1、 ENGINEERING MATERIAL SPECIFICATIONDate Action Revisions 2009 03 26 N-STATUS No Replacement Named L. Sinclair, FNA 2005 02 04 Revised Inserted 3.0; Deleted 3.1, 3.8, 4 1972 03 29 Released Released for 5000 pieces CG-7737-SP Printed copies are uncontrolled Copyright 2009, Ford Global Technologies, LL
2、C Page 1 of 2 CARBONITRIDING OF FINGER FOLLOWERS SS-M99A9000-AA NOT TO BE USED FOR NEW DESIGN 1. SCOPE This specification outlines the approved method for producing a wear resistant surface on nodular cast iron parts to specification S-M1A4524-A by a carbonitriding process. The process consists of h
3、eating the clean, properly spaced parts to a specified temperature in an ammonia enriched carburising atmosphere, holding the parts at the specified temperatures until the required depth of the carbonitrided zone is reached (as specified on blue-print) and quenching to obtain the required surface ha
4、rdness. 2. APPLICATION This specification was released originally for use on finger followers. 3. REQUIREMENTS 3.0 STANDARD REQUIREMENTS FOR PRODUCTION MATERIALS Material suppliers and part producers must conform to the Companys Standard Requirements For Production Materials (WSS-M99P1111-A). 3.2 CA
5、RBONITRIDED ZONE Diffusion zone on the surface. The depth is measured perpendicular to the surface where the carbonitrided zone contrasts with the matrix. (Etching with 2 - 3% Nital, recommended magnification 200 X). 3.3 FURNACE The carbonitriding is to be carried out in a seal quench-gas atmosphere
6、 batch type, radiant tube furnace equipped to heat uniformly within the range of 780 - 900 C. 3.4 CLEANING After jigging and immediately prior to carbonitriding, parts and jigs are to be thoroughly cleaned in a hot alkali cleaner. Parts and jigs must be dry and must not be handled or allowed to beco
7、me contaminated in any way before charging into furnace. PROCESS - Use P3 T 308 cleaner or approved equivalent. 3.5 FURNACE ATMOSPHERE This is to be composed of reacted fuel gas enriched with propane (C3H8) and anhydrous ammonia to give a C-potential of 0.7 - 1.1% and an N-potential of 0.7 - 1.1%. T
8、his is to be checked according to FLTM EU-BA 054-01 during process stage 1. The dew point to be aimed at during operating cycle shall be 0 C. ENGINEERING MATERIAL SPECIFICATIONSS-M99A9000-AA Printed copies are uncontrolled Copyright 2009, Ford Global Technologies, LLC Page 2 of 2 3.6 HEAT TREAT CYCL
9、E A two-stage process, typical gas atmosphere for each stage is shown under paragraph 5, General Information. STAGE 1 A minimum of 1 h 45 mins at 820 C. Cycle time to commence when both temperatures and required dew point have been achieved. STAGE 2 Temperature is to be raised to 860 C for 10 to 15
10、mins and at the same time the ammonia volume is to be reduced. The temperature of stock must be allowed to equalise at 860 C before the start of the 10 to 15 minute stage. This will take approximately 20 mins. 3.7 QUENCHING Quench directly in well agitated oil. The temperature is to be selected to s
11、uit the particular operating conditions (type of oil) to give the required blue-print hardness with complete freedom from cracking. 5. GENERAL INFORMATION The information given below is provided for clarification and assistance in meeting the requirements of this specification. Recommended furnace atmosphere for a furnace with a chamber size of 900 x 1200 x 600 mm. Carrier gas 25 m3/hour Ammonia Stage 1 1.6 m3/hour Ammonia Stage 2 0.5 m3/hour Propane at commencement of cycle and then depending on dew point 0.83 m3/hour
