1、 FORD LABORATORY TEST METHOD EU-CA 002-01 Date Action Revisions 2001 04 30 Revised Editorial no technical change A. Cockman 2000 03 07 Revised Editorial no technical change A. Cockman 1994 02 28 Printed copies are uncontrolled Page 1 of 8 Copyright 2001, Ford Global Technologies, Inc. METALLOGRAPHIC
2、 ANALYSIS OF NODULAR CAST IRON Scope This procedure defines the method for evaluating metallographic haracteristics such as graphite form and size, nodularity and percentages of gases present in the microstructure of nodular graphite cast iron. Definition Nodularity Unless otherwise stated, nodulari
3、ty is defined as the percentage of graphite particles which are of Type I in the microstructure. Equipment Required 1. Cut-off machine. 2. Metallurgical mounting press and media. 3. Metallurgical hand grinders or grinding machines. 4. Metallurgical polishing wheels and media. 5. Metallurgical micros
4、cope. Conditioning and Test Conditions All test values indicated herein 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. Sampling When t
5、aking specimens from the castings, attention must be paid to the location, to the wall thickness, to the distance from the surface and to the presence of chilling and other defects. The location of the surface examined should be carefully recorded in any report. FORD LABORATORY TEST METHOD EU-CA 002
6、-01 Page 2 of 8 Copyright 2001, Ford Global Technologies, Inc. Preparation The area of polished surface must be greater than 1 square cm in order to obtain a true representation of the graphite distribution within the section. Care must be taken when grinding and polishing not to overheat the sample
7、 or distort or dislodge the graphite particles, in order that they appear in their true form and size. If any evidence of poor preparation is apparent, the sample must be reground and polished. At least 80 % of the nodule sites must retain their graphite. Examination of the graphite under the micros
8、cope is usually carried out on the unetched polished section, whilst subsequent etching (e.g. 2 percent Nital or Picral) is necessary for evaluation of the remainder of the microstructure. Microscopic Examination The entire polished area shall be scanned, at a magnification of 100X. Measurements may
9、 be made either directly from the image projected on a ground glass screen, or from a photomicrograph of the specimen, or by use of a calibrated eyepiece. The graphite forms present are identified by reference to Figure 1, which represents the forms of graphite generally found in nodular cast iron.
10、The graphite size is then determined by reference to Figure 2, which is based on the maximum dimension of the largest particles. If more than one form is observed, the percentage of each should be reported. Nodule Count The nodule count is determined by counting the number of nodules or particles of
11、 other form which appear within a 100 mm square at a magnification of 100X. The average for a minimum of 5 different fields is calculated and the result expressed in nodules per square mm. Nodularity Nodularity is determined by counting the number of spheroidal particles which occur within a 100 mm
12、square at a magnification of 100X and calculating these as a percentage of the total number of graphite particles within the square. A minimum of five different fields will be examined. More fields will be examined where variation in first five results indicates heterogeneity. The proportion of othe
13、r graphite forms will be calculated on a similar basis when required. Particles of 0.8 mm or less (at 100X magnification) on their major axis are not counted. Percentage Ferrite Cementite and Pearlite The percentage of ferrite, cementite and pearlite in the microstructure are determined as follows:
14、At a magnification of 100X a count is made of the number of ferrite, cementite and pearlite areas which coincide with inter-sections on the grid. If 1 particle coincides with two intersections it is counted as 2, since one is assessing relative areas. At least 10 different fields are analyzed and th
15、e percentage of each phase calculated as demonstrated in Figure 3. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD EU-CA 002-01 P
16、age 3 of 8 Copyright 2001, Ford Global Technologies, Inc. METALLOGRAPHIC ANALYSIS OF NODULAR CAST IRON Fig. 1 Reference Diagram for Graphite Form FORD LABORATORY TEST METHOD EU-CA 002-01 Page 4 of 8 Copyright 2001, Ford Global Technologies, Inc. METALLOGRAPHIC ANALYSIS OF NODULAR CAST IRON FORD LABO
17、RATORY TEST METHOD EU-CA 002-01 Page 5 of 8 Copyright 2001, Ford Global Technologies, Inc. METALLOGRAPHIC ANALYSIS OF NODULAR CAST IRON FIG. 2 Reference Diagram for Nodule Size at 100X Magnification. Nodule counts are shown as examples and no relationship can be assumed between nodule size and count
18、. FORD LABORATORY TEST METHOD EU-CA 002-01 Page 6 of 8 Copyright 2001, Ford Global Technologies, Inc. METALLOGRAPHIC ANALYSIS OF NODULAR CAST IRON FORD LABORATORY TEST METHOD EU-CA 002-01 Page 7 of 8 Copyright 2001, Ford Global Technologies, Inc. METALLOGRAPHIC ANALYSIS OF NODULAR CAST IRON FIG. 3 E
19、xample: Typical Analysis of a Microstructure The diagram represents the first of ten fields which are analysed as demonstrated in Table 1. FORD LABORATORY TEST METHOD EU-CA 002-01 Page 8 of 8 Copyright 2001, Ford Global Technologies, Inc. METALLOGRAPHIC ANALYSIS OF NODULAR CAST IRON Table 1 Example: Typical Analysis of a Microstructure ANALYSIS OF FIELD NO. 1 Phase Line No. Field No. 1 10 Fields 1 2 3 4 5 6 7 8 9 10 Ferrite Cementite Pearlite - - 10 1 - 8 - - 10 2 - 7 1 - 9 - - 9 - - 10 - 1 7 - - 9 1 - 9 5 1 87 48 11 873 % Ferrite = 48 = 5 % 10 % Cementite = 11 = 1 % 10
