1、 WORLDWIDE ENGINEERING STANDARDS Material Specification GMW16807 Spring Materials Oil Tempered Valve Spring Quality Copyright 2012 General Motors Company All Rights Reserved July 2012 Originating Department: North American Engineering Standards Page 1 of 7 1 Scope This specification covers three gra
2、des of special quality round and ovate steel wire intended for the manufacture of valve springs requiring resistance to set when used at moderately elevated temperatures and high stress levels. This wire shall be in the tempered condition as specified by the purchaser. Type A wire has the lowest ten
3、sile strength. Type B wire is an intermediate tensile strength grade and Type C wire is a high tensile strength grade. 1.1 Material Description. This steel shall be made by any GM approved steel making practice, such as the electric arc furnace or the basic oxygen process. This steel shall be contin
4、uously cast. The subsequent refining processes must include the use of secondary ladle refining and the use of silicon for deoxidation purposes. The resulting inclusions shall be predominantly of a deformable nature. This material is considered super clean steel. 1.2 Symbols. Not applicable. 1.3 Typ
5、ical Applications. Engine valve springs. 1.4 Remarks. Not applicable. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASTM A751 ISO 6892 2.2 GM Standards/Specifications. GMW3059 2.3 Additional References. TMC003
6、Material Safety Data Sheet guidance documents (available at ). 3 Requirements 3.1 Requirements on Delivery. 3.1.1 Chemical Requirements. The steel furnished to this specification shall conform to the composition listed in Table 1. Each heat of steel shall be analyzed by the steel manufacturer to det
7、ermine the percentage of elements using ASTM A751. Analysis may also be done by the purchaser on the finished wire. Conformance to the chemical composition is required. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networki
8、ng permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16807 Copyright 2012 General Motors Company All Rights Reserved July 2012 Page 2 of 7 Table 1: Chemical Requirements Type A Type B Type C CrSi CrSiV CrSiNiV CrSiNiV CrSiMoV Element (Weight %) (Weight %) (Weight %) (Weigh
9、t %) (Weight %) Carbon 0.50 to 0.60 0.55 to 0.70 0.57 to 0.62 0.50 to 0.70 0.50 to 0.70 Silicon 1.20 to 1.60 1.20 to 1.60 1.30 to 1.60 1.80 to 2.20 1.80 to 2.20 Manganese 0.50 to 0.80 0.50 to 0.80 0.50 to 0.80 0.70 to 1.00 0.30 to 0.60 Phosphorous 0.025 maximum 0.020 maximum 0.020 maximum 0.020 maxi
10、mum 0.020 maximum Sulfur 0.025 maximum 0.020 maximum 0.020 maximum 0.020 maximum 0.020 maximum Copper - 0.15 maximum 0.15 maximum 0.15 maximum - Nickel - - 0.20 to 0.50 0.20 to 0.40 - Chromium 0.50 to 0.80 0.50 to 0.70 0.80 to 1.0 0.80 1.05 0.80 to 1.00 Vanadium - 0.08 to 0.18 0.05 to 0.10 0.05 to 0
11、.15 0.05 to 0.15 Molybdenum - - - - 0.05 0.15 3.1.2 Mechanical Requirements. 3.1.2.1 Unless otherwise specified by the purchaser, wire shall be shaved, drawn, austenitized, quenched and tempered. The tensile strength of the wire shall conform to the limits shown in Table 2 for the various sizes show
12、n (for non-round wires, use the equivalent round wire diameter). The initial cross sectional area for round and non-round wires can be calculated per the procedure in ISO 6892, Annex C; or by measuring a samples minimum and maximum diameters (width and thickness) and multiplying by a shape factor. 3
13、.1.2.1.1 The shape factor can be either derived from the nominal shape of the cross section, or it can be determined by dividing the area calculated per ISO 6892, Annex C by the measured width times the thickness. The reduction of area for sizes listed in Table 2 shall be 40% minimum. Final cross se
14、ctional area for non-round shapes can be calculated by multiplying the shape factor by the measured width times the thickness in the necked cross section. 3.1.2.2 One (1) tensile test specimen shall be taken from each end of a coil. Tensile strength within one coil shall not vary by more than 70 MPa
15、 for Types A and B and not more than 50 MPa for Type C. Each coil shall be tested. The tensile test shall follow the test procedure in ISO 6892. 3.1.2.3 Wrap Test. For Type A material, round wire or ovate wire cross sections through 4.0 mm diameter shall wind (as a close wound helix) on itself as an
16、 arbor (or an arbor of equivalent round wire diameter) for at least two turns without breaking or checking the surface. Type A wire over 4.0 mm through 8.0 mm inclusive and all Type B and Type C wire cross sections, shall wind on an arbor twice its diameter for at least two turns without breaking or
17、 checking the surface. The wrap test is not applicable for ovate or round wire diameters greater than 8.0 mm. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGI
18、NEERING STANDARDS GMW16807 Copyright 2012 General Motors Company All Rights Reserved July 2012 Page 3 of 7 Table 2: Tensile Strength of Wire Tensile Strength Mpa Wire Diameter, mm Type A Type B Type C 2.5 to 3.2 1920 to 2080 2060 to 2160 2110 to 2210 3.21 to 4.00 1900 to 2040 2010 to 2110 2060 to 21
19、60 4.01 to 5.00 1820 to 1980 1960 to 2060 2010 to 2110 5.01 to 6.00 1780 to 1920 1910 to 2010 1960 to 2060 6.01 to 7.00 1720 to 1900 7.01 to 8.00 1700 to 1860 3.1.3 Metallurgical Requirements. 3.1.3.1 Shaving Requirements. The original rod wire surface shall be shaved to remove 150 m of material per
20、 side. 3.1.3.2 Surface Conditions. The final wire surface shall be smooth and free from rust, scale, die marks, deep scratches, seams, cracks, and other surface defects 40 m in size and larger, which are detectable using eddy current testing via stationary and rotary probe testers. All wire sections
21、 with an indicated defect shall be painted by the wire processor, so that these sections can be discarded during the spring manufacturing process. The number of painted defects per coil shall be tracked and submitted to the valve spring supplier to ensure that all defects are accounted for during th
22、e spring coiling process. During the coiling process the painted length plus the length equivalent to one spring before and after the paint defect shall be discarded. 3.1.3.2.1 Acid Etch. An optional acid etch test using 50% Hydrochloric Acid (HCl) in water at 80 C may be used to remove the surface
23、oxide scale for closer visual examination of the wire surface for defects. 3.1.3.3 Microstructure. A longitudinal section shall show a fine homogeneous tempered martensitic structure. Decarburization shall be determined by etching a polished transverse cross section of the wire in 5% nital and exami
24、ning the entire periphery at 100X magnification, measuring the worst area present, not associated with a seam or other defect. Examination shall show no completely decarburized areas. Partial decarburization shall not exceed a depth of 1.5% of the wire diameter or 0.025 mm whichever is smaller on wi
25、re 5.00 mm and smaller, or 0.038 mm on wire larger than 5.00 mm in diameter. One (1) test specimen shall be taken from at least one coil per heat. Test specimens may be taken from either end of the coil. 3.1.3.4 Inclusion Content. For inclusion content evaluation, longitudinal sections shall be grou
26、nd to the centerline and properly mounted and polished. Two methods are acceptable for measuring inclusion thickness, the Max-T Method and the Ovako Method. 3.1.3.4.1 Max-T Method: In the Max-T Method, a section of wire 20 mm in length is sectioned, ground to the centerline and properly mounted and
27、polished. For a wire or a wire rod, the area of evaluation shall be a zone from the surface to the outer one-half (1/2) radius of the wire. The sample is evaluated at 100X magnification. The thickness of the largest inclusion, measured transverse to the wire axis, in each 20 mm zone shall be recorde
28、d. Each zone will yield one data point. A minimum of 10 samples per lot are to be evaluated for a total surface area of 800 mm2. The maximum inclusion thickness found in each 20 mm zone shall be recorded and graded into a minimum of three size ranges per Table 3. 3.1.3.4.2 Ovako Method: In the Ovako
29、 Method, a section of wire is ground to the centerline and properly mounted and polished. The outer 1 mm of material on both sides of the wire sample are evaluated at 100X magnification. The thickness of all inclusions 5 microns, measured transverse to the wire axis, shall be recorded in Table 4. A
30、minimum surface area of 125 mm2 per coil shall be evaluated. A minimum surface area of 1000 mm2 shall be evaluated per lot. A summary of the Max-T Method and the Ovako Method is given in Appendix A. 3.1.3.4.3 There shall be no inclusions of thickness 15 m. Copyright General Motors Company Provided b
31、y IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16807 Copyright 2012 General Motors Company All Rights Reserved July 2012 Page 4 of 7 3.1.3.4.4 The information reported should incl
32、ude the test method, the number of inclusions per coil of thickness 5 m, the largest inclusion size per coil or the distribution of sizes present. If the inclusion distribution from a single coil does not meet the requirements, then that coil shall be rejected. If two coils tested from the same lot
33、fail to meet the requirements, the entire lot will be rejected. Any other lots from the same cast heat are rejectable. Table 3: Maximum Allowable Inclusion Thickness Using the Max-T Method % of fields 10% Maximum 0 Inclusion size 10 to 15 m 15 m Note: Minimum observed area per coil is 125 mm2. Inclu
34、sions less than 5 m in thickness are not counted. Table 4: Maximum Allowable Number of Inclusions Using the Ovako Method Number of Inclusions/1000 mm2 50 7 0 Inclusion size 5 to 10 m 10 to 15 m 15 m Note: Minimum observed area per coil is 125 mm2. Inclusions less than 5 m in thickness not counted. 3
35、.2 Processing Requirements. 3.2.1 The wire shall be uniform in quality and in temper and shall not be wavy or crooked. It shall be homogeneous and any surface markings that are identifiable using rotary and/or stationary eddy current testers shall be clearly marked with paint so that these sections
36、can be discarded during the further processing of the wire or spring. 3.2.2 The coil mass, dimensions, and the type of protective coating as well as packaging should be agreed upon between the wire manufacturer and the spring manufacturer. Coils shall be protected from surface damage that might occu
37、r during storage or from handling. 3.3 Dimensional Variation. 3.3.1 The permissible variation in the diameter of round and ovate wires is specified in Table 5 and Table 6 respectively. The wire shall not be out of round by more than one-half (1/2) the total diameter tolerance shown in Table 5. Table
38、 5: Permissible Variation in Wire Diameter Diameter, mm Tolerance, mm 0.5 to 2.0 included 0.02 Over 2.0 to 4.0 included 0.03 Over 4.0 to 9.5 included 0.04 Table 6: Permissible Variation for Ovate Wire Diameter, mm Tolerance, mm 1.90 to 3.75 0.025 Over 3.75 to 6.0 0.030 Over 6.0 to 8.0 0.040 4 Manufa
39、cturing Process Not applicable. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16807 Copyright 2012 General Motors Company All Rights Re
40、served July 2012 Page 5 of 7 5 Rules and Regulations 5.1 Legal Regulations. All materials must satisfy applicable laws, rules, regulations and recommendations valid in the country of usage. 5.2 Language. In the event of conflict between the English and domestic language, the English language shall t
41、ake precedence. 5.3 Inspection and Rejection. Samples of components or materials released to a GM material specification shall be tested for conformity with the requirements of this material specification and approved by the responsible Engineering department prior to commencement of delivery of bul
42、k supplies. A new approval must be received for any changes, e.g., properties, manufacturing process, location of manufacture, etc. If not otherwise agreed, all testing and documentation normally required for initial release must be completed. It is the responsibility of the supplier to inform the c
43、ustomer in a timely manner, without solicitation, and to include documentation of all modifications of materials and/or processes and to apply for a new release. If not otherwise agreed, all release tests shall be repeated and documented by the supplier prior to commencement of delivery of non-confo
44、rming bulk supplies. In individual cases, a shorter test can be agreed to between the responsible Engineering department and the supplier. 5.4 Initial Source Approval. No shipments shall be made by any supplier until representative initial production samples have been approved by the appropriate Mat
45、erials Engineering department(s) as meeting the requirements of this specification. 5.5 Material Safety Data Sheets/Safety Data Sheets (MSDS/SDS). For new product submissions, or when a change in chemical composition of an existing product has occurred, a complete copy of the Material Safety Data Sh
46、eet/Safety Data Sheet must be submitted in compliance with the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) requirements or other country-specific MSDS/SDS requirements. In addition, product MSDS/SDS submissions must be in compliance with specific country General Moto
47、rs TMC003 Material Safety Data Sheet/Safety Data Sheet guidance documents where available. 5.6 All materials supplied to this standard must comply with the requirements of GMW3059, Restricted and Reportable Substances for Parts. 6 Approved Sources Not applicable. 7 Notes 7.1 Glossary. Max-T: Maximum
48、 Thickness inclusion measuring method. 7.2 Acronyms, Abbreviations, and Symbols. CrSi Chrome Silicon Alloy CrSiMoV Chrome Silicon Molybdenum Vanadium Alloy CrSiNiV Chrome Silicon Nickel Vanadium Alloy CrSiV Chrome Silicon Vanadium Alloy GHS Globally Harmonized System of Classification and Labeling o
49、f Chemicals HCI Hydrochloric Acid Max Maximum MSDS Material Safety Data Sheet SDS Safety Data Sheet Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16807 Copyright 2012 General Motors Company All Rights Rese
