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3.
Grades—The specified grades, hardness range, and metallurgical description are shown in Table 1.
4.Hardness星星牛奶咖啡
4.1
The area or areas on the castings where hardness is to be checked should be established by agreement between supplier and purchar.
4.2
The foundry shall exerci the necessary controls and inspection techniques to insure compliance with the specified hardness range. Brinell hardness shall be determined according to ASTM E 10, Test for Brinell Hardness of Metallic Materials, after sufficient material has been removed from the ca
sting surface to insure reprentative hardness readings. The 10 mm ball and 3000 kg load shall be ud unless otherwi agreed upon.
5.Heat Treatment
5.1Unless otherwi specified, castings may be heat treated to the appropriate hardness range.
5.2
Appropriate heat treatment for removal of residual stress, or to improve machinability may be specified by agreement between supplier and purchar.
6.九婴
Microstructure—The graphite component of the microstructure shall consist of at least 80% spheroidal graphite conforming to Types I and II in Figure 1. The matrix microstructure shall consist of either ferrite, ferrite and pearlite, pearlite, tempered pearlite, or tempered martensite or a combination of the. The microstructure shall be substantially free of primary cementite.
TABLE 1—GRADES OF DUCTILE IRON
英语语音
Grade Casting
Hardness Range
Description
D4018170 HB max or as agreed (4.6 BID, min)
Ferritic D4512156–217 HB or as agreed (4.80–4.10 BID)
Ferritic-pearlitic D5506187–255 HB or as agreed (4.4–3.8 BID)
Ferritic-pearlitic D7003241–302 HB or as agreed (3.90–3.50 BID)Pearlitic DQ&T
Range specific
Martensitic
NOTE— Brinell impression diameter (BID) is the diameter in millimeters (mm) of the impression of a 10 mm
ball at 3000 kg load.
FIGURE 1—CLASSIFICA TION OF GRAPHITE SHAPE IN CAST IRONS (FROM ASTM A 247)
7.Quality Assurance—Sampling plans are a matter of agreement between supplier and purchar. The
桑德环卫
supplier shall employ adequate equipment and controls to insure that parts conform to the agreed upon requirements.
8.General
8.1Castings furnished to this standard shall be reprentative of good foundry practice and shall conform to
河谷地貌dimensions and tolerances specified on the casting drawing.
8.2Minor imperfections usually not associated with the structural functioning may occur in castings. The
imperfections are often repairable; however, repairs should be made only in areas and by methods approved by the purchar.
8.3Additional casting requirements, such as vendor identification, other casting information, and special tesing,
may be agreed upon by the purchar and supplier. The should appear as additional product requirements on the casting drawing.
围绕英文
9.Notes青蛙怎么做
9.1Marginal Indicia—The change bar (l) located in the left margin is for the convenience of the ur in locating
areas where technical revisions have been made to the previous issue of the report. An (R) symbol to the left of the document title indicates a complete revision of the report.
PREPARED BY THE SAE IRON AND STEEL T ECHNICAL COMMITTEE DIVISION 9—
AUTOMOTIVE IRON AND STEEL CASTINGS
APPENDIX A
DUCTILE (NODULAR) IRON
(A material description not a part of the standard)
A.1Definition And Classification—Ductile (nodular) iron, also known as spheroidal graphite iron, is cast iron in
which the graphite is prent as spheroids, instead of flakes as in gray iron or temper carbon nodules as in malleable iron.
耳石症是怎么造成的Ductile iron castings may be ud in the as-cast condition, or may be heat treated.
A.2Chemical Composition—The typical chemical composition of unalloyed iron generally conforms to the
following ranges:
T otal carbon 3.20–4.10%
Silicon 1.80–3.00%
Mangane0.10–1.00%
Phosphorus0.015–0.10%
Sulfur0.005–0.035%
Individual foundries will produce to narrower ranges than tho shown. The spheroidal graphite structure is produced by alloying the molten iron with small amounts of one or more elements such as magnesium or cerium.
A.3Microstructure
A.3.1The microstructure of the various grades of ductile iron consists of spheroidal graphite in a matrix of either
ferrite, pearlite, tempered pearlite, tempered martensite, or certain combinations of the. The relative amounts of each of the constituents is dependent upon the grade of material specified, casting design as it affects cooling rate, and heat treatments, if any.
A.3.2The matrix microstructure of as-cast ductile iron depends to a great extent on the solidification rate and cooling
rate of the casting, as shown in Figure A1. If a ction solidifies rapidly, especially ctions of 0.25 in (6mm) or less, an appreciable amount of carbide may be prent in the casting. If a ction cools slowly, as in a massive, heavy casting, a largely ferritic matrix may result.
FIGURE A1—EXAMPLE OF MICROSTRUCTURAL VARIATION WHICH MAY OCCUR IN AS-CAST CONDITION AS FUNCTION OF METAL THICKNESS (THA T IS, SOLIDIFICA TION RA TE)
A.3.3Alloying elements can also alter the microstructure usually resulting in incread amounts of pearlite. Large
variations in structure can be eliminated or minimized by modifying the casting design or the runner system or both, or by controlled cooling, or any combination of the. Primary carbides, and/or pearlite can be decompod by appropriate heat treatments.
A.3.4A rim may occur on heat treated castings consisting of a graphite-free layer sometimes containing more or less
combined carbon than the underlying material.
A.3.5Typical microstructure of the grades of ductile iron are as follows:
D4018 is annealed ferritic ductile iron. The annealing time and temperature cycle is such that primary carbides, if prent in the as-cast structure, are decompod, and the resulting matrix is ferritic as shown in Figure A2.
