1、 ENGINEERING MATERIAL SPECIFICATION Material Name Specification Number Date Action Revisions 2002 07 23 Revised Updated and renumbered 1998 09 23 Activated K. Thurgood (FAO) Printed copies are uncontrolled Page 1 of 6 Copyright 2002, Ford Global Technologies, Inc. STEEL, COIL AND LEAF SPRINGS WSS-M1
2、A271-B 1. SCOPE The materials described by this specification are alloy spring steels. 2. APPLICATION These materials were released originally for use in the manufacture of suspension springs. Coils and individual leaves may be specified on the drawings as either uniform thickness of section or as v
3、arying thickness of section. 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 SYSTEMS APPROVAL The materials described by this specification shall
4、 be subject to a source “Systems Approval,“ i.e. both the component supplier and steel supplier shall be approved in tandem. 3.3 GENERAL REQUIREMENTS Coil springs shall be made from ground bar, or bar from which the decarburized layer has been removed. 3.4 REQUIREMENTS FOR FINISHED SPRINGS 3.4.1 Gen
5、eral Restrictions 3.4.1.1 The component drawing may specify a restricted list of steel types together with other requirements such as hardness, surface condition, peening control, etc., which have been applied to springs that have successfully met the rig and durability requirements. 3.4.1.2 No stee
6、l other than those proved to be acceptable by prototype testing may be used in production unless prior approval from Ford Product Development is obtained. ENGINEERING MATERIAL SPECIFICATION WSS-M1A271-B Page 2 of 6 Copyright 2002, Ford Global Technologies, Inc. 3.4.1.3 The component engineer must be
7、 supplied with the composition and properties of each batch of prototype springs. 3.4.2 Chemical Composition This shall form part of the Control Plan. General information is shown in para 4.3. 3.4.3 Non-metallic Impurities Inclusion Type: A B C D T H T H T H T H Silicon Steel 3.5 2 3 1.5 2.5 1.5 2 1
8、.5 Non-silicon 3.5 2 3 1.5 1.5 1 2 1.5 Steel T = Thin Series H = Heavy Series There is no requirement on sulfide inclusions (Type A) when the sulfur content is 0.035 % or less. The above requirement is either on billets to ASTM E 45 Method A or on finished springs to FLTM EU-BA 051-02. Alternatively
9、 the Stahl-Eisen Prufblatt 1570-71 method may be used: K4 value 20 maximum (oxides only). If the sulfur content is greater than 0.035 % the limits in the above table apply. 3.4.4 Grain Size The steel shall have an austenitic grain size of 5 or finer. 3.4.5 Decarburization (FLTM EU-BA 053-01) The fol
10、lowing limits of decarburization shall apply to the finished spring. Coil Springs Up to 13 mm diameter Complete decarburization Nil Total decarburization - 0.15 mm maximum ENGINEERING MATERIAL SPECIFICATION WSS-M1A271-B Page 3 of 6 Copyright 2002, Ford Global Technologies, Inc. Above 13 mm diameter
11、Complete decarburization - Nil Total decarburization - 0.20 mm maximum Leaf Springs (Silicon Steels) Up to and including Complete decarburization - 0.05 7 mm thick maximum Total decarburization - 0.25 mm maximum Over 7 mm and up to Complete decarburization - 0.05 and including 14 mm maximum thick To
12、tal decarburization - 0.35 mm maximum Above 14 mm thick Complete decarburization - 0.05 mm maximum Total decarburization 2.5 % of the spring thickness at sectioned position. Leaf Springs (Nonsilicon Steels) Up to 12.5 mm thick Complete decarburization - 0.05 mm maximum Total decarburization - 0.25 m
13、m maximum Above 12.5 mm thick Complete decarburization - 0.05 mm maximum Total decarburization 2 % of the spring thickness at sectioned position. 3.4.6 Hardenability The steel used shall be chosen and controlled to have adequate hardenability for the section size of the spring. Its hardenability sha
14、ll be ensured by progressing a pilot sample of the stock through the production heat treatment and conforming to para 3.4.6.1 and 3.4.6.2. 3.4.6.1 Hardness “As Quenched“ After removing any decarburized layer, the surface hardness must be: HRC 56 minimum or HB* 555 minimum or HV/30 610 minimum ENGINE
15、ERING MATERIAL SPECIFICATION WSS-M1A271-B Page 4 of 6 Copyright 2002, Ford Global Technologies, Inc. *Using Tungsten Carbide Ball or Cemented Alloy Carbide Ball. The surface must be free from cracks when examined immediately after quenching. 3.4.6.2 Hardness after Tempering After tempering to the ha
16、rdness range specified on the drawing, the hardness differential between surface (after removal of decarburization) and the center section shall not be greater than an average of 35 points Brinell Hardness for any individual sample. 3.4.7 Control of Hardenability & Heat Treatment 3.4.7.1 The hardena
17、bility and heat treatment of the steel in production shall be controlled by the supplier by any suitable means such that any sample taken from production will meet the requirements of para 3.4.6.1 and 3.4.6.2. The minimum tempering temperature is 370 C. 3.4.7.2 All parts which are to be heat treated
18、 to a surface hardness of HV390 or greater must be cleaned prior to heat treatment by alkaline or inhibited acid process to remove all phosphate and associated lubricant residues from the surface. 3.4.7.3 Carburization of through hardened parts is not permitted unless specified on the Engineering Dr
19、awing. The surface hardness of all through hardened parts must not exceed the sub-surface hardness by more than 30 Vickers points, determined by the HV 0.3 method. The sub-surface hardness position is defined as a point 0.5 mm below the surface. 3.4.8 Microstructure The microstructure shall consist
20、of tempered martensite and similar transformation products. Pearlite is not allowed. Free ferrite may only be present in the decarburized zone (see para 3.4.5). 3.4.9 Surface Finish The spring shall be free from cracks. Surface inspection by visual or magnetic defect examination techniques shall be
21、carried out in the unpainted state if stated on the drawing. The maximum depth of surface imperfections shall be 0.15 mm. ENGINEERING MATERIAL SPECIFICATION WSS-M1A271-B Page 5 of 6 Copyright 2002, Ford Global Technologies, Inc. 4. GENERAL INFORMATION The information given below is provided for clar
22、ification and assistance in meeting the requirements of this specification. Shot Peening (See para. 4.2) ) Surface Coating ) To be specified on the Scragging ) Engineering Drawing or in the Fatigue Requirement ) Engineering Specification. Hardness ) Crack Detection (if required) ) 4.1 Various user,
23、national and international standard grades that fall within the stated analytical ranges are listed in para 4.3. 4.2 Stress peening generates a higher compressive stress, i.e., residual stress (typically 500 to 800 Mn/m2) than does free peening. Stress peening with close control on edge peening is c
24、onsidered to offer a valuable contribution to improved fatigue life. A method for determining the level of residual stress is via an X-ray diffraction technique. 4.3 Chemical Composition Previously used suffices are shown below for reference purposes only: A1 A2 A3 250A53 RVSS 100/1 SiMn1 55SiCr 7 6
25、0SiCr 7 C 0.50 - 0.58 0.52 - 0.60 0.55 - 0.65 Si 1.70 - 2.10 1.50 - 1.80 1.50 - 1.80 Mn 0.70 - 1.00 0.70 - 1.00 0.70 - 1.00 Cr 0.30 maximum 0.20 - 0.40 0.20 - 0.40 P 0.040 maximum 0.050 maximum 0.045 maximum S 0.040 maximum 0.050 maximum 0.045 maximum A4 A5 A6 250A58,250A61 527A60,SAE 5160 SAE 9260,
26、 ISO SAE 5155, 55Cr3 ISO Type 9 Type 6 or 7 ISO Type 8 RVSS 100/1 CCr2 RVSS 100/1 Si Mn2 RVSS 100/1 CCr1 and CCr3 C 0.55 - 0.65 0.51 - 0.59 0.55 - 0.65 Si 1.70 - 2.20 0.15 - 0.40 0.10 - 0.40 Mn 0.70 - 1.00 0.70 - 1.00 0.70 - 1.05 Cr 0.40 maximum 0.60 - 0.90 0.60 - 1.00 P 0.040 maximum 0.040 maximum
27、0.040 maximum S 0.040 maximum 0.040 maximum 0.040 maximum ENGINEERING MATERIAL SPECIFICATION WSS-M1A271-B Page 6 of 6 Copyright 2002, Ford Global Technologies, Inc. A7 A8 A9 SAE 4161 SAE 6150, 50CrV4 ISO Type 12 ISO Type 13, RVSS 100/1 SAE 51B 60 735A50 CrMo1 & CrMo2 ISO Type 10 C 0.46 - 0.57 0.55 -
28、 0.64 0.56 - 0.64 Si 0.10 - 0.40 0.15 - 0.40 0.15 - 0.40 Mn 0.60 - 1.15 0.70 - 1.00 0.70 - 1.00 Cr 0.80 - 1.20 0.70 - 0.90 0.60 - 0.90 P 0.040 maximum 0.035 maximum 0.035 maximum S 0.040 maximum 0.040 maximum 0.040 maximum B - - 0.0005 minimum Mo - 0.15 - 0.35 - V 0.10 - 0.30 - - A10 A11 A12 f 140 C
29、, f 144 C 51CrMoV4 ISO Type 7 52MnCrB3 ISO Type 14 C 0.55 - 0.65 0.48 - 0.55 0.48 - 0.57 Si 1.45 - 2.00 0.15 - 0.40 0.15 - 0.40 Mn 0.65 - 0.95 0.75 - 1.00 0.70 - 1.10 Cr 0.20 - 0.50 0.40 - 0.60 0.90 - 1.20 P 0.040 maximum 0.035 maximum 0.035 maximum S 0.040 maximum 0.035 maximum 0.035 maximum B - 0.
30、0005 - 0.005 - Mo - - 0.15 - 0.25 V - - 0.07 - 0.12 A13 A14 54SiCr6 45SiCrV6 C 0.51 - 0.59 0.40 - 0.50 Si 1.20 - 1.60 1.30 - 1.60 Mn 0.50 - 0.80 0.50 - 0.70 Cr 0.50 - 0.80 1.30 - 1.60 P 0.030 maximum 0.035 maximum S 0.030 maximum 0.035 maximum Mo - - V - 0.07 - 0.12 Types A1, A2, A3, A4, A10, A13 and A14 are classified as silicon steels.
