1、 ENGINEERING MATERIAL SPECIFICATION Material Name Specification Number Date Action Revisions 2002 07 24 Revised Updated and Renumbered 1991 12 12 C10181734 Released W. Jones/N. Riley EAO/C Webster NAAO Printed copies are uncontrolled Page 1 of 5 Copyright 2002, Ford Global Technologies, Inc. STEEL W
2、IRE, VALVE SPRING, CHROMIUM WSD-M1A260-B1 VANADIUM ALLOY STEEL WIRE, VALVE SPRING, CHROMIUM WSD-M1A260-B2 VANADIUM ALLOY, DRESSED SURFACE 1. SCOPE The material defined by this specification is an oil hardened and tempered chromium-vanadium alloy high quality steel spring wire. In general, steels sha
3、ll be specially melted and processed to give a clean steel of uniform core and surface qualities to meet the quality requirements of this specification. 2. APPLICATION This specification was released originally for valve springs subjected to high stresses at moderately increased working temperatures
4、. 3. REQUIREMENTS 3.1 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 CHEMICAL COMPOSITION, weight % Carbon 0.60 - 0.75 Manganese 0.50 - 0.90 Phosphorus 0.030 max Su
5、lphur 0.025 max Silicon 0.15 - 0.30 Chromium 0.40 - 0.60 Vanadium 0.10 - 0.25 Oxygen * Aluminum * * The oxygen and aluminum contents shall be recorded as part of the control plan. Optional material see para 4.1. Specific composition limits, melting and casting practice, rod, wire and heat treatment
6、processing route to meet performance and manufacturing requirements will form part of an agreed control plan for each spring component. ENGINEERING MATERIAL SPECIFICATION WSD-M1A260-B1/B2 Page 2 of 5 Copyright 2002, Ford Global Technologies, Inc. 3.3 MECHANICAL PROPERTIES (ASTM E 8M, as delivered fo
7、r spring manufacture) Wire Diameter, mm Ultimate Tensile Strength (MPa) 2.00 up to 2.49 1720 - 1860 greater than 2.50 up to 2.99 1670 - 1810 greater than 3.00 up to 3.49 1670 - 1770 greater than 3.50 up to 3.99 1620 - 1720 greater than 4.00 up to 4.49 1570 - 1670 greater than 4.50 up to 4.99 1570 -
8、1670 Yield Strength, (0.2 % Offset), min 0.90 x UTS* Elongation (gauge length, 10 x d), min 7.0 % Reduction in Area, min 40 % * Ultimate Tensile Strength as determined on wire sample. NOTE: d denotes test wire diameter. 3.4 TORSION TEST A wire test piece of length 50X wire original diameter shall be
9、 unidirectionally twisted 6 revolutions then twisted in the reverse direction until fracture occurs. The rate of rotation shall not exceed 20 revolutions per minute. The primary fracture face shall exhibit a smooth shear surface formed at 90 to the axis of torsion. The presence of steps, shoulders o
10、r longitudinal cracks on the fracture face is not acceptable. Furthermore, no surface cracks on the twisted length of wire are permitted. 3.5 MICROSTRUCTURE The microstructure shall consist of a uniform fine tempered martensite. When a wire transverse microsection is viewed at 200 x magnification no
11、 complete decarburisation shall be permitted and partial decarburisation is only acceptable with the following constraints: Nominal Wire Diameter Depth of partial decarburisation 2.0 - 3.99 mm 0.024 mm, max 4.0 - 5.0 mm 0.032 mm, max No surface soft/hard spots due to local overheating from processin
12、g irregularities shall be permitted. No wire joins (weld) shall form part finished product, see also General Information 4.1. ENGINEERING MATERIAL SPECIFICATION WSD-M1A260-B1/B2 Page 3 of 5 Copyright 2002, Ford Global Technologies, Inc. 3.6 CLEANLINESS, wire and wire rod (ASTM E 45, Plate III Method
13、 A) The maximum inclusion content rating, as measured by above method, (except type D maximum 0.015 mm), shall be as follows: 3.6.1 Surface Area (from wire surface inward to a depth of 1/3rd the radius) Type A B C D Thin Heavy Thin Heavy Thin Heavy Thin Heavy =0.015 1.0 0.5 0.5 0 0.5 0.5 0.5 0 No in
14、dividual field shall be worse than: 1.5 1.0 0.5 0 1.0 1.0 0.5 0 The above procedure is statistically inadequate to fully guarantee the cleanliness of individual casts. Hence it is essential that the agreed steel making practice and cleanliness assessment is strictly monitored by means of the Control
15、 Plan. Assessments such as fatigue testing, dissolution evaluation or any other demonstrably informative technique shall be employed to increase cast acceptance confidence. Fatigue testing shall be undertaken by appropriate wire rotating bending methods, such as Nakamura, in which the wire test piec
16、e shall be shot peened, stress relieved, etc. to simulate valve spring processing. The intention of the additional fatigue testing is to establish an initial correlation to microscopic assessments. Microscopic evaluations shall be extended to include the thickness and the number distribution of non-
17、deformable inclusions (ASTM E 45 B and D combined) by such methods as max t or Swedish Standard SS 11 11 16, or modified versions of same. A certificate shall be supplied with each cast which will demonstrate the numerical distribution of the following width ranges (surface zone only): Up to 5.0 mic
18、rometres Greater than 5.0 up to 10.0 micrometres Greater than 10.0 up to 15.0 micrometres Greater than 15.0 micrometres This inclusion data will be collated with field performance and fatigue test results to form the basis for future Cleanliness requirements replacing the above ASTM call up. Periodi
19、c fatigue testing by the wire rod source shall be maintained to support validation and upgrading of any specified microscopic criteria. ENGINEERING MATERIAL SPECIFICATION WSD-M1A260-B1/B2 Page 4 of 5 Copyright 2002, Ford Global Technologies, Inc. 3.7 SURFACE CONDITIONS Button type (scab) imperfectio
20、ns are undesirable. Seams, scabs, small blunt nosed intrusions and other surface imperfections, for example, grooves and marks greater than 0.040 mm depth are not permitted. Cracks are unacceptable. 3.8 WIRE PROCESSING The wire processing will form part of control plan. 3.8.1 For WSD-M1A260-B1, the
21、wire shall be processed via a combination of drawing, surface and heat treatment processes but shall be supplied without surface preparation (such as shaving, turning, or belt grinding) at the wire rod or at any later stage of manufacture. 3.8.2 For WSD-M1A260-B2, the wire shall be given additional
22、processing prior to hardening in which the wire is dressed to give a uniform material surface removal of approximately 0.15 mm to further minimize surface seams and button defects. All surface requirements of 3.5 and 3.7 shall be met and surface imperfections, scoring, drag or laps, etc. shall not b
23、e introduced, the effect of which cannot be eliminated by current shot peening of the spring. 3.9 PART REQUIREMENTS 3.9.1 General After stress relieving and hot setting finished parts, the requirements of the wire shall remain unchanged from the preceding requirements. Stress relieving for a minimum
24、 of 30 minutes at temperatures, typically 355 - 425 C shall be performed promptly after coiling. These conditions or deviations to meet specific spring parameters will be part of the agreed spring control plan. 3.9.2 Fatigue Life, Engineering Requirements See affected engineering component specifica
25、tions for fatigue durability and other engineering requirements. ENGINEERING MATERIAL SPECIFICATION WSD-M1A260-B1/B2 Page 5 of 5 Copyright 2002, Ford Global Technologies, Inc. 4. GENERAL INFORMATION The information given below is provided for clarification and assistance in meeting the requirements
26、of this specification. 4.1 CHEMICAL COMPOSITION (weight per cent) Carbon 0.45 - 0.55 Manganese 0.60 - 0.90 Phosphorus 0.030 max Sulphur 0.025 max Silicon 0.15 - 0.30 Chromium 0.80 - 1.10 Vanadium 0.15 - 0.25 Oxygen * Aluminum * *The oxygen and aluminum contents shall be recorded as part of the contr
27、ol plan. Wire of the above composition may be approved at the control plan stage to assist in hot setting to which temperature it is less sensitive. Control plans are required to include these features outlined in 3.2. 4.2 MICROSTRUCTURE When microsections are examined at magnification of 500x it ma
28、y be possible to observe a fine isolated layer of complete decarburisation often associated with high temperature oxide. These features will be permitted providing they do not exceed 0.002 mm in depth. 4.3 HARDNESS The Vickers hardness value obtained on the spring may be used to compute the APPROXIMATE ultimate tensile strength of the wire using the formula: Vickers hardness value x 3.24 = U.T.S. of wire (MPa)
