1、 FORD LABORATORY TEST METHOD CA 002-01 Date Action Revisions 2001 04 30 Revised Editorial no technical change A. Cockman 1992 08 19 Printed copies are uncontrolled Page 1 of 8 Copyright 2001, Ford Global Technologies, Inc. METALLURGICAL CHARACTERISTICS OF CAST NODULAR IRON Application This procedure
2、 is used to evaluate such metallurgical characteristics of nodular irons as percent pearlite, ferrite, nodularity, type and size of carbon nodules. Equipment Required Metallurgical Cut-Off Wheel (water cooled) Band Saw Metallurgical Mount Press Or equivalent facilities to rigidly mount the specimen,
3、 if required. Metallurgical Mounting Powder Standard thermosetting mounting powder. Steel Shot (optional) Belt Sander Motor driven, equipped with #120 grind sanding belts. Metallurgical Hand Grinders Or equivalent - equipped with #1, 00, 000, 0000 emery paper or Water Wash Metallurgical Hand Grinder
4、s with 280, 320, 400 and 600 grit silicon carbide discs or adhesive backed strips. Metallurgical Polishing Wheels Polishing Media Metallograph FORD LABORATORY TEST METHOD CA 002-01 Page 2 of 8 Copyright 2001, Ford Global Technologies, Inc. Conditioning and Test Conditions All test values indicated h
5、erein are based on material conditioned in a controlled atmosphere of 23 +/- 2 C and 50 +/- 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified Procedure 1. Take metallurgical sample by sectioning part to be tested on the cut-
6、off wheel, band saw, hack saw or other convenient means. Care must be taken to avoid overheating the part during sectioning. The sample shall be taken in the area designated on the Engineering drawing or material specification. 2. If it is necessary, the sample may be metallurgically mounted. 3. Gri
7、nd the specimen on a belt sander, using 120 grit belts until the sample is flat and the surface to be examined is exposed. Care should be taken not to overheat the specimen. If water is used as a coolant, wet samples should never be ground on alumina sanding belts. 4. Hand grind the sample through t
8、he successive grades of grinding papers, rotating the sample about 90 degrees after the first paper and then back to the original position for the third paper. The fourth grinding position is the same as the second. The grinding on 1 paper should be continued until the marks of the previous operatio
9、n are removed. 5. The sample should be washed with an excess of water to remove all traces of the abrasive. 6. Rough polish on a rotating wheel covered with suitable cloth and abrasive until the sample is relatively free of any visual evidence of grinding. 7. Wash sample with alcohol to remove all t
10、races of the abrasive, rinse and blow dry with compressed air. 8. Final polish the specimen on the metallurgical polishing table, using suitable polishing cloths, abrasives and lubricants. Moderate to heavy pressure may be employed provided the sample and wheel are sufficiently wetted. For optimum n
11、odule retention, the minimum polishing time required to remove scratches is desired. 9. Flush the sample clean and dry in an air blast. 10. Etch the sample lightly in 3 % nital etchant and repolish carefully. Carry out this procedure twice to assure that if ferrite is present, it has not been smeare
12、d over the graphite nodules. FORD LABORATORY TEST METHOD CA 002-01 Page 3 of 8 Copyright 2001, Ford Global Technologies, Inc. 11. Graphite form, size and distribution may be determined in the unetched condition by projecting the microstructure on the metallograph screen at 100X. If a Dynazoom or oth
13、er type metallurgical microscope has been used it will be necessary to take photographs (100X) or use other attachments such as a calibrated reticule to determine graphite size. Figure 1 illustrates the forms of graphite. Compare the microstructure to this chart and assign a form number. Figure 2 il
14、lustrates the size of graphite nodules. Compare the size of the nodules present and assign a size number. 12. Place the grid (Figure 3) on the metallograph screen or photograph and count the number of graphite forms that are intersected by the grid. An example is illustrated in Figure 4. See Figure
15、5 for calculation of percent of graphite type. By moving the sample and projecting another section of the sample on the screen, make successive determinations on the sample until three areas of the sample have been evaluated. Calculate the percent of the graphite forms as indicated in Figure 4. If t
16、he average of 3 readings is within 10 % of the minimum requirements then a minimum of 10 readings must be made and averaged. Do not count any graphite size .80 mm in diameter and less. 13. Remove the sample from the metallograph and etch in 3 % nital etch solution. 14. Place the grid on the metallog
17、raph screen and count the number of intersections that lie in pearlite and ferrite. Calculate the percent pearlite and ferrite in a manner similar to the calculation for percent nodularity. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each
18、 party is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD CA 002-01 Page 4 of 8 Copyright 2001, Ford Global Technologies, Inc. METALLURGICAL CHARACTERISTICS OF CAST NODULAR IRON Classification of Graphite Type Figure 1 FORD LABORATORY TEST METHOD CA
19、 002-01 Page 5 of 8 Copyright 2001, Ford Global Technologies, Inc. METALLURGICAL CHARACTERISTICS OF CAST NODULAR IRON Classification of Graphite Size ( 100 X ) Figure 2 FORD LABORATORY TEST METHOD CA 002-01 Page 6 of 8 Copyright 2001, Ford Global Technologies, Inc. METALLURGICAL CHARACTERISTICS OF C
20、AST NODULAR IRON Grid Figure 3 FORD LABORATORY TEST METHOD CA 002-01 Page 7 of 8 Copyright 2001, Ford Global Technologies, Inc. METALLURGICAL CHARACTERISTICS OF CAST NODULAR IRON Calculation for % Nodularity Figure 4 FORD LABORATORY TEST METHOD CA 002-01 Page 8 of 8 Copyright 2001, Ford Global Techn
21、ologies, Inc. METALLURGICAL CHARACTERISTICS OF CAST NODULAR IRON Calculation As indicated on Figure 4, a total of 18 intersections occur when counting only Types I and II graphite. Instructions for which types are to be counted will be indicated on the Engineering drawing or in the material specification. Per Figure 4 4 (Type I) + 1 (Type II) = 5 Total Counted 18 5/18 = 28 % Figure 5
