1、 FORD LABORATORY TEST METHOD AA 101-03 Date Action Revisions 2000 08 07 Editorial no technical change A. Cockman 2000 03 07 Editorial no technical change A. Cockman 1996 05 03 Printed copies are uncontrolled Page 1 of 2 Copyright 2000, Ford G lobal Technologies, Inc. DETERMINATION OF CARBON POTENTIA
2、L USING SHIM STOCK Application This test method describes a procedure for determining the carbon potential of the atmosphere in a heat treating furnace. Steel shim stock samples are processed through the furnace with the work being heat treated and subsequently analyzed for carbon content. An altern
3、ative procedure that may be used involves locating the sample in the furnace in such a manner to permit removal prior to extraction of the load. For deep - case carburizing appl ications, FLTM AA 101 - 04 “Determination of Carbon Gradient Using Test Bars“ shall be used. Apparatus Required Carbon Ana
4、lyzer Leco Carbon Determinator. Source: Leco Corporation 3000 Lakeview Avenue St. Joseph, MI 49085 Telephone: (616) 983 - 5531 (or fro m local Leco agents) Scissors Analytical Balance Precision of +/ - 0.1 mg and a 25 g minimum capacity. Materials Required Shim Stock 0.10 to 0.15 mm SAE 1010 (0.30 -
5、 0.60 % Mn) steel shim stock. Source: DE - STA - CO Shim Stock Fa Aichelin Industrieofen Bau DeStaCo Division, Dover Corp. 7014 Kornwestheim P.O. Box 2800, 250 Park St. West Germany Troy, MI 48007 Telephone: (313) 539 - 2008 Wire Soft iron or copper wire. Deionized or Distilled Water 20 micromhos/cm
6、 at 250 C maximum conductivity (ASTM D 1 125). FORD LABORATORY TEST METHOD AA 101-03 Page 2 of 2 Copyright 2000, Ford Global Technologies, Inc. Acid Solution* 5 % hydrochloric acid in water. CAUTION: Corrosive. Solvent* Mineral spirits or Stoddard solvent. CAUTION: Low flash point. * Refer to Indust
7、rial Hygiene for health and safety comments. Conditioning and Test Conditions All tes t 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 u
8、nless otherwise specified. Procedure 1. C ut a sample from shim stock approximately 50 mm long. 2. Pierce hole in sample and affix with wire to a part or fixture ready for entry into furnace. 3. Retrieve shim sample after heat treatment and quenching but prior to tempering. Sample must remain i n he
9、at treatment zone long enough to reach equilibrium with the atmosphere. 4. Wash sample in mineral spirits to remove quenchant. Clean sample in 5 % hydrochloric acid solution to remove any light surface oxide. Avoid excessive etching to prevent smut formation. 5. Trim sample to appropriate size for c
10、arbon analysis as specified by the carbon analyzer manufacturer. Weigh sample on analytical balance and record weight. 6. Perform carbon analysis in accordance with the carbon analyzer manufacturers in structions. 7. The percent carbon content of sample is equal to carbon potential of atmosphere. Al
11、ternative Procedure For some furnace installations, it may be preferable to insert the shim through the furnace wall into the atmosphere through an access tube. Examples where the alternative procedure would be used would be with batch furnaces in which the sample cannot be retrieved prior to temper
12、ing, or in carburizing or carbonitriding processes with diffusion cycles at carbon potentials substantially l ower than the primary cycle. The shim sample must be quenched immediately upon removal from the access tube. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determin ing proper use and handling in its facilities.
