1、 WORLDWIDE ENGINEERING STANDARDS Material Specification GMW16615 Steel Tubes and Profiles with Multi-Wall Thickness (TMT) Copyright 2011 General Motors Company All Rights Reserved September 2011 Originating Department: North American Engineering Standards Page 1 of 12 1 Scope This specification cove
2、rs the requirements for heat-treatable or non-heat-treatable extruded low carbon steel tubes with multi-wall thickness (TMT) and profiles used in the manufacture of structural parts requiring low, middle and high strength. The usage of this standard is indicated for applications which require low we
3、ight and high performance. Typical applications include door impact beams, cross car beam, bumper impact beams, reinforcements for impact structures, bull bars and general tubular parts, and specific cases of reduction or elimination of stamping tools by employment of split techniques of symmetrical
4、 TMT profiles according to 3.1.4.3. 1.1 Material Description. The particular application shall determine the extrusion operations to produce the finished steel tube and profile. 1.1.1 Resistance Welded Mechanical Tubing. Primary tubes and profiles supplied to this specification are roll formed from
5、steel strip to the desired shape and dimension, plasma or electrical resistance welded into a tube, and then extrusion process to achieve the desired profile and variable thickness, the heat treated may be made to reach the strength mechanical properties. 1.1.2 TMT Extruded Tubes. Tubes manufactured
6、 by seamless process or rolled steel strip according to item 1.1.1 are submitted in cold extrusion process to construct a desired profile with variable wall thickness. The cold extrusion process causes a work hardening and a mechanical strength improving, for higher strength grades, an induction hea
7、t treatment is performed later to achieve the final mechanical property requirements. The specified grades are low strength with multi-wall thickness (LSTMT) type ferrite + pearlite (FP), medium strength with multi-wall thickness (MSTMT) and high strength with multi-wall thickness (HSTMT) for the th
8、ree types of multi-phases (MP) such as ferrite and pearlite, bainite and/or martensite. The TMT tube final external profile may be circular, square or any other form specified by Product Engineering. The microstructure of the finished tubes may consist of ferrite and pearlite after extrusion operati
9、on and martensite and/or bainite for heat-treatable tubes. 1.1.3 Material Identification. The GMW base metal specification number defines the material designation, steel product type, grade, and finish type. The sheet steel product type for manufactured primary tubes are cold rolled (CR) or hot roll
10、ed (HR) products. The steel grades will correspond to the chemical and mechanical requirements as shown in Tables 1 through 3. The finish type, an alpha character, will be designated with the finish unexposed (U). The descriptive items are used together to form the coding system. Examples of the cod
11、ing system for engineering part drawings, electronic math data files, and/or manufacturing engineering documents are shown in Section 8. GM WORLDWIDE NORTH AMERICA EUROPE LATIN AMERICA ASIA PACIFIC GMW16615-M-ST-T-LS TMT 787T/775Y FP - - - - GMW16615-M-ST-T- MS TMT 1050T/950Y MP - - - - GMW16615-M-S
12、T-T- HS TMT 1475T/1250Y MP - - - - 1.2 Symbols. Not applicable. 1.3 Typical Applications. Typical applications are uncoated or pre-coated thin gauge tubular structural parts or other design products derivates from tubes requiring yield and tensile strengths exceeding 775 MPa and 787 MPa respectively
13、. 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 GMW16615 Copyright 2011 General Motors Company All Rights Reserved September 2011 Page 2 o
14、f 12 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASTM A513 ASTM E1077 ISO 6892 SAE J419 ASTM A751 DIN 50602 JFS A 1001 ASTM E45 ISO 898-1 JIS Z2201 2.2 GM Standards/Specifications. 2.3 Additional References.
15、x TMC003 Material Safety Data Sheet guidance documents (available at ). 3 Requirements The following section defines specific requirements for material on delivery, processing, performance and other stages during life cycle. Deviations required for individual GM business units are listed in Deviatio
16、ns at the end of this document. Parts supplied according to this specification must undergo successful trials that fully meet end-product requirements. In the event of any changes to the heat treatment and/or manufacturing process to which the part was successfully validated, the appropriate enginee
17、ring group must be notified and the part must be re-validated with the new process. 3.1 Requirements on Delivery. 3.1.1 Chemical Requirements. Base metal composition based on product (TMT tube and profile) analysis determined per ASTM A751 shall conform to the requirements of Table 1 and/or shall be
18、 agreed upon between supplier and purchaser. Additional demands and restrictions may be imposed by local Materials Engineering organizations depending on the application. Table 1: Chemical Composition Note 1, Note 2 TMT Tubes and Profiles Grades Element LSTMT; MSTMT HSTMT Carbon 0.25 max. 0.28 max.
19、Manganese 1.6 max. 0.6 to 1.8 Aluminum - 0.01 min. Silicon 0.15 to 0.50 0.15 to 0.80 Phosphorus 0.035 max. 0.035 max. Sulfur 0.04 max. 0.03 max. Chromium 0.25 max. 0.35 max. Nitrogen 0.25 max. 0.15 max. Boron - - Titanium - 0.15 max. Copper 0.025 max. 0.45 max. Molybdenum - 0.08 max. Niobium 0.20 ma
20、x. 0.26 max. Vanadium 0.25 max. 0.25 max. Note 1: Chemical composition based on product (coil or sheet/blank, tube) analysis. Note 2: max. = maximum, min. = minimum GMW3011 GMW14019 GMW14729 GMW16549 GMW3059 GMW14700 GMW14829 GMW3335 GMW14704 GMW16170 Copyright General Motors Company Provided by IHS
21、 under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16615 Copyright 2011 General Motors Company All Rights Reserved September 2011 Page 3 of 12 3.1.2 Mechanical Requirements. Table 2: Mediu
22、m and Low Strength Extruded Tubular Product Mechanical Properties Note 1 Mechanical Property Requirements TMT Tube and Profile Condition Designation Yield Strength at 0.2% Offset (MPa) Tensile Strength (MPa) Total Elongation (L0 50 mm) Total Elongation (L0 80 mm) Grade GMW16615-M-ST-T-LSTMT-787T/775
23、Y-FP minimum 775 minimum 787 minimum 7% minimum 6% Grade GMW16615-M-ST-T- MSTMT-1050T/950Y-FP minimum 950 minimum 1050 minimum 7% minimum 6% Note 1: Mechanical properties are measured conform to 3.1.2.1. Table 3: High Strength Extruded Tubular Product Mechanical Properties Note 1 Mechanical Property
24、 Requirements TMT Tube and Profile Condition Designation Yield Strength at 0.2% Offset (MPa) Tensile Strength (MPa) Total Elongation (L0 50 mm) Total Elongation (L0 80 mm) Grade GMW16615-M-ST-T- HSTMT-1475T/1250Y-MP minimum 1250 minimum 1475 Minimum 6% minimum 5% Note 1: Mechanical properties are me
25、asured conform to 3.1.2.1. 3.1.2.1 Tension and Yield Strengths. Post-form not heat treated and heat treated products TMT extruded tube shall adhere to the requirements in Tables 2 and 3. The 0.2% Offset Yield Strength, Tensile Strength and Percent Total Elongation shall be determined in the longitud
26、inal direction per GMW3335 for cold-formed samples. The test direction is not critical for heat treated TMT tube and profile. The usage of samples per ISO 6892 Type I (50 mm gage length ASTM type sample) or ISO 6892 Type II (80 mm gage length DIN type sample), or JIS Z2201 (No. 5) shall agree with P
27、roduct Engineering. For work hardened TMT tubes and profiles, as grade LS TMT, the work hardening may vary at different transversal points in a section; mainly in TMT tube and profile with small diameters or considerate variations of thicknesses. Then, for these cases, it is recommended the tension
28、test performed direct in the tube, and the transversal profile area shall be specified on product drawing as test reference. For heat- treated TMT Tube and profile or in general parts of excessive size, the tests may be made in specimens if agreed with the Product Engineering. Desired mechanical pro
29、perties different from those specified in Tables 1 and 2 and required for a specified application condition only can be used in agreement with the Product Engineering for attending any particular case. For this case, the Product Drawing shall specify it at the material and test fields. 3.1.2.2 Bendi
30、ng Strength. For tubular parts used in safety components which require a desired bending strength are to meet safety federal standards as Federal Motor Vehicle Safety Standards (FMVSS) and Economic Commission for Europe (ECE) regulations. Specification of bending load per dislocation shall be specif
31、ied on product drawing for tube and profile with multi-wall thickness. The bending load specification shall be determined by Finite Element Analysis (FEA) or experimentally during the product homologation phases. For this case, the constructed physical TMT tube and profile shall be tested using bend
32、ing equipment, and its performance evaluated in a plot of a load-displacement graph so the bending specifications are obtained from this graphic. The test typical instrumentation setup shall be carried out according to Figure 1, which shows the sketch of bending test equipment. The drawing specifica
33、tion determines the minimum load from a certain bending displacement (d) up to final displacement, as follows: Typical illustrative example for being used as a drawing specification methodology (see also the Appendix A): Only as reference: the following is an example of a bending specification. Load
34、 of 306 kg minimum from 50.8 to 101.6 mm of displacement. 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 GMW16615 Copyright 2011 General Mo
35、tors Company All Rights Reserved September 2011 Page 4 of 12 No visible tube collapse is allowed between specified ranges of displacements (d) during bending test. At Figure 1, note three component contact points: a dynamic punch and two static support, the loading device consist of a rigid, steel c
36、ylinder or semi-cylinder 320 mm (12.6 in) in diameter with the surface continuous and smooth. The TMT tube and profile must be supported on a rigid, horizontal fixture adequately restrained at the bending equipment to prevent lateral and/or rotational movement of the tube during the test. The punch
37、shall apply a load to TMT tube and profile center in a perpendicular direction normal to equipment vertical plane. Apply the load continuously such that the loading device travel rate of 20 mm/minute (0.79 in/minute) until the loading device travels 129 mm (5 in.). At reaching the maximum displaceme
38、nt specified on drawing, no visible crack or breakage is allowed. Unless otherwise specified herein, the test shall be performed at ambient conditions. Note: When the bending test requirements are specified on drawing and the tube length is smaller than 600 mm (26.5 in), the tube supplier shall prod
39、uce samples with length of 750 mm minimum (29.5 in) only for this purpose. Note: For non-symmetrical transversal profiles, the bending test may be performed in any transversal position, unless specified on drawing. Figure 1: Test Equipment Description 3.1.3 Physical Requirements. 3.1.3.1 Material Th
40、ickness and Tolerances. For LSTMT, MSTMT and HSTMT, tubes and profiles require the control of moments of inertia defined in design as a dimensional control, so the detailed engineering part drawing or electronic math data file specify the tube profile and the variable wall thickness. After that, the
41、 moment of inertia referent to defined profile shall be specified on drawing, such as in X and Y directions, such as: Ix/Iy; lx; ly; Wcm. The Wcm is the moment of resistance referent to mass center. The product drawing shall reference the X an Y axes for any TMT tube and profile for moment of inerti
42、a calculations. When moments of inertia and Wcm are not specified on drawing in agreement with Product Engineering, the dimensional tolerances for electric resistance welded tubes shall follow ASTM A513. 3.1.3.2 Surface Requirements. 3.1.3.2.1 Pretreatment/Paintability. For painted applications the
43、surface shall be capable of achieving a high quality zinc phosphate conversion coating according to GMW3011 (for crystal size and coating weight) and also capable of meeting the requirements of GMW16170 “Thin Film; Nanometers Thick (NT) Pretreatment”. The adhesion of the E-coat must fulfill the test
44、 requirements of the crosshatch test according to GMW14829 (requirement: rating 0, as-received and after 120 h humidity exposure per GMW14729) and the delamination test according to GMW14704 (Rating 0 or 1 after 48 h test duration) for paint adhesion. For fully painted applications on exposed (E) su
45、rfaces, the material shall meet the requirements of the stone chip resistance test according to GMW14700, Method A (or B) and Method C, with a minimum stone impact resistance rating of 8. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo repro
46、duction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16615 Copyright 2011 General Motors Company All Rights Reserved September 2011 Page 5 of 12 3.1.3.2.2 Adhesive Compatibility. Surfaces of the pre-coated and uncoated flat products and/or finished parts
47、 furnished to this specification shall be capable of being adhered with the respective adhesives specified for the specific application. Adhesive Compatibility shall be tested according GMW16549. Deviations from this requirement need to be agreed by Materials Engineering and Product Engineering. 3.1
48、.3.3 Microstructure. 3.1.3.3.1 Inclusions. Two (2) optional methods for analysis are available. There should be an agreement with the local business unit which of the two following methods is to be performed: Method A: ASTM E45 Method D, Plate III, by analysis at 100x inclusion content shall not exc
49、eed a rating of 2.0 for thin and 2.0 for heavy. Method B: DIN 50602 technique M: by analysis, inclusions shall not exceed size index 3; in case of diameters smaller than 20 mm, they shall not exceed size index 2. 3.1.3.3.2 Surface Decarburization. Total (complete) surface decarburization exceeding 0.05 mm is prohibited as defined by ISO 898-1, ASTM E1077, or SAE J419 Type 1. 3.1.3.3.3 Heat Affected Zone (HAZ). Depending on primary tube material,
