Chrysler Group LLC Document Number: MS-264<S> Material Standard Date Published: 2010-06-09 Category Code: B-1 Change Level: AE EASL Requirement: Yes
Restricted: No
HIGH STRENGTH AND STRUCTURAL QUALITY STEELS - SHEET, STRIP, PLATE, FLAT BAR AND
WELDED MECHANICAL TUBING
1.0 GENERAL
CAUTION: Fasteners, springs or clips manufactured from this material that are surface treated to improve their cleanliness, appearance or corrosion resistance, may become hydrogen embrittled when expod to the chemicals and coating methods ud in processing. Conquently, if the parts are surface treated, it is required that they be hydrogen embrittlement relieved according to the procedures described in PS-9500<S>.
1.1 Purpo of the Standard
This standard specifies the requirements for medium strength, high strength and ultra high strength col
d rolled or hot rolled sheet, strip, plate and welded tubing. This standard follows much of the format and nomenclature of SAE-J1392 and SAE-J2340 but is different in veral respects.
1.2 Purpo of the Material
High strength and structural quality steels are intended for u on parts which require specific minimum mechanical properties in order to meet applicable performance and safety standards. Typical applications include body panels, body structure components, bumpers, reinforcements, and chassis components.
1.3 Coverage of the Standard
High strength and structural quality steels are specified by strength level, type, and deoxidation practice. Available grades range from 25 ksi (172 MPa) to 120 ksi (827 MPa) minimum yield strength. Ultra-high strength, martensitic grades are specified by minimum tensile strength. Available grades range from 190 ksi (1300 MPa) to 220 ksi (1500 MPa). Formability of high strength materials can be more challenging than with low carbon mild steels becau of greater springback concerns and reduced ductility. Advanced High Strength Steels (AHSS) include dual pha steels, partial martensitic steels, and TRIP steels, and are specified by minimum tensile strength. Available
grades range from 490 MPa to 980 MPa minimum tensile strength materials.
Inclusion shape controlled grades as well as other chemistry requirements may be specified when special considerations apply, i.e., freedom from aging and stretcher strains or specific properties needed for dimensional control and forming. Most – if not all - automotive sheet steels are fully killed, and most of the are continuously cast.
High strength and structural quality steels achieve their properties through chemical composition and special thermo-mechanical processing and are generally not suitable for heat treatment by the part manufacturers. Subjecting the grades to heat treatment may lower the mechanical properties. Metallic Materials Engineering shall be consulted to specify the proper grade if annealing, normalizing, stress relief, or welding is to be performed.
2除以0等于多少星星是怎么形成的This standard covers the mechanical properties, chemical composition, weldability, cleanability, and surface requirements for high strength steels.
1.4 Correlation to Other Standards
懵懂什么意思
Sheet and strip furnished under this standard shall conform to the applicable requirements designated by ASTM A-568(M), A-1008(M), A-1011(M), or A-749(M) as appropriate.
Tubing furnished under this standard shall be electric resistance welded and conform to the applicable requirements designated by ASTM A-513. The ba sheet stock properties may be specified for certain part applications in addition to finished tube yield strengths.
2.0 MATERIAL CHARACTERISTICS
2.1 Mechanical Properties<S>***
Material supplied under this standard shall meet the mechanical properties as designated by the type of steel (fourth character – e example under ction 2.2) and strength level code (first three characters - e examples under ction 2.3) specified in TABLE 1. Minimum tensile strength and elongation for lected structural (S) and HSLA (X) steels are listed in TABLES 2 and 3. Dual pha (D), Partial Martensitic (P), and TRIP (T) steels will be specified by minimum tensile strength, and required overall properties are prented in TABLE 4, 5, and 6. Ultra-high strength, martensitic (M) steel will be specified by minimum tensile strength, and guidelines for typical yield strength for a particular minimum tensile strength are shown in TABLE 7. As-received minimum yield strength, bake hardening index, and expected tensile strength for bake hardenable (HK) steel are listed in TABLE 8.
2.2 Code Designation
2.2.1 Strength Level (First, Second, & Third Character - Number Codes)
2.2.1.1 Strength - Sheet, Strip, Plate and Flat Bar
Sheet, strip, plate and flat bar strength shall be specified for steels in the incoming, unformed condition, with a standard sheet or bar-type test specimen, taken in the longitudinal/rolling direction, as described in ASTM A-370, unless otherwi indicated. Becau of the unique properties of the dual pha steel, work hardening values should be reported for both 4 to 6% and 10 to 20% strains.
Bake hardenable and dual pha steels shall have yield strength increas due to work hardening from strain imparted during forming and an additional strengthening increment that occurs during the paint-baking process. The “bake hardening index” (BHI) as shown in Figure 1 is an increa in yield strength after 2 percent pre-strain and baking at 350 degrees F (177 degrees C) for 30 minutes.
Standard test specimens will be taken from unstrained/unbaked material in the longitudinal rolling direction per ASTM A-370. Referring to the Figure 1 below, both the bake hardening index (BHI) and the strain hardening index (SHI) of the material can be determined as follows:
BHI = C - B
Where: B = Flow stress at 2% pre-strain
C = 0.2% yield strength or lower yield point after baking @ 350 degrees F (177 degrees C) for
30 minutes
SHI = B - A
Where: A = Initial 0.2% offt yield strength
B = Flow stress at 2% prestrain洗碗的过程
The original specimen area is ud in calculation of all engineering strengths in this test (A, B and C). The total increa in strength from the test is reported as SHI + BHI.
FIGURE 1: BAKE HARDENING INDEX
2.2.1.2 Strength - Welded Mechanical Tubing
鲁迅名言警句
Tubing strength is defined, as the yield strength required in the finished tube. As defined in ASTM A-370, tubing strength shall be determined with a full size tubular ction or longitudinal strip cut from the tube or pipe, depending on the limits of the test equipment. In instances where the ba yield strength of the incoming flat stock to be ud to form the tube is critical, it may be specified on the drawing instead of the yield strength required in the finished part.
Welded tubing covered by this standard shall have weld flash removed from the outside diameter. Inside diameter weld flash shall not exceed the limits called out in the applicable ASTM Standard, in the engineering drawing, or on the purcha requisition. Tube welds are expected to be functional for the intended u and, where necessary, shall meet the appropriate weld tests as detailed in ASTM A-513 or A-512 Supplementary Requirements.
2.2.2 General Steel Types
The general type of steel is designated by the following 6 categories, each reprenting a compositional/microstructural system or special characteristic as noted below:
Code S: Plain Carbon Structural Steel
Code X: High Strength, Low Alloy (HSLA) Steel
Code H: Bake Hardenable Steel
Code D: Dual Pha Steel
Code P: Partial Martensitic Steel讲童话故事
Code T: TRIP (Transformation Induced Plasticity) Steel
网络的好处和坏处Code M: Martensitic Steel
2.2.3 Deoxidation Practice吉他谱子
Deoxidation Practice and Sulfide Inclusion Control are specified by one of two letter codes as follows:
