1、 ENGINEERING MATERIAL SPECIFICATIONDate Action Revisions 2007 03 07 Activated D. JordanPrinted copies are uncontrolled Copyright 2007, Ford Global Technologies, LLC Page 1 of 8 PERFORMANCE, STEEL, SHEET, BORON TREATED, ALUMINIZED, WSS-M99P39-A1 HIGH STRENGTH (NORTH AMERICA APPLICATIONS) 1300 MPa MIN
2、IMUM ULTIMATE TENSILE STRENGTH PERFORMANCE, STEEL, SHEET, BORON TREATED, ALUMINIZED, WSS-M99P39-A2 HIGH STRENGTH (NORTH AMERICA APPLICATIONS) 1400 MPa MINIMUM ULTIMATE TENSILE STRENGTH PERFORMANCE, STEEL, SHEET, BORON TREATED, ALUMINIZED, WSS-M99P39-A3 HIGH STRENGTH (NORTH AMERICA APPLICATIONS) 1550
3、 MPa MINIMUM ULTIMATE TENSILE STRENGTH PERFORMANCE, STEEL, SHEET, BORON TREATED, ALUMINIZED, WSS-M99P39-A4 HIGH STRENGTH (NORTH AMERICA APPLICATIONS) 1600 MPa TYPICAL ULTIMATE TENSILE STRENGTH 1. SCOPE These specifications define performance requirements for a fully killed, fine grained, hot dip alu
4、minized, high strength, boron treated steel fabricated by any of several combined hot forming/die quenching (press hardening) methods. 2. APPLICATION These specifications were released originally for A and B pillar reinforcements, where a high strength-to-weight ratio is required. These specificatio
5、ns apply to parts that may require a roll forming or other cold forming step prior to austentization. Mechanical properties of the fully processed part are a function of the specific press hardening process selected for part manufacture. The complete part fabrication process shall be outlined in det
6、ail in the Process Flow Diagram/PFMEA and maintained in accordance with the documented Control Plan. Mechanical properties are expected to differ from point to point on a press hardened part. Sampling location(s) and orientation(s) for requirements of this specification shall be as specified on the
7、individual Engineering Drawing (see also para. 3.3.) Mechanical properties of the fully processed part, if not covered by this specification, shall be listed in detail as exceptions on the individual part Engineering Drawing. ENGINEERING MATERIAL SPECIFICATIONWSS-M99P39-A1/A2/A3/A4 Printed copies ar
8、e uncontrolled Copyright 2007, Ford Global Technologies, LLC Page 2 of 8 2.1 LIMITATIONS Due to the hardenability response of this material, individual welding schedules must be developed for each application (see also para. 3.9). Austenitization by induction heating is not allowed. Stress relief an
9、nealing or hydrogen bake-out processes (per WSS-M99A3-A) may be necessary for certain process paths and shall be listed in detail in the Suppliers Control Plan. See also paragraph 3.5 De-scaling parts by acid pickling is not allowed. Prior to use, the fully processed part must be evaluated under the
10、 intended application conditions. Compliance with this specification does not imply that the engineered part will function for any potential application on a vehicle. 3. REQUIREMENTS 3.1 STANDARD REQUIREMENTS FOR PRODUCTION MATERIALS Steel suppliers and part producers must conform to the Companys St
11、andard Requirements for Production Materials (WSS-M99P1111-A). 3.2 MANUFACTURING/PROCESS REQUIREMENTS Final material properties in the part shall be achieved primarily by heat treatment (austenitization/quench/temper). Forming of the blank prior to austenitization may be allowed, provided the incomi
12、ng mechanical properties specified in the relevant Engineering Materials Specification are achieved. Austenitization by induction heating is not allowed. The maximum allowable heating rate between 20 C and 700 C is 12 C/s, as measured on the parts. The maximum temperature of the part in the furnace
13、shall not exceed 930 C. Total furnace dwell time shall be 3 to 13 minutes. Quenching shall be accomplished by any method (e.g., coolant-jacketed die, direct water contact) that achieves final part properties and all other affected requirements of these specifications. The specific quenching method a
14、nd materials shall be described in detail in the part Suppliers Control Plan. The minimum allowable cooling rate from the austenitization temperature to 400 C is 27 C/s, as measured on the parts. The microstructure of the steel in the final part shall be effectively 100% tempered martensite with a s
15、mall amount of bainite likely and allowed. Stress relief annealing or hydrogen bake-out processes (per WSS-M99A3-A) may be necessary for certain process paths and shall be listed in detail in the part Suppliers Control Plan. See also paragraph 3.5. De-scaling parts by acid pickling is not allowed. E
16、NGINEERING MATERIAL SPECIFICATIONWSS-M99P39-A1/A2/A3/A4 Printed copies are uncontrolled Copyright 2007, Ford Global Technologies, LLC Page 3 of 8 3.3 MECHANICAL PROPERTIES (fully processed parts) (Location and orientation as shown on Engineering Drawing, 50 mm gauge length, ISO 6892/ASTM E 8M/EN 100
17、02) A1 A2 A3 A4 Ultimate Tensile Strength (MPa) 1300 min. 1400 min. 1550 min. 1600 typ. Yield Strength (MPa) 950 min. 1000 min. 1100 min. 1200 typ. % Elongation 6 typ. 5 typ. 5 typ. 5 typ. Mechanical properties shall be measured on material that has been subjected to the specific and intended press
18、hardening process-representative thermal profile and environmental exposure as well as a simulated paint bake cycle of 175 C for 30 minutes. The complete thermal profile shall be included with the mechanical property data. Mechanical properties shall be measured on tension test specimens sampled fro
19、m location(s) and orientation(s) on the part as identified on the individual Engineering Drawing. The alloyed aluminized coating shall not be removed prior to mechanical property testing. The alloyed aluminized coating thickness shall be included in the calculation of cross-sectional area. To verify
20、 that the minimum strength level is attained in areas of the part from which standard tension test specimens cannot be sampled, a protocol that correlates measured hardness values in those areas with known ultimate tensile strength values shall be included in the part Suppliers Control Plan. Alloyed
21、 aluminized coating shall be removed locally by mechanical means prior to hardness testing of the steel. In cases where different mechanical properties are required in different locations on a part, a complete description of the mechanical property requirements shall be included on the Engineering D
22、rawing. 3.4 FORMABILITY If needed to enable the fabrication of a specific component, restricted tolerances and/or additional property requirements (i.e., the “quality level“ of the steel) shall be developed by the affected manufacturing activity and the steel supplier. Examples include, but are not
23、limited to: restricted yield strength range, restricted gauge tolerance, specified minimum n-value, and specified surface roughness. The “quality level“ of the steel for a specific component: shall not conflict with specified requirements in paragraph 3 of this Engineering Material Specification sha
24、ll be described in detail on the manufacturing activity Sheet 3 (Americas), EU2066 (Ford of Europe), or part Suppliers Control Plan (independent stampers/fabricators) shall be a mandatory extension of these Engineering Material Specifications Steel cleanliness may involve the use of a mutually agree
25、d upon referee method. ENGINEERING MATERIAL SPECIFICATIONWSS-M99P39-A1/A2/A3/A4 Printed copies are uncontrolled Copyright 2007, Ford Global Technologies, LLC Page 4 of 8 3.5 RESIDUAL STRESS A stress relief anneal of 200 +/- 5 C for 30 +/- 5 minutes shall be performed after quenching unless X-ray dif
26、fraction measurements demonstrate that residual tensile stress is not present at any measured location on a part produced by the given press hardening process. Residual compressive stresses are expected and allowed. 3.6 STEEL MICROSTRUCTURE The microstructure of the press hardened steel shall be pri
27、marily tempered martensite, with a small amount of bainite likely and allowed. Retained austenite in the press hardened steel shall be determined and monitored as specified in the individual Engineering Drawing, Engineering Specification, or in the part Suppliers Control Plan. 3.7 DIMENSIONS AND DIM
28、ENSIONAL TOLERANCE The material thickness specified on the Engineering Drawing shall be nominal and shall include both the substrate thickness and the coating thickness. The press hardening process may result in a thickness reduction. The amount of allowable thickness reduction on selected areas of
29、the part shall be identified on the Engineering Drawing. 3.8 COATING PROPERTIES AFTER FINAL THERMAL PROCESSING 3.8.1 Thickness Coating thickness shall be measured on material that has been subjected to the specific and intended press hardening process-representative thermal profile and environmental
30、 exposure. The coating thickness after final processing shall be 40 microns +/- 10 microns in any measured location on each side (except cut edges) as determined in metallographic cross section. 3.8.2 Structure Coating structure shall be determined on material that has been subjected to the specific
31、 and intended press hardening process-representative thermal profile and environmental exposure. The coating shall consist of a series of aluminum-silicon-iron intermetallic compounds, as determined by scanning electron microscopy and energy dispersive x-ray spectroscopic inspection of a metallograp
32、hic cross-section. The coating shall have no free aluminum on the surface, as determined in metallographic cross section and by visual inspection of the coating surface. ENGINEERING MATERIAL SPECIFICATIONWSS-M99P39-A1/A2/A3/A4 Printed copies are uncontrolled Copyright 2007, Ford Global Technologies,
33、 LLC Page 5 of 8 3.8.3 Roughness (FLTM BA 003-01, Taylor-Hobson Surtronic 3P or equivalent stylus-type profilometer) Surface roughness shall be measured on material that has been subjected to the specific and intended press hardening process-representative thermal profile and environmental exposure.
34、 The average surface roughness, Ra, shall be 1.8 4.0 microns, at a 2.5 mm cutoff, at any measured location in any measured direction. The maximum surface roughness, Rt, shall be a minimum of 15 microns, at a 2.5 mm cutoff, at any measured location in any measured direction. 3.8.4 Scale De-scaling pa
35、rts by acid pickling is not permitted. 3.8.5 Adherence The production coating adherence test method and frequency of testing shall form part of the part Suppliers Control Plan. Coating adherence shall be measured on material that has been subjected to the specific and intended press hardening proces
36、s-representative thermal profile and environmental exposure. 3.8.5.1 Adhesive Shear Test (SAE J1523 or ISO 4587) At a frequency to be negotiated with a Product Development Materials Engineering activity and incorporated into the part Suppliers Control Plan, the following shall be completed: When tes
37、ted according to SAE J1523 or ISO 4587 (bonding thickness of 0.25 mm.) using a high strength structural epoxy adhesive such as WSB-M2G388-A (1k) or WSS-M2G373-B (2k), the coating shall remain adherent to the steel substrate up to a minimum shear strength requirement of 10 MPa. Failure shall be withi
38、n the adhesive bond layer (i.e., bond cohesive failure). Failure at the coating/adhesive interface (i.e. adhesive failure), at the coating/substrate interface (i.e., coating adhesive failure), or within the aluminized coating (i.e., coating cohesive failure) is not permitted. 3.9 WELDABILITY Note: D
39、ue to the hardenability response of these materials, individual welding schedules must be developed for each application. Weldability shall be determined on material that has been subjected to the specific and intended press hardening process-representative thermal profile and environmental exposure
40、. The carbon equivalent of material supplied to this specification will always exceed 0.21 wt. %. Consequently, to demonstrate acceptable weldability of the material and part in the specific application, the following must be completed: ENGINEERING MATERIAL SPECIFICATIONWSS-M99P39-A1/A2/A3/A4 Printe
41、d copies are uncontrolled Copyright 2007, Ford Global Technologies, LLC Page 6 of 8 3.9.1 Weld Test A suitable welding test protocol, including steel and coating chemistries, gauge, and stack-up requirements, shall be agreed between the part supplier and the relevant Company activity (e.g., Vehicle
42、Operations Welding). The welding test protocol shall include optical examination of the as-produced welds; no cracks shall be visible at 20x magnification. Disputes regarding the existence of cracks shall be settled by metallographic examination of cross sections at 200x magnification. The welding t
43、est protocol shall include a cross tension test. When tested in pure cross tension, welds shall exhibit no interfacial fracture, regardless of the material gauge (thickness) or strain rate. 3.10 SURFACE FINISH AND APPEARANCE Materials defined by these specifications are described as Class 3 (unexpos
44、ed). The material shall be used only for parts of the vehicle that are concealed during use, per ES-F75B-11007-(*). (* latest level). 3.11 PAINTABILITY (FLTM BI 106-01, ASTM D 2247) Note: Material defined by these specifications does not develop a conventional zinc phosphate conversion coating. Howe
45、ver, paintability testing shall be performed on material that has been subjected to the complete production-intent cathodic electrodeposition process (alkaline cleaning, exposure to zinc phosphate pretreatment chemicals, cathodic electrodeposition). Paintability shall be determined on material that
46、has been subjected to the specific and intended press hardening process-representative thermal profile and environmental exposure (including, e.g., austenitization, quenching, stress relief annealing, shot blasting, welding, oiling.) Materials defined by these specifications are described as Class 3
47、 (unexposed). Parts shall be primed with cathodically electrodeposited epoxy primer in the production-intent paint facility. A high build primer such as WSS-M64J39-A1 is suitable. Parts shall have a wet paint adhesion grade of 0 or 1 as determined by the paint adhesion test per FLTM BI 106-01, Metho
48、d B and ASTM D 2247 (120 h at 100% RH, 38 +/- 2 C, test less than hour after exposure). 3.12 PHOSPHATE COMPATIBILITY TEST At a frequency to be negotiated with a Product Development Materials Engineering activity and incorporated into the part Suppliers Control Plan, the following shall be completed
49、to demonstrate resistance to hydrogen embrittlement in a solution with slow hydrogen recombination kinetics: The phosphate compatibility test shall be performed on a part that has been subjected to the specific and intended press hardening process-representative thermal profile and environmental exposure. ENGINEERING MATERIAL SPECIFICATIONWSS-M99P39-A1/A2/A3/A4 Printed copies are uncontrolled Copyright 2007, Ford Global Technologies, LLC Page 7 of 8 No visible cracks may form on the part when subjected to the following
