NAVISTAR CEMS AT-1-2001 Ultrasonic Steel Cleanliness Test.pdf

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1、 This document is restricted and may not be sent outside International Truck and Engine Corporation or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. Ga42001 International Truck and Engine Corporation. OCTOBER 2001 Page 1 of 7

2、 INTERNATIONAL TRUCK AND ENGINE CORPORATION CEMS (CORPORATE ENGINEERING MATERIAL SPECIFICATION)NUMBER: CEMS AT-1 TITLE: Ultrasonic Steel Cleanliness Test CURRENT ISSUE DATE: October 2001 WRITTEN/REVIEWED BY: Materials Engineering APPROVED BY: Materials Engineering SUPERSEDES ISSUE OF: July 1999 PRIN

3、TED COPIES OF THIS DOCUMENT MUST BE VERIFIED FOR CURRENT REVISION This specification may involve hazardous materials, equipment, and procedures. This specification does not purport to address all of the safety issues associated with its use. The user is responsible to consult appropriate safety and

4、health practices and to determine the applicability of regulatory limits prior to use. Change Notice: Editorial Changes 1.0 SCOPE This method covers a procedure for rating steel cleanliness by means of an automatic computerized ultrasonic system. The test is performed on a volumetric rather than a s

5、urface examination basis and thus inherently has a much greater capability of providing reliable inclusion content information. The system provides for detecting and counting various size inclusions. It consists of an ultrasonic test instrument, a search unit, a means of recording signals, reference

6、 test blocks and an immersion tank with suitable scanning facilities. Pulsed sound waves penetrate the steel sample through a fluid coupling and upon encountering a discontinuity such as a nonmetallic inclusion, are reflected with an energy level dependent upon the defect area and contour. The refle

7、cted ultrasound is sorted into 16 evenly spaced categories or inclusion size levels and counted. The computer calculates a cleanliness index which is based upon the percentage of counts in each category multiplied by an empirical weighting factor for each category. 2.0 APPARATUS 2.1 Sperry Model UM7

8、21 Reflectoscope with pulse Receiver Unit Model 10N and Transigate E550. 2.2 Automation Industries search unit Type SIL, Style 50A 2248, inch (19.05) 5 MHz. 2.3 Digital Equipment Corporation, A-D Converter Model AF-1, Computer Model PDP 8/I, Analog Digital Interface as designed by International. 2.4

9、 Immersion tank with suitable scanning and indexing equipment. 3.0 MATERIAL TEST SPECIMENS 3.1 Specimen Size Specimens will be rolled or forged to a 4 in (102 mm) or 5 in (127 mm) square with sufficient length to scan at least 6 inches (152 mm). NUMBER: CEMS AT-1 TITLE: Ultrasonic Steel Cleanliness

10、Test CURRENT ISSUE DATE: October 2001 This document is restricted and may not be sent outside International Truck and Engine Corporation or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. Ga42001 International Truck and Engine

11、Corporation. OCTOBER 2001 Page 2 of 7 3.2 Surface Finish Requirements The test surface (surface through which the sound energy enters the sample) is normally machine-finished to within 0.38 in (9.5 mm) of the sample edges. This surface will have a surface finish of preferably not less than 14in (0.3

12、6m) nor more than 77 in (1.96 m) AA in any direction over the surface. 3.3 Thermal Treatment Thermal conditioning of sample is required to minimize acoustic anomalies. Treatment of medium and low alloy steel samples consists of normalizing at 160F (71C) (nominal) above the Ac3 Transformation Tempera

13、ture for one to two hours at heat. 4.0 PROCEDURE 4.1 Calibration and Operation 4.1.1 Counter A count is recorded in one of the 16 evenly spaced categories with each transmitted pulse. This provides a sampling rate equal to the pulse repetition rate of the pulse generator. If no signal is evident, co

14、unts will occur in Category 1. An electronic counter or analog/digital converter is used. It is essential to synchronize the counter with the analog output signal to assure that sampling occurs during peak voltage period and does not occur during signal rise time, fall time or at a quiescent voltage

15、 state. The block diagram of a computerized ultrasonic system is shown in Figure 1. 4.1.2 Sensitivity Setting To determine the sensitivity setting for inspecting a selected gated depth, a reference step block (or individual blocks) is required which contain 0.015 in (0.38 mm) diameter flat bottom ho

16、les. Metal travel to the holes will coincide dimensionally with the metal path that is traveled from the entry surface to gate center. A reference step block is shown in Figure 2. 4.1.2.1 The reference step block is required to be made from the material to be tested or that which is acoustically sim

17、ilar. Reference standards will be prepared of premium quality vacuum degassed material which has been inspected ultrasonically to verify cleanliness. 4.1.2.2 Instrument sensitivity will be set by aligning the 5 MHz search unit over a 0.015 in (0.38 mm) diameter flat bottom hole in applicable gated r

18、ange to allow proper water path. The sensitivity control is adjusted to obtain a 2.0 in (51 mm) video amplitude on a cathode ray tube. 4.1.2.3 The highest order counter (Category 16) must be adjusted (interface sensitivity control) to respond to a video amplitude signal of 2.0 in (51 mm) with an out

19、put voltage corresponding to the midpoint of the upper level range. The lower order counter is adjusted via interface offset control to respond to a video amplitude signal of 0.2 in (5 mm) with an output voltage as determined by the following relationship: Low Level Voltage = 0.2 x high Level Midpoi

20、nt Voltage 2 4.1.2.3.1 This adjustment must be made after warm up before operating the equipment. NUMBER: CEMS AT-1 TITLE: Ultrasonic Steel Cleanliness Test CURRENT ISSUE DATE: October 2001 This document is restricted and may not be sent outside International Truck and Engine Corporation or reproduc

21、ed without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. Ga42001 International Truck and Engine Corporation. OCTOBER 2001 Page 3 of 7 4.1.2.4 Water Path: The proper water path for a 5 MHz transducer is 2.000 0.015 in (50.80 0.38 mm) and the wat

22、er path for a 10 MHz transducer is 1.000 0.015 in (25.40 0.38 mm). The water temperature will be 67 to 78F (19 to 26C). 4.2 Miscellaneous Requirements 4.2.1 Scanning will be parallel to rolling direction. 4.2.2 Pulse repetition rate will be 750 pulses/second. 4.2.3 Scanning speed will be 6.0 in/sec

23、(150 mm/sec). 4.2.4 Lateral indexing will be 0.050 in (1.3 mm). See Figure 3. 4.2.5 Gated inspection zones will consist of three regions as indicated in Figure 3. Other gated zones may be inspected upon agreement between purchaser and supplier. 5.0 COMPUTATION AND REPORTING OF TEST RESULTS 5.1 All d

24、ata accrued on number of various inclusion sizes at the termination of the scan is mathematically treated by the computer to obtain a cleanliness index rating. x Cleanliness Index Rating = FP n=1Where F = Percent of counts occurring for each category P = Weighting factor for each category P 5.1.1 Fo

25、r example, the following test results are reported and mathematically treated as indicated: Category Count Level Number of Count % Counts Weighting Factor Product 1 N1N1/NtA A (N1/Nt) 2 N2 2/NtB B (N2/Nt) 15 N15 N15/NtO O (N15/Nt) 16 N16N16/NtP P (N16/Nt) Cleanlines Index Rating + - + P (N16/Nt) (Nt

26、= Total Number of Counts) NUMBER: CEMS AT-1 TITLE: Ultrasonic Steel Cleanliness Test CURRENT ISSUE DATE: October 2001 This document is restricted and may not be sent outside International Truck and Engine Corporation or reproduced without permission from Corporate Technical Standards. Suppliers are

27、required to assume all patent liability. Ga42001 International Truck and Engine Corporation. OCTOBER 2001 Page 4 of 7 5.2 The following series of weighting factors will be used to calculate a cleanliness index rating. Category Number Weighting or Progression Factors, 1.62 n-2 1 0.6 2 1.0 3 1.6 4 2.6

28、 5 4.3 6 6.7 7 11.2 8 18.1 9 29.3 10 47.4 11 76.9 12 124.5 13 201.7 14 326.7 15 529.3 16 857.5 5.3 Bracket Inspection of Steel Ingots 5.3.1 A bracket inspection procedure will be used unless otherwise specified by the controlling product engineering department. Ultrasonic cleanliness indices will be

29、 determined from the top and bottom of the first, middle and last ingots. Inspection zones noted above will consist of three regions as indicated in Figure 3. Thus each heat meeting the required cleanliness will have a minimum of 2 x 3 x 3 or 18 cleanliness indices, none of which may exceeds the max

30、imum index, that billet will be diverted to less critical use and the next adjacent billet tested. This will be continued until all cleanliness indices meet the required index. 5.3.2 Any excessive or unusual amounts of nonmetallic inclusions or defects visually noted outside the automatically record

31、ed areas will be carefully reviewed by responsible personnel. Any ingot with Category 16 indications should be considered for diversion to other use. 5.3.3 The Cleanliness Index Rating reported will be based upon a 4 in (102 mm) square billet. If a 5 in (127 mm) square billet is tested, the measured

32、 index will be proportionately reduced by multiplying by a factor of 16 in2/25in2(103 cm2/161 cm2) or 0.64. For example, a Cleanliness Index Rating of 7.8 measured on a 5 in square will be reported as an equivalent Cleanliness Index Rating of 5 for a 4 in square. NUMBER: CEMS AT-1 TITLE: Ultrasonic

33、Steel Cleanliness Test CURRENT ISSUE DATE: October 2001 This document is restricted and may not be sent outside International Truck and Engine Corporation or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. Ga42001 International

34、 Truck and Engine Corporation. OCTOBER 2001 Page 5 of 7 NUMBER: CEMS AT-1 TITLE: Ultrasonic Steel Cleanliness Test CURRENT ISSUE DATE: October 2001 This document is restricted and may not be sent outside International Truck and Engine Corporation or reproduced without permission from Corporate Techn

35、ical Standards. Suppliers are required to assume all patent liability. Ga42001 International Truck and Engine Corporation. OCTOBER 2001 Page 6 of 7 Size of Test Specimen Dimensions A B C D in mm in mm in mm in mm in mm 4.0 102 2.7 70 2.0 51 1.3 33 0.5 12.7 5.0 127 3.5 89 2.5 64 1.5 38 0.5 12.7 Figur

36、e 2 Reference Calibration Standard (Steel Stop Block) for Adjusting Sensitivity at Various Gated Levels 4.0 or 5.0 in (102 or 127 mm) Test Specimens NUMBER: CEMS AT-1 TITLE: Ultrasonic Steel Cleanliness Test CURRENT ISSUE DATE: October 2001 This document is restricted and may not be sent outside Int

37、ernational Truck and Engine Corporation or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. Ga42001 International Truck and Engine Corporation. OCTOBER 2001 Page 7 of 7 Dimensions Size of Test SpecimenDimension A B C in mm in mm in mm 4 102 0.62 16 1.0 25 5 127 0.88 22 1.3 38 Figure 3 Gated areas of Inspection and Scanning Patterns for Ultrasonic Method