings of the mean line. As specified in ASME B46.1 2009 the evaluation of Rsm involves default profile feature height discrimination and default spacing discrimination that are adopted for this measurement protocol (Figure 2
24、). Rsm is evaluated over the total evaluation length. dxxZR L en g thE va lu a tio na )( Figure 1 - Demonstration of the calculation of the Roughness Average, Ra. -1 .0 0-0 .5 00 .0 00 .5 01 .0 01 .5 0X A x isZ(x)0 .0 00 .5 01 .0 01 .5 0X a x isZ(x)Evaluation Length Best Fit Mean Line Surface Textur
25、e Profile Absolute Value of the Surface texture Profile SAE INTERNATIONAL J911 APR2017 Page 4 of 11 niiSmnR s m1Figure 2 - Demonstration of the calculation of the Mean Profile Spacing, Rsm. 3.13 PEAK A surface irregularity wherein the roughness profile intersects consecutively a lower and upper boun
26、dary line. The boundary lines are located parallel and equidistant from the roughness profile mean line. The vertical distance between these boundary lines is termed the peak count level. 3.14 PEAK COUNT LEVEL The vertical distance in micrometers (or micro-inch) between the boundary lines described
27、in the definition of “Peak“, (see Error! Reference source not found.). The standard value for the peak count level is 1.25 m (nominally 50 in). Known as Peak count level (PCL) see diagram below: Sm1 Sm2 Sm4 Sm4 Sm3 Best Fit Mean Line Evaluation Length SAE INTERNATIONAL J911 APR2017 Page 5 of 11 Figu
28、re 3 - Peak counting 4. EQUIPMENT, TEST CONDITIONS, AND MATERIALS (Ra AND Pc) 4.1 A stylus type surface roughness and peak counting instrument (profilometer) or equivalent. Figure 4 4.2 The instrument shall comply with specifications for stylus type instruments as detailed in section 4.4 of the Amer
29、ican National Standard: ASME B46.1-2009; namely: a. The nominal stylus tip radius shall be 10 m (nominally 400 in) or smaller. The stylus tip radius must be identified in the report b. The static stylus force (for a 10 m stylus) shall not exceed 0.016 N at any point within the displacement range of
30、the stylus, and the minimum stylus force shall be sufficient to maintain contact with the surface. (The maximum recommended stylus force will be lower for a smaller stylus radius; as tabulated in section 3.3.5.2 of ASME B46.1 2009 c. The response of the phase correct Gaussian filter used to process
31、the profile signal (or the profile data) shall comply with the attenuation characteristics and limits stated in section 9.5 (of ASME B46.1-2009). H eig h tS en so rS k idd ed S ty lus P rof ilomet erSAE INTERNATIONAL J911 APR2017 Page 6 of 11 4.3 The instrument shall be calibrated in terms of averag
32、e roughness (Ra) using a precision reference specimen having a nominal Ra value in the measurement range (typically 0.25 to 2.5 m or nominally 10 to 100 in, for all metallic coated and cold-rolled steel surfaces). 4.4 The roughness long-wavelength cutoff,c for average roughness and peak count measur
33、ements on metallic coated, cold and hot rolled steel sheet surfaces shall be 0.8 mm (nominally 0.03 in). The roughness short-wavelength cutoff,s for average roughness and peak count measurements on metallic coated, cold and hot rolled steel sheet surfaces shall be 2.7 m (nominally 100 in). 4.5 The v
34、alue for the peak count level (Figure 3) shall be 1.25 m (nominally 50 in). 4.6 The value for the traverse length (measurement length) shall be 7 times the roughness long-wavelength cutoff, c or “integrated roughness profilometers“. Integrated roughness profilometers (recommended for use here) compu
35、te the roughness properties from a stored electrical waveform representing the profile upon completion of a surface scan over the traverse length. Most modern profilometers are of this type. Continuously averaging profilometers continuously compute, update, and display roughness properties as the st
36、ylus scans the traverse length. Use of these profilometers adds more constraints on the instruments response time, speed, and indicated device characteristics (sections 4.4.3 and 4.4.4 of ASME B46.1 2009). 4.7 The instrument shall exclude from assessment, a short segment of the traverse length at bo
37、th ends to ensure that mechanical and electrical transients at the beginning and end of the profile are excluded from the measurement. The segment length shall be no longer than one cutoff length to ensure that at least five cutoff lengths are used for assessment. 4.8 Sample material selected for me
38、asurement shall be representative of the material as produced. The area tested should be at least 50 mm (2 in) from the mill coil edge. Samples for sheet examination shall be identified as to rolling direction, suitably flat, and the sample size large enough to run the tests. (A convenient size is 1
39、50 mm (nominally 6 in) long, and 100 mm (4 in) wide, with the longer dimension parallel to the direction of rolling.) 4.9 Optional Equipment, Test Conditions, Rsm and Stylus Instrument Configuration for surfaces to be painted a. A Skidless Stylus device Figure 5 H eig h tS en so rS k idl ess S ty lu
40、s P rof ilomet erSAE INTERNATIONAL J911 APR2017 Page 7 of 11 b. A 2 m or 5 m stylus radius c. A Stylus Force of 0.0007 N max for 2 m stylus, 0.004 N max for 5 m stylus d. An Evaluation Length at least 5X the chosen roughness long-wavelength cutoff e. A Traversing Length at least 6X the chosen roughn
41、ess long-wavelength cutoff 4.10 Analysis Configuration a. A Gaussian filter as per ASME B46.1 2009 b. A chosen, Roughness Short-Wavelength Cutoff, s c. A chosen Roughness Long-Wavelength Cutoff, c d. A sampling length equal to the Roughness Long-Wavelength cutoff. e. A minimum of 5 sampling lengths
42、5. TEST PROCEDURE FOR RA AND PC 5.1 Preparation The following items should be inspected to insure proper operation of the measuring equipment: a. Prepare the instrument for use according to the manufacturers instructions. b. Set the traverse length to a minimum 5.6 mm (nominally 0.21 in) for an (Lon
43、ger traversing lengths for either type of profilometers are preferred and permissible.) c. Set the cutoff length roughness long-wavelength cutoff to 0.8 mm (nominally 0.03 in). roughness short wavelength cutoff to 2.7m (nominally 100 in) d. Set the peak count level to 1.25 m (nominally 50 in). e. Ch
44、eck the suitability of location. The suitability of location can be checked by observing the roughness reading obtained on a smooth piece of flat glass. A reading or 0.05 m (nominally 2 in) or less indicates the location is suitably vibration free. f. Allow ample warm-up time after powering-up the i
45、nstrument and before performing measurements. g. Inspect the test sample to ensure it is free from burrs, scratches, and foreign particles. Deburr, identify a scratch-free test location, and wipe with a soft lint-free cloth to remove all oils. SAE INTERNATIONAL J911 APR2017 Page 8 of 11 5.2 Calibrat
46、ion of instruments are typically performed with the use of precision reference specimens as per ASME B46.1-2009-Section 11. There are four types of reference specimens used to calibrate an instrument. The Type A specimens are typically some type of step or groove that is used to calibrate the accura
47、cy of the height measurement. Type B specimens are comprised of different features such as a knife edge or series of finely spaced structures which determine the stylus condition/tip size. Type C and Type D specimens are used to verify measurement of known texture parameters (e.g., Ra) being compris
48、ed of either periodic profiles (Type C) or irregular profiles (Type D). All of the precision reference specimens may be certified by secondary calibration facilities or directly by NIST. 5.3 Calibration Calibration frequency and procedure should be performed based on manufacturers instructions/recom
49、mendations of the individual equipment used, and on the pattern of use as defined by the laboratory quality system (e.g., heavy use of the instrument might necessitate more frequent calibrations). Calibration is performed per the recommended procedures provided by the instrumentation manufacturer. Typically the calibration includes a measurement of a Ra stand
