AMS 6415.pdf

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AEROSPACE

MATERIAL SPECIFICATION

AMS6415™ REV. V

Issued 1940-01 Revised 2022-11

Superseding AMS6415U

Steel, Bars, Forgings, Mechanical Tubing, and Forging Stock 0.80Cr - 1.8Ni - 0.25Mo (0.38 - 0.43C) (SAE 4340)

(Composition similar to UNS G43406)

RATIONALE

AMS6415V is the result of a Five-Year Review and update of the specification. The revision updates the Title to match the scope, prohibits unauthorized exceptions (3.6, 4.4.5, 5.2.1.1, 8.7), updates composition testing and reporting (3.1, 3.1.2), updates heat treatment specification (3.2.2), modifies Jominy requirements (3.3.3), updates macrostructure (Table 2, 3.3.1, 8.8), updates decarburization test methods (3.3.4.5), acknowledges changes to AMS2301 (4.2.1, 4.4.4), adds note on stock removal (8.5), and allows prior revisions (8.6).

1. SCOPE

1.1 Form

This specification covers an aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock.

1.2 Application

These products have been used typically for parts, 3.5 inches (89 mm) and under in nominal thickness at time of heat treatment, requiring a through-hardening steel capable of developing a minimum hardness of 40 HRC when properly hardened and tempered and also for parts of greater thickness, but requiring proportionately lower hardness. Usage is not limited to such applications.

1.2.1 Certain design and processing procedures may cause these products to become susceptible to stress-corrosion cracking after heat treatment; ARP1110 recommends practices to minimize such conditions.

2. APPLICABLE DOCUMENTS

The issue of the following documents in effect on the date of the purchase order forms a part of this specification to the extent specified herein. The supplier may work to a subsequent revision of a document unless a specific document issue is specified. When the referenced document has been cancelled and no superseding document has been specified, the last published issue of that document shall apply.

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2.1 SAE Publications

Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or +1 724-776-4970 (outside USA), www.sae.org.

AMS2251 Tolerances, Low-Alloy Steel Bars

AMS2253 Tolerances, Carbon and Alloy Steel Tubing

AMS2259 Chemical Check Analysis Limits, Wrought Low-Alloy and Carbon Steels

AMS2301 Steel Cleanliness, Aircraft Quality, Magnetic Particle Inspection Procedure

AMS2370 Quality Assurance Sampling and Testing, Carbon and Low-Alloy Steel Wrought Products and Forging Stock

AMS2372 Quality Assurance Sampling and Testing, Carbon and Low-Alloy Steel Forgings

AMS2761 Heat Treatment of Steel Raw Materials

AMS2806 Identification Bars, Wire, Mechanical Tubing, and Extrusions, Carbon and Alloy Steels and Corrosion and Heat-Resistant Steels and Alloys

AMS2808 Identification, Forgings

ARP1110 Minimizing Stress Corrosion Cracking in Wrought Forms of Steels and Corrosion Resistant Steels and Alloys

AS1182 Standard Stock Removal Allowance, Aircraft-Quality and Premium Aircraft-Quality Steel Bars and Mechanical Tubing

AS7766 Terms Used in Aerospace Metals Specifications

2.2 ASTM Publications

Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org.

ASTM A255 Determining Hardenability of Steel

ASTM A370 Mechanical Testing of Steel Products

ASTM A751 Chemical Analysis of Steel Products

ASTM E112 Determining Average Grain Size

ASTM E140 Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness

ASTM E381 Macroetch Testing Steel, Bars, Billets, Blooms, and Forgings

ASTM E1077 Estimating the Depth of Decarburization of Steel Specimens

2.3 Definitions

Terms used in AMS are defined in AS7766.

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3. TECHNICAL REQUIREMENTS

3.1 Composition

Shall conform to the percentages by weight shown in Table 1, determined in accordance with ASTM A751 or by other analytical methods acceptable to purchaser.

Table 1 - Composition

Element Min Max Carbon 0.38 0.43 Manganese 0.65 0.85 Silicon 0.15 0.35 Phosphorus -- 0.025 Sulfur -- 0.025 Chromium 0.70 0.90 Nickel 1.65 2.00 Molybdenum 0.20 0.30 Copper -- 0.35

3.1.1 Aluminum, vanadium, and columbium (niobium) are optional grain refining elements and need not be determined or reported unless used to satisfy the average grain size requirements of 3.3.2.2.

3.1.2 Producer may test for any element not listed in Table 1 and include this analysis in the report of 4.4. Reporting of any element not listed in the composition table is not a basis for rejection, unless limits of acceptability are specified by the purchaser.

3.1.3 Check Analysis

Composition variations shall meet the applicable requirements of AMS2259.

3.2 Condition

The product shall be supplied in the following condition; hardness and tensile strength shall be determined in accordance with ASTM A370:

3.2.1 Bars

Bar shall not be cut from plate (also see 4.4.2).

3.2.1.1 Bars 0.500 Inch and Under in Nominal Diameter, or Least Distance Between Parallel Sides

Cold finished having tensile strength not higher than 125 ksi or hardness not higher than 27 HRC, or equivalent (see 8.2).

3.2.1.2 Bars Over 0.500 Inch in Nominal Diameter, or Least Distance Between Parallel Sides

Hot finished and annealed, unless otherwise ordered, having hardness not higher than 235 HBW, or equivalent (see 8.2).

Bars ordered cold finished may have hardness as high as 255 HBW, or equivalent (see 8.2).

3.2.2 Forgings

Normalized and tempered in accordance with AMS2761 to a hardness not higher than 269 HBW, or equivalent, unless otherwise ordered (see 8.2).

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3.2.3 Mechanical Tubing

Cold finished, unless otherwise ordered, having hardness not higher than 25 HRC, or equivalent (see 8.2). Tubing ordered hot finished and annealed shall have hardness not higher than 99 HRB, or equivalent (see 8.2).

3.2.4 Forging Stock

As ordered by the forging manufacturer.

3.3 Properties

The product shall conform to the following requirements; hardness testing shall be performed in accordance with

ASTM A370:

3.3.1 Macrostructure

Visual examination of transverse full cross-sections from bars, billets, tube rounds (solid, not hollow), and forging stock, etched in hot hydrochloric acid in accordance with ASTM E381, shall show no pipe or cracks. Porosity, segregation, inclusions, and other imperfections shall be no worse than the macrographs of ASTM E381 shown in Table 2.

Table 2 - Macrostructure limits

Cross-Sectional Area Square Inches

Cross-Sectional Area Square Centimeters Macrographs

Up to 36, incl Up to 232, incl S2 - R1 - C2 Over 36 to 100, incl Over 232 to 645. incl S2 - R2 – C2 Over 100 to 133. incl Over 645 to 858, incl S2 - R2 - C3 Over 133 Over 858 Note 1

Note 1: Limits for larger sizes shall be agreed upon by purchaser and producer.

3.3.1.1 Macrostructure examination is not required for bored/hollow forgings (including ring forgings) and mechanical tubing that is produced directly from ingots or large blooms unless otherwise agreed upon by purchaser and producer (see 8.8).

3.3.1.2 If mechanical tubing is produced directly from ingots or large blooms, transverse sections may be taken from the tubing. Macroetch standards for such tubes shall be as agreed upon by purchaser and producer (see 8.8).

3.3.2 Average Grain Size of Bars, Forgings, and Tubing

Average grain size shall be determined by either 3.3.2.1 or 3.3.2.2.

3.3.2.1 Shall be ASTM No. 5 or finer, determined in accordance with ASTM E112.

3.3.2.2 The product of a heat shall be considered to have an ASTM No. 5 or finer austenitic grain size if one or more of the following are determined by heat analysis (see 8.4):

3.3.2.2.1 A total aluminum content of 0.020 to 0.050%.

3.3.2.2.2 An acid soluble aluminum content of 0.015 to 0.050%.

3.3.2.2.3 A vanadium content of 0.02 to 0.08%.

3.3.2.2.4 A columbium (niobium) content of 0.02 to 0.05%.

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3.3.3 Hardenability of Each Heat

Shall be J 12/16 inch (19 mm) = 53 HRC minimum and J 20/16 inch (32 mm) = 50 HRC minimum, determined on the standard end-quench test specimen in accordance with ASTM A255 except that the steel shall be normalized at 1600 °F ± 10 °F (871 °C ± 6 °C) and the test specimen austenitized at 1550 °F ± 10 °F (843 °C ± 6 °C). Cast specimens do not need to be normalized.

3.3.4 Decarburization

3.3.4.1 Bars and tubing ordered ground, turned, or polished shall be free from decarburization on the ground, turned, or polished surfaces. Decarburization on tubing ID shall not exceed the maximum depth specified in Table 4.

3.3.4.2 Allowable decarburization of bars, billets, and tube rounds ordered for redrawing or forging or to specified microstructural requirements shall be as agreed upon by purchaser and producer.

3.3.4.3 Decarburization of bars, for which 3.3.4.1 or 3.3.4.2 are not applicable, shall not exceed the values shown in Table 3.

Table 3A - Maximum total depth of decarburization, inch/pound units

Nominal Diameter or Distance Between Parallel Sides

Inches

Total Depth of Decarburization

Inches Up to 0.375, incl 0.010 Over 0.375 to 0.500, incl 0.012 Over 0.500 to 0.625, incl 0.014 Over 0.625 to 1.000, incl 0.017 Over 1.000 to 1.500, incl 0.020 Over 1.500 to 2.000, incl 0.025 Over 2.000 to 2.500, incl 0.030 Over 2.500 to 3.000, incl 0.035 Over 3.000 to 4.000, incl 0.045

Table 3B - Maximum total depth of decarburization, SI units

Nominal Diameter or Distance Between Parallel Sides

Millimeters

Total Depth of Decarburization

Millimeters Up to 9.50, incl 0.25

Over 9.50 to 12.50, incl 0.30 Over 12.50 to 15.65, incl 0.36 Over 15.65 to 25.00, incl 0.43 Over 25.00 to 37.50, incl 0.51 Over 37.50 to 50.00, incl 0.64 Over 50.00 to 62.50, incl 0.76 Over 62.50 to 75.00, incl 0.89 Over 75.00 to 100.00, incl 1.14

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3.3.4.4 Decarburization of tubing, for which 3.3.4.1 or 3.3.4.2 are not applicable, shall not exceed the values shown in

Table 4.

Table 4A - Maximum total depth of decarburization, inch/pound units

Nominal Wall Thickness Inches

Total Depth

ID

Inches

Total Depth

OD

Inches Up to 0.109, incl 0.008 0.015 Over 0.109 to 0.203, incl 0.010 0.020 Over 0.203 to 0.400, incl 0.012 0.025 Over 0.400 to 0.600, incl 0.015 0.030 Over 0.600 to 1.000, incl 0.017 0.035 Over 1.000 0.020 0.040

Table 4B - Maximum total depth of decarburization, SI units

Nominal Wall Thickness Millimeters

Total Depth

ID

Millimeters

Total Depth

OD

Millimeters Up to 2.75, incl 0.20 0.38 Over 2.75 to 5.00, incl 0.25 0.51 Over 5.00 to 10.00, incl 0.30 0.64 Over 10.00 to 15.00, incl 0.35 0.76 Over 15.00 to 25.00, incl 0.40 0.89 Over 25.00 0.50 1.02

3.3.4.5 Decarburization shall be evaluated by one of the two methods of 3.3.4.5.1 or 3.3.4.5.2.

3.3.4.5.1 Metallographic (Microscopic) Method

A cross section taken perpendicular to the surface shall be prepared in accordance with ASTM E1077, etched, and examined metallographically at a magnification not to exceed 200X. The product shall not show a layer of complete (ferrite) or partial decarburization exceeding the limits of Table 3 or 4.

3.3.4.5.2 Hardness Traverse (Microindentation) Method

The total depth of decarburization shall be determined by a traverse method using microindentation hardness testing in accordance with ASTM E1077. Samples shall be hardened, but untempered, protected during heat treatment to prevent changes in surface carbon content. Measurements shall be far enough away from any adjacent surface to be uninfluenced by any decarburization on the adjacent surface. Acceptance shall be as listed in Table 3 or 4.

3.3.4.6 When determining the depth of decarburization, it is permissible to disregard local areas provided the decarburization of such areas does not exceed the above limits by more than 0.005 inch (0.13 mm) and the width is 0.065 inch (1.65 mm) or less.

3.3.4.7 In case of dispute, the total depth of decarburization determined using the microindentation hardness traverse method shall govern.

3.4 Quality

The product, as received by purchaser, shall be uniform in quality and condition, sound, and free from foreign materials and from imperfections detrimental to usage of the product.

3.4.1 Steel shall be aircraft-quality conforming to AMS2301, except specimens containing nonmetallic inclusions over 1 inch (25 mm) in length, shall be subject to rejection.

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3.4.2 Bars and mechanical tubing shall be free from seams, laps, tears, and cracks after removal of the standard stock removal allowance in accordance with AS1182.

3.4.3 Grain flow of die forgings, except in areas that contain flash-line end grain, shall follow the general contour of the forgings showing no evidence of reentrant grain flow.

3.5 Tolerances

3.5.1 Bars

In accordance with AMS2251.

3.5.2 Mechanical Tubing

In accordance with AMS2253.

3.6 Exceptions

Any exceptions shall be authorized by the purchaser and reported as in 4.4.5.

4. QUALITY ASSURANCE PROVISIONS

4.1 Responsibility for Inspection

The producer of the product shall supply all samples for producer’s tests and shall be responsible for the performance of all required tests. Purchaser reserves the right to sample and to perform any confirmatory testing deemed necessary to ensure that the product conforms to specified requirements.

4.2 Classification of Tests

4.2.1 Acceptance Tests

Composition (3.1), condition (3.2), macrostructure (3.3.1), average grain size (3.3.2), hardenability (3.3.3), decarburization (3.3.4), frequency-severity cleanliness rating (3.4.1), and tolerances (3.5) are acceptance tests and shall be performed on each heat or lot as applicable. If grain refining elements (3.3.2.2) are not present, the ASTM E112 grain size test (3.3.2.1) shall be conducted on each lot. If process qualification in accordance with AMS2301 has been met, the frequency-severity rating shall be conducted on a periodic basis as defined in AMS2301.

4.2.2 Periodic Tests

If grain refining elements (3.3.2.2) are present, the ASTM E112 grain size test (3.3.2.1) shall be conducted on a periodic basis and shall be performed at a frequency selected by the producer (not to exceed 1 year) unless frequency of testing is specified by purchaser. Grain flow of die forgings (3.4.3) is a periodic test and shall be performed at a frequency selected by the producer unless frequency of testing is specified by purchaser.

4.3 Sampling and Testing

4.3.1 Bars, Mechanical Tubing and Forging Stock

In accordance with AMS2370.

4.3.2 Forgings

In accordance with AMS2372.

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4.4 Reports

4.4.1 The producer of bars, forgings, and tubing shall furnish with each shipment a report showing the producer identity, country where the metal was melted (e.g., final melt in the case of metal processed by multiple melting operations), the results of tests for composition, macrostructure, hardenability, and frequency-severity cleanliness rating of each heat (see 4.4.4) and condition and average grain size, if measured, of each lot, and stating that the product conforms to the other technical requirements. This report shall include the purchase order number, heat and lot numbers, AMS6415V, product form and size (and/or part number, if applicable), and quantity. If the grain size requirement of

3.3.1.2 is met by the aluminum, vanadium and/or columbium (niobium) content, the aluminum, vanadium and/or columbium (niobium) content shall be reported and a statement that the chemistry satisfies the grain size requirement shall be included. If forgings are supplied, the size and melt source of stock used to make the forgings shall also be included.

4.4.2 If the ship size/shape is cut from a larger cross section, report the nominal metallurgically worked size (also see 3.2.1).

4.4.3 The producer of forging stock shall furnish with each shipment a report showing the producer identity, country where the metal was melted (e.g., final melt in the case of metal processed by multiple melting operations), the results of tests for composition, macrostructure, hardenability, and frequency-severity cleanliness rating of each heat (see 4.4.4) and the results of any additional property requirements imposed by 8.8. This report shall include the purchase order number, heat number, AMS6415V, size, and quantity.

4.4.4 Reduced Testing

If the producer has qualified for periodic testing for frequency-severity cleanliness rating in accordance with AMS2301, then the frequency severity cleanliness rating is not required to be reported for each shipment. In this circumstance the report shall read “Process qualification in accordance with AMS2301 has been completed.”

4.4.5 When material produced to this specification has exceptions taken to the technical requirements listed in Section 3, the report shall contain a statement "This material is certified as AMS6415V(EXC) because of the following exceptions:" and the specific exceptions shall be listed (also see 5.2.1.1).

4.5 Resampling and Retesting

4.5.1 Bars, Mechanical Tubing, and Forging Stock

In accordance with AMS2370.

4.5.2 Forgings

In accordance with AMS2372.

5. PREPARATION FOR DELIVERY

5.1 Sizes

Except when exact lengths or multiples of exact lengths are ordered, straight bars and tubing will be acceptable in mill lengths of 6 to 20 feet (1.8 to 6.1 m), but not more than 10% of any shipment shall be supplied in lengths shorter than 10 feet (3 m).

5.2 Identification

5.2.1 Bars and Mechanical Tubing

5.2.1.1 In accordance with AMS2806. When technical exceptions are taken (see 4.4.5), the material shall be identified with AMS6415V(EXC).

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5.2.2 Forgings

In accordance with AMS2808.

5.2.3 Forging Stock

As agreed upon by purchaser and producer.

5.3 Protective Treatment

Bars and tubing ordered cold drawn, cold rolled, ground, turned, or polished shall be protected from corrosion prior to shipment.

5.4 Packaging

The product shall be prepared for shipment in accordance with commercial practice and in compliance with applicable rules and regulations pertaining to the handling, packaging, and transportation of the product to ensure carrier acceptance and safe delivery.

6. ACKNOWLEDGMENT

A producer shall include this specification number and its revision letter in all quotations and when acknowledging purchase orders.

7. REJECTIONS

Product not conforming to this specification, or to modifications authorized by purchaser, will be subject to rejection.

8. NOTES

8.1 Revision Indicator

A change bar (l) located in the left margin is for the convenience of the user in locating areas where technical revisions, not editorial changes, have been made to the previous issue of this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical revisions. Change bars and (R) are not used in original publications, nor in documents that contain editorial changes only.

8.2 Hardness conversion tables for metals are presented in ASTM E140.

8.3 Dimensions and properties in inch/pound units and the Fahrenheit temperatures are primary; dimensions and properties in SI units and the Celsius temperatures are shown as the approximate equivalents of the primary units and are presented only for information.

8.4 Grain size

The average grain size resulting from using the appropriate test procedures per ASTM E112 will satisfy an ASTM No. 5 or finer grain size when the elements defined in 3.3.2.2 as grain refiners are present. Other technical societies have adopted the verification of fine grain steel based on chemistry alone. Included are ASTM International (Documents A6, A20, and A29); American Society of Mechanical Engineers (Documents SA6, SA20, and SA29); American Bureau of Shipping; CSA Group (Canada); EuroNorm documents; American Association of State Highway and Transportation Officials.

8.5 Purchasers should consider stock removal requirements of 3.4.2 when selecting the appropriate size and condition including surface finish to specify in ordering information.

8.6 Unless otherwise specified, the material producer shall work to the revision of this specification (AMS6415) in effect on the date of order placement. Unless otherwise specified, material manufactured and certified to the immediately previous revision of this specification (AMS6415) may be procured and used until inventory is depleted.

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8.7 It is the purchaser’s obligation to ensure that product they procure or resell as AMS6415V has any exceptions approved by their subsequent purchaser.

8.8 Purchase documents should specify not less than the following:

AMS6415V

Product form and size (and/or part number, if applicable) of product desired Quantity of product desired If forging stock, specify any additional property requirements beyond those reported in 4.4.3 and provide details of how to obtain the desired samples When macrostructure is required for hollow/bored forgings, rings and mechanical tubing include examination method and acceptance standard

PREPARED BY SAE AMS E CARBON AND LOW ALLOY STEELS COMMITTEE

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3.3.2 Average Grain Size of Bars, Forgings, and Tubing

3.6 Exceptions