1、 ENGINEERING MATERIAL SPECIFICATION Material Name Specification Number Date Action Revisions 2002 09 25 Revised Updated & Renumbered 1991 12 12 C10181730 Released N. Riley EAO, C. Webster NAAO Printed copies are uncontrolled Page 1 of 4 Copyright 2002, Ford Global Technologies, Inc. STEEL WIRE - VAL
2、VE SPRING, CHROMIUM WSD-M1A319-A1 SILICON ALLOY, DRESSED SURFACE 1. SCOPE The material defined by this specification is an oil hardened and tempered chromium-silicon alloy high quality steel spring wire. In general, steels shall be specially melted and processed to give a clean steel of uniform core
3、 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. 3. REQUIREMENTS 3.1 STANDARD REQUIREMENTS FOR PRODUCTION MATERIALS Mater
4、ial suppliers and part producers must conform to the Companys Standard Requirements For Production Materials (WSS-M99P1111-A). 3.2 CHEMICAL COMPOSITION (weight per cent.) Carbon 0.50 - 0.60 Manganese 0.50 - 0.80 Phosphorus 0.030 max Sulphur 0.025 max Silicon 1.20 - 1.65 Chromium 0.50 - 0.80 Oxygen *
5、 Aluminum * * The oxygen and aluminum contents shall be recorded as part of the control plan. Specific composition limits, melting and casting practice, rod, wire and heat treatment processing route to meet performance and manufacturing requirements will form part of an agreed control plan for each
6、spring component. ENGINEERING MATERIAL SPECIFICATION WSD-M1A319-A1 Page 2 of 4 Copyright 2002, Ford Global Technologies, Inc. 3.3 MECHANICAL PROPERTIES (ASTM E8M) (as delivered for spring manufacture) Wire Diameter (mm) Ultimate Tensile Strength (MPa) 2.00 up to 2.50 1960 - 2060 greater than 2.50 up
7、 to 3.00 1910 - 2010 greater than 3.00 up to 3.50 1910 - 2010 greater than 3.50 up to 4.00 1860 - 1960 greater than 4.00 up to 4.50 1860 - 1960 greater than 4.50 up to 5.00 1810 - 1910 Yield Strength (0.2% Offset), min 0.92 x UTS* Elongation (gauge length, 10 x d), min 7.0 % Reduction in Area, min 4
8、0 % * Ultimate Tensile Strength as determined on wire sample. NOTE: d denotes test wire diameter. 3.4 TORSION TEST A wire test piece of length 250 mm shall be unidirectionally twisted without failure, under the following conditions: Up to and including 2.50 mm wire dia. 5 revolutions above 2.50 mm w
9、ire dia. 3 revolutions The rate of rotation shall not exceed 20 revolutions per minute. 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 mag
10、nification, no 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
11、 from processing irregularities shall be permitted. No wire joins (weld) shall form part finished product, see also General Information 4.1. ENGINEERING MATERIAL SPECIFICATION WSD-M1A319-A1 Page 3 of 4 Copyright 2002, Ford Global Technologies, Inc. 3.6 CLEANLINESS (Wire and Wire rod), (ASTM E 45, Pl
12、ate III Method 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
13、.5 0.5 0 No individual 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 valve springs. Hence it is essential that the agreed steel making practice and cleanliness assessment is strictly monitored b
14、y means of the Control Plan. Periodic fatigue testing by the wire rod source shall be maintained to support validation and upgrading of any specified microscopic criteria. Assessments such as dissolution evaluation, extended microscopic evaluations to include distribution and maximum thickness of no
15、n-deformable inclusions (ASTM E 45 types B and D combined), or any other established technique shall be performed on a continuous basis and correlated with fatigue test results and field performance. This shall be part of the control plan to continuously reduce variation in the final product. 3.7 SU
16、RFACE CONDITIONS Button type (scab) imperfections 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
17、 of control plan. The wire shall be given additional processing prior to hardening in which the wire is dressed to give a uniform material surface removal of approximately 0.15mm to further minimize surface seams and button defects. All surface requirements of 3.5 and 3.7 shall be met and surface im
18、perfections, scoring, drag or laps etc. shall not be introduced, the effect of which cannot be eliminated by current shot peening of the spring. ENGINEERING MATERIAL SPECIFICATION WSD-M1A319-A1 Page 4 of 4 Copyright 2002, Ford Global Technologies, Inc. 3.9 PART REQUIREMENTS 3.9.1 General After stres
19、s relieving and hot setting finished parts, the requirements of the wire shall remain unchanged from the preceeding requirements. Stress relieving for a minimum of 30 minutes at temperatures, typically 400 - 425 C shall be performed promptly after coiling. These conditions or deviations to meet spec
20、ific spring parameters will be part of the agreed spring control plan. 3.9.2 Fatigue life, engineering requirements See affected engineering component specifications for fatigue durability and other engineering requirements. 4. GENERAL INFORMATION The information given below is provided for clarific
21、ation and assistance in meeting the requirements of this specification. 4.1 MICROSTRUCTURE When microsections are examined at magnification of 500x it may 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. 4.2 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)
