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 3.4, 4 1977 09 28 Released SM/EQ8261 TP Printed copies are uncontrolled Copyright 2009, Ford Global Technologies, LLC Page 1 of 4 TUFFTRIDING -
2、REQUIREMENTS SS-M99A9001-A NOT TO BE USED FOR NEW DESIGN 1. SCOPE The process defined by this specification is a molten salt bath, based on cyanates and carbonates with a small amount of cyanide - generally less than 5%. This produces a wear, scuff and seizure resistant single phase compound layer E
3、 - FexN on ferrous metal surfaces. 2. APPLICATION This process is used in the manufacturing of camshafts for engines which are induction hardened or chilled on the cam profiles. 3. REQUIREMENTS 3.0 STANDARD REQUIREMENTS FOR PRODUCTION MATERIALS Material suppliers and part producers must conform to t
4、he Companys Standard Requirements For Production Materials (WSS-M99P1111-A). 3.1 INDUCTION HARDENED COMPONENT 3.1.1 Process Requirements 3.1.1.1 Bath Temperature 570 - 610 C 3.1.1.2 Bath Composition The guidelines given by the supplier have to be met. 3.1.1.3 Cooling Cool in a cooling bath on a hydr
5、oxide basis at a temperature of at least 350 C, optionally use water or oil at approx. 80 C. 3.1.2 Requirements to the Finished Part: 3.1.2.1 Thickness of Compound Layer: 0,008 - 0,018 mm, measured by metallographic method at analyzable areas, whereby the influence of graphite and carbide is disrega
6、rded. 3.1.2.2 Porosity of Compound Layer: The porosity is measured at analyzable areas, whereby the influence of graphite and carbide is disregarded. The porous zone must not exceed 50% of the measured layer thickness. ENGINEERING MATERIAL SPECIFICATIONSS-M99A9001-A Printed copies are uncontrolled C
7、opyright 2009, Ford Global Technologies, LLC Page 2 of 4 3.2 CHILLED COMPONENT 3.2.1 Process Requirements 3.2.1.1 Cleaning Prior to treatment, parts must be cleaned to remove oil, grease or scale. 3.2.1.2 Preheating Parts to be preheated in normal atmosphere to 350 400 C for a minimum of 30 minutes
8、and a maximum of 120 minutes at temperature. 3.2.1.3 Bath Composition The process is such that a bath, containing cyanate and cyanide salts, is heated in a titanium or titanium lined or special alloy (nickel base) pot to a specified temperature. Bath composition CNO 33.00 - 39.00% CN max. 5.00% Feto
9、t max. 0.02% Control limits for analysis Cyanate 34.00 - 38.00% 3.2.1.4 Nitriding temperature The treatment temperature should be maintained at 575 - 585 C. When a new load is introduced into the bath, the temperature shall not fall below 540 C and recovery from 540 C to operating temperature 580 C
10、shall not exceed 30 minutes. 3.2.1.5 Nitriding time The treatment time required depends upon the material and the nitride layer specified. Normally it is 90 minutes at temperature or otherwise is specified on drawing. 3.2.1.6 Cooling after nitriding Slow cooling following nitriding is essential to a
11、void cracking of chilled areas of the component. Cool in a vacuum-cooling-station designed to minimize oxidation of the surface. Vacuum of 100 mbar or better has to be generated in less than two (2) minutes. Parts to be maintained under vacuum until temperature is below 350 C and further cool down i
12、n air to below 100 C. The cooling station, cooling time and load weight shall be in accordance to the requirements. ENGINEERING MATERIAL SPECIFICATIONSS-M99A9001-A Printed copies are uncontrolled Copyright 2009, Ford Global Technologies, LLC Page 3 of 4 3.2.1.7 Washing Following cooling parts to be
13、washed in hot water at min 60 C for a time sufficient to remove salts. Note: Care must be taken to ensure that all salts are removed from blind holes. 3.2.2 Requirements of the finished parts 3.2.2.1 Thickness of layer Thickness and porosity shall be measured by metallographic method at analyzable a
14、reas. The measurement has to be carried out at the reference position as the front end slotted flange or otherwise specified positions showing on drawing according to para. 3.2.2.2. mean compact layer min. 0.002 mm mean compound layer 0.008 0.018 mm Although not used for determining layer thickness,
15、 a microsection through any cams must show observable compact layer in all matrix areas at the contact surface. 3.3 EVALUATION OF LAYER THICKNESS (See para 5 for preparation method) The surface being examined must be viewed between 500 to 1000 x. Take an overview at random and measure layer thicknes
16、s from the compact layer/base metal interface in accordance with “Definitions“. Take 6 (six) fields of view at 1000 x Magnification. Within each field, measure the highest and lowest compound layer depth. Compact layer to be measured at the same point. Porous layer determined by difference. Mean val
17、ues taken on the twelve readings obtained of each layer. Note: A suitable point for measurement is defined as all functional areas of view with no mechanical edge damage or mount/surface gapping and layer discontinuity due to graphite or carbon, shall be ignored. 5. SAMPLE PREPARATION 5.1 Materials
18、and apparatus required 1. Cut-off machine with cooling equipment 2. Edge support materials (eg. copper or aluminum foil or electroless plating facility). 3. Mounting press and mounting media 4. Grinding machine 5. Grinding paper, grades 240 - 800 6. Polishing machine 7. Diamant polishing compound 8.
19、 Dry air blast 9. Nital etch solution (1%) 10. Metallurgical microscope Capable of magnifying at up to 1000 X with measuring facility ENGINEERING MATERIAL SPECIFICATIONSS-M99A9001-A Printed copies are uncontrolled Copyright 2009, Ford Global Technologies, LLC Page 4 of 4 5.2 DEFINITION Compound Laye
20、r The sum of compact layer and porous layer. The layer thickness should be measured from the compact layer/base metal interface to the surface of the specimen. Compact Layer The layer thickness from the compact layer/base metal interface to the point where porosity is visible at up to 1000X magnific
21、ation. Porous Layer The surface layer which is usually determine by subtracting compact layer thickness from compound layer thickness. 5.3 PROCEDURE The sample must be cut at 90 to the surface to be measured. The cut surface of the microsection on which the nitrided case depth is to be determined, m
22、ust be ground and polished to a sufficient fine finish to permit etching and highlighting of the compound layer. All precautions must be taken to prevent cracks and rounding of edges. The following procedure is recommended. The test sample should be electroless plated (copper or nickel) or tightly w
23、rapped in an edge support foil (copper, tin, aluminum) prior to mounting in diallyl phthalate based resin with glass fiber reinforcement or equivalent low shrinkage, high hardness mounting compound. The grinding operation should be carried out on automatic grinding equipment or carefully on manual e
24、quipment. The cold worked zone should be removed by grinding off approx. 2 mm in the first operation. Subsequent operation should be in line with good metallographic practice using 240 - 800 grit paper and 6 micron, 3 micron and 1 micron diamond compounds. The residual diamond compound should be carefully removed prior to etching. (e.g. ultrasonic cleaner) Etch in 1% Nital.
