1、 ENGINEERING MATERIAL SPECIFICATION Date Action Revisions Rev. 01 2016 07 29 Revised See sect.5. for revision summary D. Ruhno, J. Schenk, NA 2007 02 22 Activated D. Jordan, NA Controlled document at www.MATS.com Copyright 2016, Ford Global Technologies, LLC Page 1 of 7 STEEL, SHEET, BORON TREATED,
2、ALUMINIZED, HIGH STRENGTH WSS-M1A357-A1 1. SCOPE The sheet metal material defined by this specification is applicable for the direct press hardening (combined hot forming/die quenching) production process. The metallurgical concept conforms to cold rolled, fully killed, fine grained, boron treated s
3、teel. The steel substrate is hot dip aluminized coated (AlSi coated). Typical thickness range is 0.8 mm to 2.5 mm. The material specification defines the properties of the sheet material as delivered to the press-shop in the soft condition before press hardening. Fully processed press hardened part
4、requirements like mechanical properties or final coating layer structure shall meet the performance specification WSS-M99P39-A1/A4 Flexibly rolled (Tailor Rolled Blank) material used for direct press hardening is covered by this specification, see paragraph 3.7 for details. Tailor Weld Blanks may in
5、clude a section made from material to WSS-M1A357-A1. The material callout section of the drawing has to show the material used for all sections and refer to the Ford Engineering Specification for TWB and additional requirements listed there. 2. APPLICATION This material specification was released or
6、iginally for use in AlSi coated direct press-hardened body structure parts. 2.1 LIMITATIONS See the WSS-M99P39-A1 performance specification for the description and limitations of direct press hardening part production processes. The aluminized steel sheet metal material specified herein shall not be
7、 used for indirect hot forming / press hardening processes with significant cold (pre-) forming prior to austenitization because of the limited ductility of the coating layer. 3. REQUIREMENTS 3.1 APPROVED SOURCES This specification requires the use of approved sources. Only the sources identified on
8、 the Ford Approved Source List (ASL) can be used when this specification is listed on the drawing, CAD file, or other documents. The list of approved sources is located within Ford at or available externally through a Ford Materials Engineer. Steel suppliers have the responsibility to supply raw ma
9、terial which enables the direct hot-forming process. The raw material must be capable to achieve the specified strength and performance for the hardened condition using state of the art press hardening tools and processes. This needs to be demonstrated during the material approval process. For initi
10、al approval requirements see paragraph 4.1. Page 2 of 7 Copyright 2016, Ford Global Technologies, LLC ENGINEERING MATERIAL SPECIFICATION WSS-M1A357-A1 3.2. DIMENSIONS AND DIMENSIONAL TOLERANCES 3.2.1 Thickness and Thickness Tolerances The material thickness specified on the Engineering Drawing shall
11、 be nominal and shall include both the substrate thickness and the coating thickness. The nominal incoming material thickness in each area or plateau of multiple- thickness blanks (e.g., tailor welded or tailor rolled blanks) shall be identified on the Engineering Drawing. Tailor rolled blanks shall
12、 include plateau transition position / length tolerances on the drawing. Specified Nominal Tolerance (mm) Thickness (mm) Cold Rolled 0.8 1.19 +/- 0.07 1.2 1.49 +/- 0.08 1.5 1.99 +/- 0.09 2.0 2.59 +/- 0.11 2.6 3.00 +/- 0.14 Note: Refer to WSS-M99P39-A1/A4 for the allowable thickness reduction resulti
13、ng from the press hardening process. 3.2.2 Other Dimensional Tolerances Length, width, flatness, camber, and mass tolerances for the material as delivered by the steel supplier are defined by the relevant national standards and/or regional Ford requirements. Details will be agreed between material s
14、upplier and the parts producer. 3.3 MANUFACTURING/ PROCESS REQUIREMENTS Final material properties in the part are achieved by heat treatment. Detailed process requirements and process parameter limitations for the direct hot forming / press hardening process are provided in WSS-M99P39-A1/A4. 3.4 CHE
15、MICAL COMPOSITION The chemical composition applies for all material delivered to this material specification (wt.-%) C 0.20 0.25 Mn 1.10 1.40 P 0.025 max S 0.008 max Si 0.50 max Cr 0.35 max Mo 0.35 max B 0.005 max N 0.009 max Al 0.02 0.06 (*) Ti 0.02 0.05 (*) Cu 0.2 max Ca * Ni, Sn, Nb, V * Page 3 o
16、f 7 Copyright 2016, Ford Global Technologies, LLC ENGINEERING MATERIAL SPECIFICATION WSS-M1A357-A1 * Sufficient to fully kill the steel. * Sufficient to stabilize nitrogen. * Sufficient for sulfide inclusion shape control * No requirement. All listed elements shall be reported for material source ap
17、proval and shall be listed on the steel Suppliers Control Plan if added intentionally. The upper and lower limits for each of the controlled elements shall be established by the Supplier and included in the steel Suppliers Control Plan. Sulfide inclusion shape control is required and shall be accomp
18、lished by calcium additions. Typical calcium content is 0.0010.005 -wt. %. See paragraph 4.3 for Restricted Substances Management. 3.5 MICROSTRUCTURE The material microstructure in an as delivered condition shall be fine grained, predominantly ferrite-perlite with some carbides present. The grain si
19、ze shall be uniformly distributed along the sheet thickness. The steel sheet shall be free from internal defects that adversely affect manufacturing or part functionality. Examples of defects may include: pipe laminations, non-metallic inclusions, segregation, and blowholes. Non-metallic inclusion c
20、ontent shall not exceed a rating of 2.0 for thin and 2.0 for heavy when tested in accordance with ASTM E45 Method D, Plate III, by analysis at 100X or other method if agreed with regional Ford Materials Engineering. Occurrence and type of material inhomogenities (eg. martensite lines, slag inclusion
21、s, sulfide inclusions, segregation) should represent the state-of-the-art technology and should be limited in size and frequency to ensure a proper production quality and proper performance (crash, fatigue) of the finished part. 3.6 MECHANICAL PROPERTIES (ASTM E8M, ISO 6892-1) For initial approval r
22、equirements see paragraph 4.1. Note: The mechanical properties of direct hot formed / press hardened parts correspond to the martensite microstructure of the material after austenitization / die quench processing. The requirements for the material properties after press-hardening are given in the WS
23、S-M99P39-A1/A4 performance specification and added to the part drawing. The set of properties given in the paragraph below describe the raw material which is shipped directly from steel suppliers to the direct press hardening operation (see paragraph 3.7 for Tailor Rolled Blanks, TRB). Mechanical pr
24、operties listed are valid in both transverse and longitudinal test direction. The cross sectional area for stress calculation shall be defined as that of the measured sample including the steel substrate and the coating. The tensile test has to be done acc. to ASTM 8M (50 mm) or ISO 6892-1 (80 mm).
25、Yield Strength is defined as 0.2% proof stress. Certification of ongoing production material shall be in accordance with regional and/or local requirements (e.g. test direction) and agreed between supplier and receiving operation. Yield Strength 335 550 MPa Ultimate Tensile Strength 500 700 MPa Tota
26、l Elongation 12% min The actual production statistics will be monitored during source approval process and production line specific tighter property ranges may be agreed. Page 4 of 7 Copyright 2016, Ford Global Technologies, LLC ENGINEERING MATERIAL SPECIFICATION WSS-M1A357-A1 3.7 Flexible Rolling (
27、Tailor Rolling or Variable Rolling) The flexible rolling process reduces both the original steel substrate and the AlSi coating thickness and affects the microstructure of the base material and the morphology of the coating layer (both before and after heat treatment). The mechanical properties of t
28、he work hardened, as rolled, material are significantly different compared to non-rolled, as delivered, steel material defined in paragraph 3.6. The blank suppliers control plan must address the potential for damage to the coating as a result of the rolling process and identify acceptable testing me
29、thods to insure coating integrity. Potential issues include, but are not limited to scratches, delamination and bare spots. The properties which are changed by tailor rolling need to be monitored on an individual part basis. It has to be ensured that all the rolled material characteristics meet the
30、process needs to finally achieve the requirements of WSS-M99P39 and any additional requirements listed on the part drawing. The coating thickness range may need a part specific definition if the rolling degree of one or more TRB sections requires this. Note: The final performance of the coating with
31、in the press hardening process might be affected by the flexible rolling process. Details have to be agreed and validated during the material selection, specification compilation and DV/PV processes. Part and material suppliers and Ford STA engineering will define part specific control plans includi
32、ng nominal values and variation ranges for coating thickness and metallurgical properties. Only substrate initially coated to AS 150 requirements shall be used for the production of Flexible Rolled blanks. The coating thickness requirements will vary at each plateau and will be calculated from the o
33、riginal AS 150 requirements minus the percentage of cold reduction at that plateau, e.g., a plateau with the gauge reduced 30% results in a coating thickness range of about 14 22 m. Coating mass range is calculated in a similar manner. In no case is the minimum coating thickness allowed to be lower
34、than 10 m. See WSS-M99P39-A1/A4 (paragraph 3.8) for additional Flexible Rolling requirements after heat treatment. 3.8 FORMABILITY The quality level of the steel supplied to fabricate a specific component shall be negotiated between the part supplier and the steel supplier. Steel cleanliness may inv
35、olve the use of a mutually agreed upon referee method, see paragraph 3.5. Acceptance of subsequent orders by the part supplier for a given component at the agreed upon quality level implies that all components contain steel of a comparable quality level and will form components satisfactorily as def
36、ined by the part supplier. The quality level agreement must not be in conflict with the requirements listed in the performance specification WSS-M99P39-A1/A4. 3.9 JOINABILITY The carbon equivalent of material supplied to this specification will always exceed 0.21 wt%. Consequently, to demonstrate ac
37、ceptable weldability of the material and part in the specific application for the material approval process, the JOINABILITY paragraph of WSS-M99P39-A1/A4 shall be completed. Page 5 of 7 Copyright 2016, Ford Global Technologies, LLC ENGINEERING MATERIAL SPECIFICATION WSS-M1A357-A1 3.10 SURFACE FINIS
38、H AND APPEARANCE The surface quality of material defined by this specification is described as “U” (Unexposed, alternatively called Class 3 in previous specifications). The material shall be used only for parts of the vehicle that are concealed during use, per ES-F75B-11007. 3.10.1 Aluminum-Silicon,
39、 Aluminized Coating The incoming steel shall have been coated by a continuous hot dip aluminizing process. Aluminizing of individual blanks or parts is not allowed. The material shall be uniformly coated and free from defects such as blisters, flux, and uncoated spots. Aluminum coating, with the com
40、position shown below, is required (equivalent to Type 1 per ASTM A463). Typical Coating Composition (Al-Si bath): Si 5 11 wt.% Fe 4.5 wt.% max. Other impurities 0.5 wt.% max. Al Balance The coating composition and coating layer thicknesses as found on the coated steel strip needs to be reviewed and
41、documented during initial source approval of the line. * Previous versions of this specification did not include two coating thicknesses and described only AS 150. This coating designation is an industry term not currently described in ASTM or ISO standards. New call-outs need to include a coating d
42、esignation. * ASTM A90 should be suitably modified to allow coating mass determinations on individual sides. Note: Thickness of the aluminized layer should be measured by metallographic cross-section at any location, except cut edges. 3.10.2 Coating Bend Test (FLTM BI 009-05) No flaking of the as-co
43、ated aluminized coating is allowed when tested with the following modifications: - The bending die is to be two times the thickness of the steel panel - Flaking of the coating within 6 mm of the blank edge shall be disregarded Coating Designation * Type Coating Class Coating Mass per Side (Single Sp
44、ot Test) ASTM A90 * (g/m2) Total Coating Thickness (m) (includes Interfacial Layer) Density (g/cm3) AS 150 AS 150 60 100 20 - 32 3.0 AS 80 AS 80 30 65 10 - 20 3.0 Flexibly Rolled Blank: See para 3.7 Page 6 of 7 Copyright 2016, Ford Global Technologies, LLC ENGINEERING MATERIAL SPECIFICATION WSS-M1A3
45、57-A1 3.11 PAINTABILITY No paint performance criteria for raw material. Processed part shall comply with WSS-M99P39-A1/A4. For initial approval requirements see paragraph 4.1. Acceptance of subsequent orders by the steel supplier for a given component at the agreed upon quality level implies that al
46、l steel supplied will be of a comparable quality level and can be painted satisfactorily as defined and recorded by the manufacturing activity. 3.12 FINISHED PART REQUIREMENTS Mechanical properties, coating layer thickness / structure and surface quality in the fully processed part shall comply with
47、 WSS-M99P39 and any additional requirements listed on the Engineering Drawing. 4. GENERAL INFORMATION The information given below is provided for clarification and assistance in meeting the requirements of this specification. Contact for questions concerning Engineering Material Specifications. 4.1
48、 APPROVAL OF MATERIALS Suppliers desiring approval of their materials shall first obtain an expression of interest from Purchasing, Design or Product Development, and Materials Engineering. The supplier shall submit a completed copy of their laboratory test reports, signed by a qualified and authori
49、zed representative of the test facility, demonstrating full compliance with all the requirements of the Material Specification. Tested material samples must be available for review upon request and kept for a minimum of one year. Upon request, the supplier will review the associated quality control documents (Process Failure Mode and Effects Analysis, Control Plans, Certification testing) with Ford. 4.2 SUPPLIERS ONGOING RESPONSIBILITY All materials must be equivalent in all characterist
