1

Addressing Problems with Revealing

Prior Austenite Grain Boundaries

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Walt Moorhead and Ick KayafasProduct Evaluation Systems, Inc.

Chris BagnallMCS Associates, Inc.

November 17, 2010

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Background

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

“PAGS” INFLUENCED BY:

• Carbon content,

• Thermo-mechanical history,

• Austenitizing temperature/time

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PAGS MEASUREMENT METHODS

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Seven different methods in ASTM E112, Annex A3 for establishing Prior Austenite Grain Size

1. Correlation Procedure2. Carburizing method (Mcquaid-Ehn)3. Mock-Carburizing method4. Hypoeutectoid Steels -two-step method5. Oxidation method6. Full-Hardening (+ tempering) method7. Hypereutectoid Steels -slow cool (cementite) method

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Background (cont.)

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

• No issues with AISI 1045, 1050,

4140, 4340, 4150

• Or are there issues?

• Problems arise when C content

falls below 0.25%C

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Material: AISI 4140/4340

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

4140 Chemistry: 0.4C, 1.0Mn, 1.0Cr, 0.2Mo

As-Received AISI 4140; Picral/Nital etch

Lollipop Section

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Material: AISI 4140/4340

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

4340 Chemistry: 0.4C, 0.8Mn, 0.9Cr, 2.0Ni, 0.3Mo

As-Received, Nital Etch

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Material: AISI 4140/4340

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

4340 Chemistry: 0.4C, 0.8Mn, 0.9Cr, 2.0Ni, 0.3Mo

As-Received, Stepan-Nacconol Etch

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Material: AISI 4150, (1045)

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

• Heat treat per ASTM 3.2.1.3

• Hold above A3 /1 hour (non-carburizing)

• W/Q to form martensite

• Mount, polish, etch with selected reagent

Chemistry: 0.5C, 1.0Mn, 1.0Cr, 0.2Mo

Mock-Carburizing Procedure

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Material: AISI 4150

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Chemistry: 0.5C, 1.0Mn, 1.0Cr, 0.2MoMock-Carburizing Procedure

1,470°F/1h/Q.

Highly unstable boundaries; considered to be sub-grains and not PAGBs

Etch: Picric + Stepan-Nacconol

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Material: AISI 4140/4340

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

McQuaid-Ehn Test:

• Packed in active carbon

• 1700°F/8 hours + A/C

• Mount, polish, etch with selected reagent

4140 Chemistry: 0.4C, 1.0Mn, 1.0Cr, 0.2Mo4340 Chemistry: 0.4C, 0.8Mn, 0.9Cr, 2.0Ni, 0.3Mo

Carburizing Procedure

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Material: AISI 4340

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

4340 Chemistry: 0.4C, 0.8Mn, 0.9Cr, 2.0Ni, 0.3MoCarburizing Procedure Oxidizing Procedure

1575°F/1h/WQ. ASTM 8

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Material: “4340” Bar Product

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Chemistry: 0.4C, 0.45Mn, 0.3Si, 1.8Cr, 4.0Ni, 0.45Mo, 0.03V

As Received

Stepan-Nacconol Etch. ASTM 7

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LOW CARBON STEELS

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

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Material: ASTM A336 (Alloy F22)

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Chemistry (MAX): 0.15C 0.6Mn 0.5Si 2.6Cr 1.13MoMcQuaid-Ehn Test: 1700F/8h

25X 100X

Etch: Picric Acid + Stepan-Nacconol

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Material: ASTM A336 (Alloy F22)

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Chemistry (MAX): 0.15C 0.6Mn 0.5Si 2.6Cr 1.13MoMcQuaid-Ehn Test: 1700F/8h

200X 500X

Etch: Picric Acid + Stepan-Nacconol

ASTM 8

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Material: ASTM A336 (Alloy F22)

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Chemistry (MAX): 0.15C 0.6Mn 0.5Si 2.6Cr 1.13MoMcQuaid-Ehn Test: 1700F/8h

2kX 20kXElt. Line At. % Wt. %Si Ka 8.6 4.5Cr Ka 0.6 0.6Fe Ka 90.8 94.9

#30No carbide at gbs

SEI SEI

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Material: ASTM A336 (Alloy F22)

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Chemistry (MAX): 0.15C 0.6Mn 0.5Si 2.6Cr 1.13MoOxidation v Carburization

Sample cut from a casting runner

Small (sub?) grains ASTM 8 1/2

Carburized10 microns removed

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Material: ASTM A336 (Alloy F22)

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Chemistry (MAX): 0.15C 0.6Mn 0.5Si 2.6Cr 1.13MoMcQuaid-Ehn Test: 1700F/8h

SEI SEI

Problems:

• Depth of carburization << 0.050”

• Si content very high at gbs

• Carbon will “diffuse” away from, or be repulsed by high-Si locations

• Are we measuring grains-or sub-grains?

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Material: ASTM A336 (Alloy F22)

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Chemistry (MAX): 0.15C 0.6Mn 0.5Si 2.6Cr 1.13MoOxidation v Carburization

Sample Cut from a Casting Runner

As Oxidized Carburized10 microns removed

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Material: ASTM A336 (Alloy F22)

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Low Carbon Steel

Problems:

• Time required for evaluation

• Uncertainty of results

• Lollipop V Runner

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OTHER PAGS MEASUREMENT METHODS

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

• Fracture Grain Size MethodShepherd Standard

• Hydrogen Embrittlement Method

• Patented “Burning” Method

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OTHER PAGS MEASUREMENT METHODS

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

• Fracture Grain Size Method:Shepherd Standard

23

OTHER PAGS MEASUREMENT METHODS

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

• Fracture Grain Size Method:Shepherd Standard

25X ASTM 9ASTM 4

24

OTHER PAGS MEASUREMENT METHODS

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

• Fracture Grain Size MethodShepherd Standard

• Hydrogen Embrittlement Method

25

OTHER PAGS MEASUREMENT METHODS

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

•Hydrogen Embrittlement Method

Machined from Cast Slug and H charged

26

OTHER PAGS MEASUREMENT METHODS

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

•Hydrogen Embrittlement Method

Machined from Cast Slug and H-charged

27

OTHER PAGS MEASUREMENT METHODS

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

•Hydrogen Embrittlement Method

Machined from Cast Slug and H-charged

28

OTHER PAGS MEASUREMENT METHODS

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

• Fracture Grain Size MethodShepherd Standard

• Hydrogen Embrittlement Method

• Patented “Burning” Method

29

Material: AISI 1022

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Chemistry: 0.23C, 1.0Mn

Burning Method

• Lollipop sample cut without

using coolant.

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Material: AISI 1022

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Chemistry: 0.23C, 1.0MnLollipop Sample: Burning Method

Only area “safe” for measurement

Etch: Picric Acid + Nital

31

Material: AISI 1022

ASTM Subcommittee E04.08 Workshop:  Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods

Chemistry: 0.23C, 1.0MnBurning Method

Stepan-Nacconol Nital