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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
2
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
3
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
4
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
5
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
6
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
7
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
8
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
9
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
10
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
11
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
12
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
13
LOW CARBON STEELS
ASTM Subcommittee E04.08 Workshop: Grain Size Determination According to ASTM E112, E930, E1181, E1382 and Other Methods
14
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
15
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
16
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
17
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
18
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?
19
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
20
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
21
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
22
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.
30
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