ASTM A800/A800M-91(1997)e1
(Practice)Standard Practice for Steel Casting, Austenitic Alloy, Estimating Ferrite Content Thereof
Standard Practice for Steel Casting, Austenitic Alloy, Estimating Ferrite Content Thereof
SCOPE
1.1 This practice covers procedures and definitions for estimating ferrite content in certain grades of austenitic iron-chromium-nickel alloy castings that have compositions balanced to create the formation of ferrite as a second phase in amounts controlled to be within specified limits. Methods are described for estimating ferrite content by chemical, magnetic, and metallographic means.
1.2 The grades covered by this practice are: CF-3, CF-3A, CF-8, CF-8A, CF-3M, CF-3MA, CF-8M, CF-8C, CG-8M, and CH-10.
1.3 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the practice.
1.4 This standard does not purport to address the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use .
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e1
Designation: A 800/A800M – 91 (Reapproved 1997) An American National Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Practice for
Steel Casting, Austenitic Alloy, Estimating Ferrite Content
Thereof
This standard is issued under the fixed designation A 800/A800M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Keywords were added and Table X1.2 corrected editorially in September 1997.
1. Scope E 353 Test Methods for Chemical Analysis of Stainless,
Heat-Resisting, Maraging, and Other Similar Chromium-
1.1 This practice covers procedures and definitions for
Nickel-Iron Alloys
estimating ferrite content in certain grades of austenitic iron-
E 562 Practice for Determining Volume Fraction by Sys-
chromium-nickel alloy castings that have compositions bal-
tematic Manual Point Count
anced to create the formation of ferrite as a second phase in
2.2 Constitution Diagrams:
amounts controlled to be within specified limits. Methods are
Schoefer Diagram for Estimating Ferrite Content of Stain-
described for estimating ferrite content by chemical, magnetic,
less Steel Castings (1980 revision)
and metallographic means.
Schaeffler Diagram for Estimating Ferrite Content of Stain-
1.2 The grades covered by this practice are: CF-3, CF-3A,
less Steel Weld Metal
CF-8, CF-8A, CF-3M, CF-3MA, CF-8M, CF-8C, CG-8M, and
CH-10. DeLong Diagram for Estimating Ferrite Content of Stainless
Steel Weld Metal
1.3 The values stated in either inch-pound units or SI units
are to be regarded separately as standard. Within the text, the 2.3 American Welding Society Specification:
SI units are shown in brackets. The values stated in each AWS A 4.2, Procedures for Calibrating Magnetic Instru-
system are not exact equivalents; therefore, each system must
ments to Measure the Delta Ferrite Content of Austenitic
be used independently of the other. Combining values from the Stainless Steel Weld Metal
two systems may result in nonconformance with the practice.
1.4 This standard does not purport to address the safety 3. Terminology
problems, if any, associated with its use. It is the responsibility
3.1 Definitions:
of the user of this standard to establish appropriate safety and
3.1.1 ferrite—the ferromagnetic, body-centered, cubic-
health practices and determine the applicability of regulatory
microstructural constituent of variable chemical composition in
limitations prior to use.
iron-chromium-nickel alloys. This may be formed upon solidi-
fication from the molten metal (delta ferrite) or by transforma-
2. Referenced Documents
tion from austenite or sigma phase on cooling in the solid state
2.1 ASTM Standards: (alpha ferrite).
A 351/A351M Specification for Castings, Austenitic, Aus- 3.1.2 ferrite content—the proportion of total volume of an
tenitic–Ferritic (Duplex), for Pressure–Containing Parts iron-chromium-nickel alloy present as the ferrite phase.
A 370 Test Methods and Definitions for Mechanical Testing 3.1.3 ferrite number—the ferrite content expressed as an
of Steel Products arbitrary number based on the magnetic response of the alloy
A 799/A799M Practice for Steel Castings, Stainless, Instru- in a weld deposit.
ment Calibration, for Estimating Ferrite Content 3.1.4 ferrite percentage—the ferrite content expressed as a
A 919 Terminology Relating to Heat Treatment of Metals volume percent.
E 38 Methods for Chemical Analysis of Nickel-Chromium 3.1.5 heat treatment—the definitions in Terminology A 919
and Nickel-Chromium-Iron Alloys are applicable to this practice.
1 5
This practice is under the jurisdiction of ASTM Committee A-1 on Steel, Annual Book of ASTM Standards, Vol 03.01.
Stainless Steel, and Related Alloysand is the direct responsibility of Subcommittee Appendix of this practice.
A01.18 on Castings. Metal Progress Data Book, American Society for Metals, Mid June 1977, p.
Current edition approved Aug. 15, 1991. Published October 1991. Originally 161.
published as A 800 – 82. Last previous edition A 800/A 800M – 90. Welding Journal, American Welding Society, Vol 38, No. 7, July 1973, p.
Annual Book of ASTM Standards, Vol 01.02. 293–s.
3 9
Annual Book of ASTM Standards, Vol 01.03. Available from the American Welding Society, P. O. Box 351040, 550 N. W.
Annual Book of ASTM Standards, Vol 03.05. LeJeune Rd., Miami, FL 33135.
A 800/A800M
NOTE 1—There may be a substantial decrease in the ferrite content of
4. Significance and Use
weld deposits after solution heat treatment in comparison with the
4.1 The tensile and impact properties, the weldability, and
as-deposited value.
the corrosion resistance of iron-chromium-nickel alloy castings
may be influenced beneficially or detrimentally by the ratio of 6. General Caution
the amount of ferrite to the amount of austenite in the
6.1 In specifying ferrite content as required in 5.1.3, the
microstructure. The ferrite content may be limited by purchase
purchaser should not set limits that conflict with applicable
order requirements or by the design construction codes gov-
material specification requirements: for example, a maximum
erning the equipment in which the castings will be used. The
limit of 10 % ferrite for Grade CF-3A in Specification A 351/
quantity of ferrite in the structure is fundamentally a function
A 351M for which the minimum tensile strength requirement is
of the chemical composition of the alloy and its thermal
77 ksi [530 MPa].
history. Because of segregation, the chemical composition,
6.2 When Supplementary Requirement S1 is specified, the
and, therefore, the ferrite content, may differ from point to
purchaser should set ferrite content limits that are compatible
point on a casting. Determination of the ferrite content by any
with the measuring instrument to be used.
of the procedures described in the following practice is subject
7. Estimation of Ferrite Content
to varying degrees of imprecision which must be recognized in
7.1 Estimation in the base metal of the casting by chemical
setting realistic limits on the range of ferrite content specified.
composition in accordance with the Schoefer diagram (see
Sources of error include the following:
Appendix):
4.1.1 In Determinations from Chemical Composition—
7.1.1 A chemical analysis of the heat from which the
Deviations from the actual quantity of each element present in
castings are poured shall include the following elements
an alloy because of chemical analysis variance, although
whether or not required by the chemical requirements of the
possibly minor in each case, can result in substantial difference
product specification: carbon, manganese, silicon, chromium,
in the ratio of total ferrite-promoting to total austenite-
nickel, molybdenum, columbium, and nitrogen.
promoting elements. Therefore, the precision of the ferrite
7.1.1.1 Upon written agreement between the purchaser and
content estimated from chemical composition depends on the
the producer, an estimated nitrogen content may be reported
accuracy of the chemical analysis procedure.
instead of an amount determined by analysis of the specific
4.1.2 In Determinations from Magnetic Response—Phases
heat if actual chemical analyses have been made for nitrogen in
other than ferrite and austenite may be formed at certain
a sufficient number of heats of the same alloy type, produced
temperatures and persist at room temperature. These may so
by the same melting practice, to establish the average nitrogen
alter the magnetic response of the alloy that the indicated
content to be expected.
ferrite content is quite different from that of the same chemical
7.1.2 The ferrite content of the casting shall be estimated
composition that has undergone different thermal treatment.
from the central line of the diagram at the composition ratio of
Also, because the magnets or probes of the various measuring
“chromium equivalent” (Cr ) to “nickel equivalent” (Ni )
instruments are small, different degrees of surface roughness or e e
determined from the following formula:
surface curvature will vary the magnetic linkage with the
(Cr(%) + 1.5Si(%) + 1.4Mo(%) + Cb(%) − 4.99)/(Ni(%)
material being measured.
+30C(%) + 0.5Mn(%) + 26(N − 0.02%) + 2.77) = (Cr )/(Ni )
4.1.3 In Determinations from Metallographic
e e
7.1.3 When a product analysis is made by the purchaser, it
Examination—Metallographic point count estimates of ferrite
shall include the elements listed in 7.1.1. If a comparison is
percentage may vary with the etching technique used for
made of ferrite content estimated from a product analysis
identification of the ferrite phase and with the number of grid
performed by the purchaser, with that estimated from the heat
points chosen for the examination, as explained in Test Method
analysis (see 7.1.1), the reproducibility data in the precision
E 562.
statements of Test Methods E 353 shall be used as a guide.
4.2 The estimation of ferrite percent by chemical composi-
7.1.3.1 Methods E 38 or Test Methods E 353, as applicable,
tion offers the most useful and most common method of ferrite
shall be used as referee chemical analysis methods.
control during melting of the metal.
7.2 Estimation in weld deposits by chemical composition in
4.3 For most accurate estimate of ferrite percent, a quanti-
accordance with the Schaeffler or DeLong diagrams:
tative metallographic method should be used.
7.2.1 The ferrite content shall be estimated (a) from the
deposit chemical analysis included on the electrode manufac-
5. Ordering Information
turer’s certified material test report, or (b) from chemical
5.1 Orders for material to this practice should include the
analysis of a weld deposit pad made by the casting manufac-
following as required:
turer.
5.1.1 Applicable ASTM product specification or other docu-
7.3 Estimation of ferrite content in heat, product, or weld
ment covering product requirements,
metal may be made by the magnetic response or metallo-
5.1.2 Alloy grade,
graphic methods by imposition of Supplementary Require-
5.1.3 Required ferrite content range, in volume percent, of
ments S1 or S2, respectively.
the castings after final heat treatment. Also, if desired by the
8. Acceptance Standards
purchaser, required ferrite content range, in ferrite number, for
weld deposits (Note 1) as deposited, and
8.1 Conformance with the required ferrite content range
5.1.4 Supplementary requirements, if any, desired. specified in 5.1.3 as indicated by the estimation procedure of
A 800/A800M
7.1 and 7.2 shall be the basis for acceptance of material was found to meet the requirements.
supplied under this practice unless other methods of estimation
9.2 The test report shall contain the results of the actual
are ordered as supplementary requirements, in which case the
chemical analyses required by 7.1.1 and 7.2.1 and the indicated
supplementary requirement shall be the basis of acceptance.
ferrite content range. The estimates of ferrite content from
8.2 If lack of conformance with the ferrite content range
magnetic measurements (S1) or from point counts (S2), or
specified in 5.1.3 is indicated by a product analysis made by the
both, if ordered by the purchaser, also shall be reported.
purchaser (7.1.3) and by a referee analysis as provided in
9.3 The test report shall be signed by an authorized agent of
7.1.3.1, rejection of material shall be subject to the tests of 7.3
the manufacturer.
as established by written agreement between the manufacturer
9.4 The test report shall be furnished within five working
and the purchaser.
days of shipment of the castings.
9. Certification
10. Keywords
9.1 The manufacturer’s certification shall be furnished to
the purchaser stating that the material was sampled and tested 10.1 austenite; austenitic stainless steel; ferrite; Schoefer
in accordance with the specification (including year date) and Diagram; steel castings
SUPPLEMENTARY REQUIREMENTS
The following supplementary requirements are for use when desired by the purchaser. They shall
not apply unless specified in the order, in which event the specified methods of ferrite content
estimation shall be employed by the manufacturer before shipment of the castings.
S1. Estimation of Ferrite Content by Measurement of made at random in each designated location. For instruments
Magnetic Response having probes making two contacts with the surface being
measured, a “measurement” shall consist of a pair of readings
S1.1 The ferrite content of the heat from which the castings
taken with the probe oriented on perpendicular axes.
are poured shall be estimated from measurements made by
S1.4 Surface Condition:
primary or secondary instruments calibrated in accordance
S1.4.1 The instrument magnet or probe and the surface to be
with the requirements of Practice A 799/A 799M. All measure-
measured shall be dry and cleaned prior to testing to remove
ments shall be made on material after the solution heat
any scale, grease, lint, or dirt that could affect the accuracy of
treatment required by the applicable product specification, or,
measurement.
if any subsequent solution heat treatment is employed, then
S1.4.2 Measurements shall be made more than 0.25 in.
after the final solution heat treatment.
[6.350 mm] from the edge of a surface. When measurements
S1.1.1 Location of measurements—base metal:
are made on a curved surface the radius of curvature must be
S1.1.1.1 Measurements shall be made on the unstrained
greater than 0.375 in. [9.525 mm].
ends of tension test specimens from the same heat as the
S1.5 Acceptance Criteria:
castings represented. Measurements may be made either before
S1.5.1 The average of the ferrite contents estimated from
or after performance of the tension test. If a tension test is not
measurements in each designated location shall be within the
required by the applicable product specification, measurements
limits stated in the order, and not more than two individual
may be made on a specimen cut from a keel block of a design
measurements shall indicate ferrite contents less than or in
in Fig. 3 of Test Methods and Definitions A 370.
excess of these limits.
S1.1.1.2 When further specified, measurements shall be
S1.5.1.1 If ferrite contents are estimated with an instrument
made on the base metal of the castings, or a specified sample
that indicates for each measurement a value between an upper
of castings (not on weld repairs or other weld deposits), in
and a lower limit, mor
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