1、 ENGINEERING MATERIAL SPECIFICATION Date Action Revisions Rev. 01 2016 08 24 Revised/N Status A2/A3 N Status, See section 5 for revision summary D. Ruhno, A.Toennessen 2007 03 07 Activated D. Jordan Controlled document at www.MATS.com Copyright 2016, Ford Global Technologies, LLC Page 1 of 14 PERFOR
2、MANCE, STEEL, SHEET, BORON TREATED, ALUMINIZED, WSS-M99P39-A1 HIGH STRENGTH, 1300 MPa MINIMUM ULTIMATE TENSILE STRENGTH PERFORMANCE, STEEL, SHEET, BORON TREATED, ALUMINIZED, WSS-M99P39-A2 HIGH STRENGTH, 1400 MPa MINIMUM ULTIMATE TENSILE STRENGTH NOT FOR NEW DESIGNPERFORMANCE, STEEL, SHEET, BORON TRE
3、ATED, ALUMINIZED, WSS-M99P39-A3 HIGH STRENGTH, 1550 MPa MINIMUM ULTIMATE TENSILE STRENGTH NOT FOR NEW DESIGN PERFORMANCE, STEEL, SHEET, BORON TREATED, ALUMINIZED, WSS-M99P39-A4 HIGH STRENGTH, ULTIMATE TENSILE STRENGTH DEFINED ON PRINT 1. SCOPE These specifications define performance requirements for
4、 a fully killed, fine grained, hot dip aluminized, high strength, boron treated steel used to form direct press hardened parts. The standard production method combines furnace heating of blanks that are formed hot and die quenched. Use in conjunction with material specification WSS-M1A357-A1. 2. APP
5、LICATION These specifications were released originally for AlSi coated direct press-hardened body structure parts. 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 ou
6、tlined in detail 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) of tensile test samples and metallographic sections for
7、 coating thickness / Vickers hardness measurement for validation of requirements of this specification shall be as specified on the individual Engineering Drawing (see also paragraph 3.3.). Mechanical properties of the fully processed part, if not covered by this specification, shall be listed in de
8、tail on the individual part Engineering Drawing using variant A4 as the material callout (see paragraph 4.9). Press hardened parts can be designed with soft zones (including hardness transition areas) where a local area of the part is specified to a lower strength level than the surrounding material
9、. The location(s) and expected attributes of the soft zone are to be called out on the part drawing and the manufacturing process shall be described in detail in the part Suppliers Control Plan. There are 2 different thicknesses of the hot dip aluminized coating covered by this specification and in
10、WSS-M1A357-A1. The AlSi coating will provide protection of the surface during the heating cycle to avoid the formation of scale and (limited) corrosion protection of the finished part. No de-scaling is permitted for parts produced to this specification. The AS150 coating is the standard product for
11、general applications; it offers a certain degree of corrosion protection in the form of a barrier coating. The AS80 coating has a thinner coating and is ENGINEERING MATERIAL SPECIFICATION WSS-M99P39-A1/A2/A3/A4 Copyright 2016, Ford Global Technologies, LLC Page 2 of 14 optionally used in “above belt
12、 line” and/or dry environments if functional requirements are met. Neither coating wt. provides significant galvanic protection in normal automotive environments. 2.1 LIMITATIONS Due to the hardenability response of this material, individual welding schedules must be developed for each application (
13、see also para. 3.9). Stress relief annealing or hydrogen bake-out processes (per WSS-M99A3-A) may be necessary for certain process paths, e.g. if the parts have demonstrated a risk for delayed cracking. If a stress relief anneal is required, all details of the heat treatment have to be listed in det
14、ail in the Suppliers Control Plan, see para 4.7. Prior to use, the fully processed part must be evaluated under the intended application conditions. Compliance with this specification does not imply that the engineered part will function for any potential application on a vehicle. Any subsequent hea
15、t treatment will change the mechanical properties and has to be considered in the part design, test and development processes. 3. REQUIREMENTS 3.1 APPROVED SOURCES This specification is performance based and does not have approved sources. Some aspects of this specification may be used to support WS
16、S-M1A357-A1 source approvals. See paragraphs 4.1. - 4.3 and the accompanying test matrix guideline (see appendix) for qualification requirements, ongoing supplier responsibilities and restricted substance management. Parts supplied according to this specification shall undergo a PPAP qualification p
17、rocess including successful production trials that fully meet end product requirements. Any changes to the heat treatment and/or manufacturing process to which the part was successfully validated, have to be notified by a SREA request and the part properties must be tested and re-qualified to the pr
18、oper Production Part Approval Process (PPAP). See the test matrix in Appendix A for guidance. 3.2 MANUFACTURING/PROCESS REQUIREMENTS Final material properties in the part shall be achieved primarily through the heat treatment of the blank that is heated above the austenitization temperature (fully o
19、r partially as defined by the process) and then formed and rapidly cooled (quenched). Quenching shall be accomplished by any method (e.g. standard coolant-jacketed die, direct water contact) that achieves final part properties and all other affected requirements of these specifications. The specific
20、 quenching method and materials shall be described in detail in the part Suppliers Control Plan. Flexible rolling (a.k.a. tailor rolling, variable rolling) blanks, tailor welded blanks, patch welding, or other methods to locally change thickness are allowed, provided all requirements of this specifi
21、cation are met in all thickness regions or plateaus. 3.2.1 General Material Requirements and Restrictions All test samples used to verify compliance to the material requirements in paragraph 3 have to be taken from material that has been subjected to the specific, complete and intended process repre
22、sentative press hardening thermal profile and environmental exposure (e.g., austenitization, quenching, welding, oiling). ENGINEERING MATERIAL SPECIFICATION WSS-M99P39-A1/A2/A3/A4 Copyright 2016, Ford Global Technologies, LLC Page 3 of 14 Any agreed upon “quality level“ of the sheet steel material u
23、sed for a specific component: Shall not conflict with any specified requirements listed in paragraphs 3 of the Engineering Material Specification (WSS-M1A357-A1) and of this Engineering Performance Specification Shall be described in detail on the manufacturing activity specifications Sheet 3 (Ameri
24、cas), Gbl 2066 (Ford of Europe), or Suppliers Control Plan (independent stampers/fabricators) Shall be a mandatory extension of these Engineering Material Specifications 3.2.2 General Process Requirements and Restrictions: The coating must be protected during uncoiling / blanking to avoid local dama
25、ge or local removal which may cause oxidation during hot stamping or reduce the corrosion protection of the finished part, see paragraph 3.8. The thermal processing of the blank (heating rate, max. blank temperature, total furnace time, transfer time) is a main contributor to the final properties of
26、 the coating layer and the part surface. These have an impact to the productions processes like spot welding or painting or corrosion protection. Coating thickness, hardness, micro-structure and surface roughness are physical parameters which need to be controlled to ensure limited process variation
27、 and optimum product quality. Typical thermal processing parameters ranges are listed in para 4.1, they are for indication only. The final optimum process parameter selection will depend on blank thickness, part geometry etc. and will be documented in the part specific control plan. The maximum temp
28、erature of the blank in the furnace shall not exceed 930 C. The furnace process window has to be adjusted properly to achieve the mechanical properties and ensure that the coating layer and surface quality properties comply with the material and functional requirements listed in paragraphs 3.8 to 3.
29、13. All parts supplied to this specification must be free of hydrogen embrittlement, see paragraph 4.4. Hydrogen generating processes including furnace atmospheres with residual water content or cleaning and/or coating processes with the risk to release hydrogen have to be avoided. See paragraph 4.7
30、. for a recommended dew point control of the furnace atmosphere. The microstructure of the steel in the press hardened part shall be effectively martensite with a small amount of bainite. The edge quality of the final trim process is critical for the finished part performance. Laser cutting/trimming
31、 is recommended, other hard cutting processes must be validated, see paragraph 4.7. Blank / tube austenitization by induction heating is not allowed. De-scaling parts by acid pickling or blasting is not allowed. ENGINEERING MATERIAL SPECIFICATION WSS-M99P39-A1/A2/A3/A4 Copyright 2016, Ford Global Te
32、chnologies, LLC Page 4 of 14 3.3 MECHANICAL PROPERTIES AFTER DIRECT PRESS HARDENING Location and orientation of samples for tensile testing as shown on Engineering Drawing, 50 mm gauge length tested to ISO 6892-1 /ASTM E 8M. A1 A2 A3 A4 Ultimate Tensile Strength (MPa) 1300 min. 1400 min. 1550 min. C
33、all-out Yield Strength (MPa) 950 min. 1000 min. 1100 min. Call-out Total Elongation 5 % min.* 5 typ. 5 typ. Call-out Exception for A1: Elongation 4% min for gauge HV 400, values significantly below that would indicate a non-martensitic microstructure. Note: The hardness requirements for intentionall
34、y softened zones need to be agreed upon between Ford Product Development and the part supplier, documented on the part drawing and addressed in the suppliers control plan. 3.4 FORMABILITY Aluminum-Silicon coated blanks shall not be cold stamped prior to heat treatment. Pre-forming of the material by
35、 roll forming or flexible rolling may be allowed provided the coating is not damaged during the process. See WSS-M1A357-A1, paragraph 3.7 for details. 3.6 STEEL MICROSTRUCTURE The microstructure of the steel in the press hardened part shall be effectively martensite with a small amount of bainite li
36、kely and allowed. Note: Process parameters like temperature of deformation, local strain and strain rate and the quench rate are factors which will affect the local phase transformation path and the resulting fraction of martensite / bainite phases as well as the microhardness. They have to be devel
37、oped and balanced within the process cycle during the part / die design development process. The resulting process parameter window will be documented in the control plan (see paragraph 4.4). Requirements for locally softened zones must be documented on the part drawing including the dimensions and
38、location of the area affected and the expected materials attributes which may include but are not limited to a specific hardness range and/or microstructure. ENGINEERING MATERIAL SPECIFICATION WSS-M99P39-A1/A2/A3/A4 Copyright 2016, Ford Global Technologies, LLC Page 5 of 14 3.7 DIMENSIONS AND DIMENS
39、IONAL 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 in the part as compared to the incoming blank. The amount of allowabl
40、e thickness reduction in selected areas of the press hardened part shall be identified on the Engineering Drawing. 3.8 COATING PROPERTIES AFTER PRESS HARDENING (BEFORE PAINT PROCESSING) Note: The coating must be protected during uncoiling / blanking to avoid local damage or partial removal which may
41、 cause oxidation during hot stamping and/or affect the part performance. See paragraph 3.8.3. 3.8.1 Coating Thickness after Thermal Processing Note: Only substrate initially coated to AS 150 requirements shall be used for the production of Flexible Rolled Blanks. See WSS-M1A357-A1 section 3.7 for de
42、tails. Coating thickness shall be measured at locations which have been identified on the drawing or in agreed upon production control plans. The coating thickness requirements are expected to be valid on both sides of the part at any location with the exception of cut edges. The coating thickness r
43、equirements for press-hardened parts are listed in Table 1. The coating thickness of flexibly rolled blanks will be reduced at each plateau by the same amount as the substrate in that location (i.e. gauge of substrate reduced by 30% = thickness of coating reduced 30%). Therefore, the Total Coating T
44、hickness requirements in Table 1 are also reduced by the degree of cold work for each plateau. The Interdiffusion Layer thickness for flexible rolled blanks shall not exceed 12 m. Photomicrographs of Al-Si coating cross sections after different heat treatments are shown in paragraph 3.8.2., Figure 1
45、. The total coating thickness and the thickness of the interdiffusion layer are marked on the photos to demonstrate the measurement method. Table 1: Coating Designation and Thickness Requirements Coating Designation Condition Total Coating Thickness (m) Interdiffusion Layer (IDL) Thickness (m) AS 15
46、0 Press- hardened 30 - 50 16 AS 80 Press- hardened 15 - 30 12 Note: See WSS-M1A357-A1 for coating weight requirements of the raw material. ENGINEERING MATERIAL SPECIFICATION WSS-M99P39-A1/A2/A3/A4 Copyright 2016, Ford Global Technologies, LLC Page 6 of 14 3.8.2 Coating Structure The coating structur
47、e shall be determined on material that has been subjected to the specific 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 microsc
48、opy and energy dispersive x-ray spectroscopic inspection of a metallographic cross-section. The coating shall have no residual unalloyed aluminum on the surface, as determined in metallographic cross section and by visual inspection of the coating surface. Free metallic aluminium would indicate an u
49、nder-alloyed condition caused by insufficient heating temperature or time. The thickness of the inter-diffusion layer shall be limited to the level indicated in Table 1. Thick inter-diffusion layers indicate unacceptable process conditions, e.g. above limit maximum furnace temperature or extended heating time. See Figure 1 for typical examples of etched microsections and SEM photos of the corresponding surface areas of an AS 150 coating. The coating structure required by this specification shall be similar to Figure 1B, the typical
