1、 WORLDWIDE ENGINEERING STANDARDS Material Specification GMW16820 Mechanical and Quality Requirements for Die Drawn Suspension U-Bolts Copyright 2012 General Motors Company All Rights Reserved November 2012 Originating Department: North American Engineering Standards Page 1 of 5 1 Scope 1.1 Material
2、Description. This standard covers the mechanical, material and quality requirements for two (2) grades of die drawn carbon and alloy steel suspension type U-Bolts in nominal thread diameters of M10 thru M24. The term U-Bolt as referred to herein applies to a cold drawn cylindrical rod, threaded on b
3、oth ends and formed as round bend or square bend U-Bolt. Property classes, Grade A and B, are designated as follows: GMW16820: Grade A. GMW16820: Grade A Stress Relieved. GMW16820: Grade B. GMW16820: Grade B Stress Relieved. 1.2 Symbols. Not applicable. 1.3 Typical Applications. Leaf Spring U-Bolts.
4、 1.4 Remarks. See Appendix A, Table A1 for regional cross reference chart. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASTM E18 SAE J403 SAE/USCAR-5 ISO 6157 SAE J417 SAE/USCAR-7 2.2 GM Standards/Specificatio
5、ns. GMW3059 GMW16551 2.3 Additional References. TMC003 Material Safety Data Sheet guidance documents (available at ). 3 Requirements 3.1 Requirements on Test Specimens. Not applicable. 3.2 General Requirements. 3.2.1 The tensile strength will take precedence to hardness. When the specified hardness
6、and tensile strength cannot be met simultaneously, a revised hardness range shall be established by agreement between the supplier and purchaser. 3.2.2 The U Bolt must be free of burrs which may be detrimental to satisfactory assembly, safe handling or function as defined by the purchaser. 3.3 Mater
7、ial and Process. 3.3.1 U Bolts shall be made of medium carbon or medium carbon alloy steel as shown in Table 1. 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 EN
8、GINEERING STANDARDS GMW16820 Copyright 2012 General Motors Company All Rights Reserved November 2012 Page 2 of 5 Table 1: Chemical Composition Requirements Property Class Material Description Steel Grade per SAE J403 Grade A and Grade A Stress Relieved Medium Carbon or Medium Carbon Alloy Steel 1050
9、, 1541, 1547,1548, 1552 Grade B and Grade B Stress Relieved Medium Carbon Alloy Steel 1541, 1547,1548, 1552 3.3.2 Threading Process. Threads shall be roll formed unless otherwise specified on the product drawing. Thread quality must meet GMW16551. 3.3.3 Cleaning. Concentrated acids, such as, hydroch
10、loric acid, shall not be used during the manufacturing or plating/coating of the U-Bolt. 3.3.4 Stress Relief. Grade A Stress Relieved and Grade B Stress Relieved shall be identified on the drawing as shown in 1.1. Finished U-Bolts shall be stress relieved at a temperature of not less than 288 C for
11、a minimum of 30 minutes. 3.3.5 Hydrogen Embrittlement. All U-Bolts processed through a hydrogen generating process, such as acid cleaning or electroplating, shall be hydrogen embrittlement relieved per SAE/USCAR-5. Verification of embrittlement relief shall be performed per SAE/USCAR-7. 3.4 Mechanic
12、al Properties. 3.4.1 The U-Bolts shall meet the Mechanical Properties shown in Table 2. The listed tensile strength represents the minimum value for the threaded portion of one U-Bolt leg. Table 2: Mechanical Properties Property Class Tensile Strength, (Rm) Minimum Yield Strength, Minimum Hardness,
13、HRc, for Reference Hardness, Vickers HV10 for Reference Grade A and Grade A Stress Relieved 900 MPa 720 MPa 25 to 32 280 Grade B and Grade B Stress Relieved 1040 MPa 832 MPa 30 to 36 320 3.4.2 Mechanical properties shall be determined by testing the U-Bolt over a test saddle. The Saddle Tensile Test
14、 is described in A1.1. Hardness Testing is described in A1.2. The minimum tensile load, (LT) in kilonewton (kN) based on the Tensile Strength, (Rm) in Megapascals (MPa) shown in Table 2 for a saddle tensile test of a complete U-Bolt is calculated as follows: LT minimum = 0.0016991 (As x Rm) As = 0.7
15、854 (D - 0.9382P) 2 Where As =Thread Stress Area in mm2, D = Nominal Thread Diameter in millimeters (mm) and P=Thread Pitch in millimeters (mm). Example: M14 U-Bolt with Thread Pitch=2.00 mm As =0.7854(14.00-0.9382(2.00)2 = 115.44 mm2 LT minimum = 0.0016991(115.44 900) = 176.51 kN Copyright General
16、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 GMW16820 Copyright 2012 General Motors Company All Rights Reserved November 2012 Page 3 of 5 3.4.3 Surface har
17、dness shall not exceed base metal hardness by more than two (2) points, Hardness Rockwell (HRc) equivalent. 3.5 Surface Discontinuities. U-Bolts shall not have surface discontinuities exceeding the limits specified in ISO 6157. Surface discontinuities for sizes and lengths not covered in the scope o
18、f ISO 6157 shall be defined by the responsible GM Fastener Engineer. Discontinuities at the root of the thread due to use of serrated thread forming dies are permissible if the serrations do not affect the mechanical properties of the thread. 4 Manufacturing Process 5 Rules and Regulations 5.1 Legal
19、 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 take precedence. 5.3 Inspection and Rejection. Samples of compo
20、nents 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 bulk supplies. A new approval must be received for any changes, e
21、.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 customer in a timely manner, without solicitation, and to inclu
22、de 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-conforming bulk supplies. In individual cases, a shorter test can b
23、e agreed to between the responsible Engineering department and the supplier. 5.4 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 Sheet/Saf
24、ety 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 Motors TMC0
25、03 Material Safety Data Sheet/Safety Data Sheet guidance documents where available. 5.5 All materials supplied to this standard must comply with the requirements of GMW3059, Restricted and Reportable Substances for Parts. 6 Approved Sources Materials supplied to this specification must be approved b
26、y General Motors. A list of approved materials can be found in MATSPC. This GM Material File is provided to third parties to reduce redundant testing of materials. If approved material already listed is used, the part supplier can use GM Material File reference for Production Part Approval Process (
27、PPAP) material approval. If the decision is made to use a not yet approved material, contact the Chassis Fastening Global Subsystem Leadership Team for detail on the approval process. The material approval process must be completed prior to PPAP start date of the part supplied to General Motors. 7 N
28、otes 7.1 Glossary. MATSPC: Global repository of GM Approved Materials for corresponding GM Engineering Standards. 7.2 Acronyms, Abbreviations, and Symbols. ASTM ASTM International HRc Hardness Rockwell GHS Globally Harmonized System of Classification and Labeling of Chemicals Copyright General Motor
29、s Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16820 Copyright 2012 General Motors Company All Rights Reserved November 2012 Page 4 of 5 HV Hardness Vickers LT
30、 Tensile Load MPa Megapascal MSDS Material Safety Data Sheet kN Kilonewton PPAP Production Part Approval Process Rm Tensile Strength SAE SAE International SDS Safety Data Sheet 8 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: Die Drawn U-Bolt per GMW1
31、6820 Grade X Where X = Grade as shown in 1.1 9 Release and Revisions This standard was originated in June 2012. It was first approved by the Chassis Fastening Global Subsystem Leadership Team in November 2012. It was first published in November 2012. Issue Publication Date Description (Organization)
32、 1 NOV 2012 Initial publication. 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 GMW16820 Copyright 2012 General Motors Company All Rights R
33、eserved November 2012 Page 5 of 5 Appendix A Table A1: Cross Reference to GM511M GM511M Grade Corresponding GMW16820 Grade Grade A Grade A Grade A Stress Relieved Grade A Stress Relieved Grade B Grade B Grade B Stress Relieved Grade B Stress Relieved A1 Test Methods A1.1 Saddle Tensile Test. The U-B
34、olt shall be fitted with a saddle block which fits snugly between the legs of the U-Bolt and has sufficient mass to support the loads required to test the particular U-Bolt. See Appendix A, Figure A1 A1.2 Product (Base Metal) Hardness. The hardness shall be determined at mid radius of a transverse s
35、ection through the threaded portion taken at a distance of one (1) diameter from the end of the product. The preparation of test specimens and the performance of hardness tests shall be in conformity with the requirements of SAE J417 or ASTM E18. A1.2.1 Surface Hardness. Surface hardness of the unth
36、readed shank shall be conducted according to ASTM E18. Surface hardness may be performed as an alternate to core hardness. Figure A1: Saddle Tensile Test Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
