Table 2.1.2.1.3: Values of Room Temperature Plane-Strain Fracture Toughness of Steel Alloys

MIL-HDBK-5J, Metallic Materials and Elements for Aerospace Vehicle Structures

Last Updated 29 Oct 2026

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Alloy	Heat Treat Condition	Product Form	Orien- tation^b	Yield Strength Range, ksi	Product Thickness Range, inches	Number of Sources	Sample Size	Specimen Thickness Range, inches	K₁, ksi √in.
Alloy	Heat Treat Condition	Product Form	Orien- tation^b	Yield Strength Range, ksi	Product Thickness Range, inches	Number of Sources	Sample Size	Specimen Thickness Range, inches	Max.	Avg.	Min.	Coefficient of Variation
AerMet 100	Anneal, HT to 280ksi	Bar	L-R	236-281	2.75-10	1	183		146	121	100	7.9
AerMet 100	Anneal, HT to 280ksi	Bar	C-R	223-273	2.75-10	1	156		137	112	90	8.5
AerMet 100	Anneal, HT to 290ksi	Bar	L-R	251-265	3-10	1	29		110	99	88	6.5
AerMet 100	Anneal, HT to 290ksi	Bar	C-R	250-268	3-10	1	24		101	88	73	9.7
Custom 465	H950	Bar	L-R^c	229-249	3-12	1	40	1-1.5	104	89	76	7.4
Custom 465	H950	Bar	R-L^c	231-246	3-12	1	40	1-1.5		82	73	6.4
Custom 465	H1000	Bar	L-R^c	212-227	3-12	1	40	1-1.5	131	120	108	5.2
Custom 465	H1000	Bar	R-L^c	212-225	3-12	1	40	1-1.5	118	109	100	3.7
D6AC	1650°F, Aus-Bay Quench 975°F, SQ 375°F, 1000°F 2+2	Plate	L-T	217	1.5	1	19	0.6	88	62	40	22.5
D6AC	1650°F, Aus-Bay Quench 975°F, SQ 400°F, 1000°F 2+2	Plate	L-T	217	0.8	1	103	0.6-0.8	92	64	44	18.9
D6AC	1650°F, Aus-Bay Quench 975°F, SQ 400°F, 1000°F 2+2	Forging	L-T	214	0.8-1.5	1	53	0.6-0.8	96	66	39	18.6
D6AC	1700°F, Aus-Bay Quench 975°F, OQ 140°F, 1000°F 2+2	Plate	L-T	217	0.8-1.5	1	30	0.6-0.8	101	92	64	8.9
D6AC	1700°F, Aus-Bay Quench 975°F, OQ 140°F, 1000°F 2+2	Forging	L-T	214	0.8-1.5	1	34	0.7	109	95	81	6.7
9Ni-4Co-.20C	Quench and Temper	Hand Forging	L-T	185-192	3.0	2	27	1.0-2.0	147	129	117	8.3
9Ni-4Co-.20C	1650°F, 1-2 Hr, AC, 1525°F, 1-2 Hr, OQ, -100°F, Temp	Forging	L-T	186-192	3.0-4.0	3	17	1.5-2.0	147	134	120	8.5
PH13-8Mo	H1000	Forging	L-T	205-212	4.0-8.0	3	12	0.7-2.0	104	90	49	21.5

MIL-HDBK-5J

Table 2.1.2.1.3: Values of Room Temperature Plane-Strain Fracture Toughness of Steel Alloys

MIL-HDBK-5J, Metallic Materials and Elements for Aerospace Vehicle Structures

Last Updated 29 Oct 2026

Hover any section to copy its link or text, ask Copilot about it, or bookmark it.

Alloy	Heat Treat Condition	Product Form	Orien- tation^b	Yield Strength Range, ksi	Product Thickness Range, inches	Number of Sources	Sample Size	Specimen Thickness Range, inches	K₁, ksi √in.
Alloy	Heat Treat Condition	Product Form	Orien- tation^b	Yield Strength Range, ksi	Product Thickness Range, inches	Number of Sources	Sample Size	Specimen Thickness Range, inches	Max.	Avg.	Min.	Coefficient of Variation
AerMet 100	Anneal, HT to 280ksi	Bar	L-R	236-281	2.75-10	1	183		146	121	100	7.9
AerMet 100	Anneal, HT to 280ksi	Bar	C-R	223-273	2.75-10	1	156		137	112	90	8.5
AerMet 100	Anneal, HT to 290ksi	Bar	L-R	251-265	3-10	1	29		110	99	88	6.5
AerMet 100	Anneal, HT to 290ksi	Bar	C-R	250-268	3-10	1	24		101	88	73	9.7
Custom 465	H950	Bar	L-R^c	229-249	3-12	1	40	1-1.5	104	89	76	7.4
Custom 465	H950	Bar	R-L^c	231-246	3-12	1	40	1-1.5		82	73	6.4
Custom 465	H1000	Bar	L-R^c	212-227	3-12	1	40	1-1.5	131	120	108	5.2
Custom 465	H1000	Bar	R-L^c	212-225	3-12	1	40	1-1.5	118	109	100	3.7
D6AC	1650°F, Aus-Bay Quench 975°F, SQ 375°F, 1000°F 2+2	Plate	L-T	217	1.5	1	19	0.6	88	62	40	22.5
D6AC	1650°F, Aus-Bay Quench 975°F, SQ 400°F, 1000°F 2+2	Plate	L-T	217	0.8	1	103	0.6-0.8	92	64	44	18.9
D6AC	1650°F, Aus-Bay Quench 975°F, SQ 400°F, 1000°F 2+2	Forging	L-T	214	0.8-1.5	1	53	0.6-0.8	96	66	39	18.6
D6AC	1700°F, Aus-Bay Quench 975°F, OQ 140°F, 1000°F 2+2	Plate	L-T	217	0.8-1.5	1	30	0.6-0.8	101	92	64	8.9
D6AC	1700°F, Aus-Bay Quench 975°F, OQ 140°F, 1000°F 2+2	Forging	L-T	214	0.8-1.5	1	34	0.7	109	95	81	6.7
9Ni-4Co-.20C	Quench and Temper	Hand Forging	L-T	185-192	3.0	2	27	1.0-2.0	147	129	117	8.3
9Ni-4Co-.20C	1650°F, 1-2 Hr, AC, 1525°F, 1-2 Hr, OQ, -100°F, Temp	Forging	L-T	186-192	3.0-4.0	3	17	1.5-2.0	147	134	120	8.5
PH13-8Mo	H1000	Forging	L-T	205-212	4.0-8.0	3	12	0.7-2.0	104	90	49	21.5