GM9769P-Sheet steel Qualification-1.doc

GM ENGINEERING STANDARDSGM9769PInstructions: Instructions are for user assistance only and are not part of the document structure. Instructions can be turned on and off using the “show/hide” () button on the MS Word Standard toolbar. Instructions should not be included on the printed copy. If instructions appear, select File - Print. When the Print dialogue box appears select the Options button and deselect “Hidden Text.”Instructions: To work in a single column format, select View - Normal. Select View - Page Layout to return to double column. The printed form will always remain double column.Instructions: Titles will be as concise as possible but complete enough to identify the material covered by the specification.1 ScopeThis procedure defines the process and requirements a steel producer or processor (electrogalvanized or hot dip galvanized coating supplier) must meet to qualify their steel products and processing lines. Technical approval is required to supply to General Motors these materials defined by GM Engineering Materials and Process Standards.1.1 Material Requirements. The intent of this procedure is to obtain information to ascertain a steel producers ability to produce and supply steel that meets the requirements of GM. Emphasis is placed on the steel producers ability to supply a uniform and consistent product. Some material characteristic and attribute data are requested for qualification purposes even though they are not requirements of the specific GM Standard.1.2 Manufacturing Requirements. An additional intent of this procedure is, through a plant try out, to ascertain the ability of this sheet steel to be formed, welded, bonded, cleaned, and painted in GM manufacturing and assembly operations. Note: Nothing in the specifications, however, supercedes applicable laws and regulations unless a specific exemption has been obtained.Note: In the event of a conflict between the English and domestic language, the English language shall take precedence.1.3 Definitions1.3.1 Processing Line Definitions.1.3.1.1 A new base metal or coating is defined as a new or significantly changed product from an existing process or a new process. Significantly changed includes, but is not limited to, a new steel chemistry, new coating chemistry, change in annealing process, change in rolling process, etc.1.3.1.2 An approved base metal or coating is one that has previously been granted a technical approval by the SMST.1.3.1.3 A new combination is defined as a combination of an approved base metal and an approved coating which have not been previously used together to produce an approved product.2 ReferencesNote: Only the latest approved standards are applicable unless otherwise specified.2.1 Normative.ASTM A90ASTM A370ASTM A653 ASTM A754ASTM A917 ASTM B571 ASTM E45 ASTM E112 ASTM E517 ASTM E646 SAE J911 QS9000 ANSI/AWS/SAE/ D8.9972.2 GM.GM3624MGM6093M GM6178M GM6180M GM6185M GM6201MGM6208M GM6218M GM6409M GM9613P GM9733PGM9720P GM9920PGMW11M-ST-SGMW3059 GMW2M-ST-S GMW8M-ST-SGMW3032M-ST-S GMW3399M-ST-SGMW3224M-ST-S 9984001998403299840949984121998447299845052.3 Additional. None.Note: Only the latest approved standards are applicable unless otherwise specified.Instructions: Any overall information may be included here (optional).Instructions: List all documents to which references are made. List each reference by identification name or number.Instructions: The following boilerplate shall be used:3 Test Preparation and EvaluationNot Applicable.4 Requirements and Test Procedure4.1 Testing Requirements. Testing requirements of this procedure are based on base metal substrate type (low carbon or high strength steel), the coating type (electrogalvanized, hot dip galvanized, or aluminized), coating alloy (free zinc, zinc alloy, or aluminum alloy), surface quality (exposed (E), semi-exposed (Z) or unexposed (U) surface), and existing or new processing line. For initial approval, the steel producer must furnish information for each grade/ coating designation/ processing line combination desired for approval. GM requires that all suppliers adhere to the fundamental quality systems requirements of QS9000. Suppliers choosing other approaches must be able to show that their quality systems meet the intent of QS9000. 4.2 Restricted and Reportable Substances(GMW3059). All materials supplied to this specification must comply with the requirements listed in GMW3059, Restricted and Reportable Substances. Compliance with the requirements of GMW3059 must be documented with the GMW3059 form, located in the GMW Engineering Materials and Process Standards, and included in all approval package submissions.4.3 Qualification Requirements. Requirements for qualification of uncoated and coated steel per GM6093M, GM6178M, GM6208M, GM6218M, or GM6409M, GMW2M-ST-S, GMW3032M-ST-S, or GMW3399M-ST-S exposed, semi-exposed and/or unexposed surface quality from a specific processing line, are defined in Table 1. Table 1 also defines testing requirements for an approved processing line supplying a new base metal or new higher strength grades, as well as new combinations of approved processing lines and approved base metals. Please note that elements of this approval process may also be used for other sheet steel related specifications.4.3.1 Test Report. The testing and reporting required under this procedure are the responsibility of the company desiring to be qualified. Test data are to be compiled in a booklet form and presented to the GM Sheet Metal Specialist Team. The test report is to be written in English and all data shall be reported in metric SI (Systeme Internationale) units e.g. millimeters (mm), micrometers (m), megapascals (MPa), etc. An electronic submission will be allowed provided it is in one of the following formats: .pdf; .doc; .xls; or .ppt.4.3.2 Rounding Convention. The rounding convention outlined in the appropriate materials specification shall be used to determine significant digits for the data reported.4.4 Approval Process.4.4.1 Approval Initiation - GM. The technical approval process can be initiated by General Motors World Wide Purchasing (GMWWP) establishing a commercial need or the steel producer/processor establishing a technical need within GM for specific products. GMWWP shall contact the chairman of the SMST to initiate the approval process for a steel producer or processor.4.4.2 Approval Initiation - Supplier. A currently approved steel producer or processor can establish a technical need. The steel producer or processor shall contact the chairman of the SMST for support in obtaining technical approval of a new or modified material or process they wish to supply or use. The request shall state which GM standard the change impacts.4.4.3 Approval Champions. When a formal request is received by the Sheet Metal Specialists Team, a team member will be as-signed as the Champion. The Champion will interface between the steel producer and GM on all steel technical issues during the approval process. The Champion will attend all GMWWP meetings and plant visits where technical issues and requirements are discussed.4.4.4 Approval Review Timing. The Sheet Metal Specialists Team will review and evaluate the test data submitted by the steel producer and information obtained by the Champion. Within six weeks after receiving all the data, a decision will be rendered on granting preliminary technical approval. Full technical approval will be given pending a successful plant trial.4.5 Required Testing. Data from the test requirements shown in Figure 1 and defined here must be received from the steel producer to satisfy the requirements of this procedure. All testing is to be done by the steel producer or an accredited laboratory. In some instances, the SMST may require A/B comparison testing of a new material to an already approved material. Some test requirements may be waived at the SMSTs discretion based upon the nature of the submission.4.5.1 Chemical Analysis of Base Steel. The supplier shall submit the ladle analysis for the heat used to make the qualification coil or, at the suppliers discretion, the chemical analysis taken from the qualification coil. In addition, the melt specification for each alloyed element and residual elements shall also be reported.4.5.2 Mechanical Properties. Mechanical property values for yield strength, tensile strength, % total elongation, % uniform elongation, n value and K value are required. The r value shall be reported when it is specified by the base metal specification. Data shall be taken at the head and tail sections of one coil, along with 5 equally spaced sections along the body of the coil. Edge, center, edge tests shall be performed in the transverse, diagonal and longitudinal directions for all seven sampling locations. Digitized engineering stress /strain curves representative of the submitted material must also be provided. The data shall be in either ASCII (tab or comma delimited) or .xls format and contain 50 data points minimum. All mechanical property data shall be determined as described in the base metal specification. If the mechanical property tests are not described in the base metal specification then the following shall be used: The tension testing shall be done in accordance with ASTM A370. Plastic strain ratio, r value, shall be determined at 16 % strain per ASTM E517 as indicated in the base metal specification for those grades with an r value requirement. Strain hardening exponent, n value, and the strength coefficient, K value, shall be determined per ASTM E646 by the slope of the best fit line as indicated in the base metal specification between 10 and 20 % strain or 10 % to end of uniform elongation. Ongoing adherence to the applicable base metal and coating specifications shall be monitored by GMWWP Steel Quality.4.5.3 Microstructure. Microstructure analysis of the base steel is required in one location in both longitudinal and transverse direction, 100X, 500X and 1000X magnification. A microstructure in the transverse direction, 500X and 1000X magnification, showing the plated edge of the galvanized or aluminized sheet shall be provided. Cleanliness and inclusion content per ASTM E45, Method D and grain size per ASTM E112 must be reported.4.5.4 Thickness Characteristics. Sheet thickness of the finished product shall be measured at the centerline and at 25, 50, 100, 150 and 200 mm from each trimmed edge. These thickness measurements shall be reported along with the width of the trimmed sheet and location in the coil from where the measurements were taken. Data shall consist of thickness measurements from at least 20 coils.4.5.5 Coating Mass. When the coating mass of a qualification coil is required, the coating mass shall be determined per ASTM A90 at one coil position, with samples taken from the coil center and both coil edges, and tested by the weigh-strip-weigh method. Data from on-line x-ray fluorescence techniques in accordance with ASTM A754 may also be used. The method used shall be reported. In case of disagreements between the supplier and purchaser, the weigh-strip-weigh method shall be the referee method. 4.5.6 Coating Mass Variability. Coating mass variability data (GM6185M/GMW8M-ST-S and GM6201M/GMW11M-ST-S) shall be provided (edge- center-edge and top and bottom) to determine coil to coil variation of the coating line. Coating mass variation shall be provided for 20 coils using on-line x-ray fluorescence techniques in accordance with ASTM A754. Data shall be furnished for individual coils as well as summarized in histogram form including mean, range, and standard deviation. Data submitted to this requirement shall consist of products similar to, or representative of, the type of product being submitted for qualification approval. When qualifying a new line, coating variability data from 20 coils shall be submitted as soon as possible after initial technical approval is granted in order to complete requirements for full qualification of the coating line. Submission of coating variability data is expected within 3 months from the time of technical approval of the line.4.5.7 Coating Adhesion. Coating adhesion evaluated by bend test at edge center edge location in test coil per and ASTM B571, ASTM A917, and ASTM A653.4.5.8 Coating Analysis. Coating analysis shall consist of photomicrographs of the coating at 1000X (SEM) depicting representative surface morphology. A coating chemical analysis shall also be submitted, and shall consist of a bulk analysis of the coating as deposited on the sheet, the chemical composition of the zinc pot at the time of coating, as well as a microprobe scan or energy dispersive spectroscopy (EDS) through the coating to the base substrate. The operating limits for the zinc pot chemical composition shall also be provided. Reported elements shall include, but not be limited to, aluminum, iron, lead, antimony and zinc. Other elements intentionally added to the coating shall also be reported. The microprobe/ EDS scan shall include surface chemistry, chemistry at one-half thickness of the coating, and at the coating/steel interface. In case of hot dip coatings, the chemistry of the alloy phase at two depths within the alloy layer shall also be reported. In addition, the chemistry limits for the zinc pot shall be included.4.5.9 Surface Texture. When a surface texture evaluation is required, surface roughness (Ra) and peak count PCcm shall be determined at top and bottom of the sheet at edge center edge location per SAE J911, and shall meet the requirements of GM6180M.4.5.10 Electrogalvanized Zinc Crystal Morphology. Electrogalvanized zinc crystal morphology is determined as shown in Appendix A.4.5.11 Zinc Blister Requirement. Zinc blister requirements are determined per the qualifying coating specification, either GM6201M or GMW11M-ST-S.4.5.12 Lubricant Approval. All lubricants or fluids applied to the surface of the steel sheet by the steel producer or processor shall be GM approved per 9984001. This is required to assure that all lubricants/ fluids are compatible with and can be removed by the paint process cleaning systems.4.5.13 Phosphateability. Phosphateability and paint appearance evaluation per 9984001 shall be determined as shown in Appendix B.4.5.14 Weldability. For base metal/coating combinations listed in GM-WS1 the resistance spot weld behavior of coated and uncoated sheet steel shall be determined by the test procedure defined in the document Recommended Practices for Test Methods for Evaluating the Resistance Spot Welding Behavior of Automotive Sheet Steel Materials, ANSI/AWS/SAE D8.997. Test data submitted for qualification shall include a completed ANS/AWS/SAE D8.997 test report (see Section 9 entitled Endurance Test and Annex B) for all metallic coated steels in GM6093M, GM6208M, GM6409M. GMW2M-ST-S, and GMW3032M-ST-S. Endurance testing in Section 9 is not required for uncoated steel. Weld property testing, including current level/range, hold time sensitivity, and metallography/microhardness evaluations per Section 10, Weld Property Tests are required for uncoated and coated materials listed in GM6093M, GM6208M, GM6218M, GMW3032M-ST-Sand GMW3399M-ST-S. For uncoated materials listed in GM6409M and GMW2M-ST-S, only current level/ range and hold time sensitivity evaluations are required. Adaptations to the procedure in Section 10 to permit the simultaneous evaluation of two materials for cur-rent level/current range and hold time sensitivity may be accepted by the SMST provided the supplier contacts the Champion prior to initiation of qualification testing. All weld test reports must indicate if any partial buttons or interfacial weld separations were evident.For base metal/coating combinations not listed in GM-WS1 additional material must be provided to the GM CRW Group for additional weld testing. Please contact your Champion for details.4.5.15 Bake Hardenability. When required by the base metal specification, paint bake hardenability shall be evaluated as described in the base metal specification. 4.5.16 Plant Tryout. Plant tryout is required to assure steel compatibility with plant manufacturing and assembly environment. The steel supplier, with the approval of purchasing, shall work with MFD to arrange the necessary production trial run. Upon completion of the trial, the involved plant(s) are responsible to submit a letter to the Champion indicating the performance of the material through the metal stamping, assembly and, where applicable, painting processes.4.5.17 Secondary Work Embrittlement. Secondary work embrittlement testing per GM9920P is required for all new substrates when the lower mill limit for carbon content is less than 0.015 wt%. In all cases, SWE testing shall be done on samples with less than 0.015 wt% carbon.4.5.18 Product limits. The product limits of the line being approved shall be provided. The information shall include coil width and material thickness ranges for the combination being approved as directed by the Champion.4.5.19 Process Flow Diagram. A process flow diagram is to be provided that will represent the material being qualified. The flow diagram must include the location and identification of all major processing steps. These steps include hot mill, cold mill, anneal (including type), galvanize line, and temper line. Figure 1: Qualification Requirements Uncoated and Coated (GM6185M, GM6201M, GM6178M, GMW11M-ST-S, GMW8M-ST-S) Sheet5 Additional Requirements5.1 Initial Source Approval.5.1.1 No shipment shall be made by any supplier until preliminary technical approval by the Sheet Metal Specialists Team has been obtained.5.2 Inspection and Rejection. All shipments of materi