Fracture Behavior of Ion-Nitrided AISI 4140 Steel in accordance with Variable Applied Current Density

Table 1

Statistical analysis of the indentation fracture toughness (K_Ic) of nitrided AISI 4140 steel as a function of the test load, using the equation of Shetty et al.

Specimen	F, N	c/a	KIc, MPa m^1/2
			Average	Min.	Max.
Sample A	29.42	1.06–1.20	8.89	6.86	11.87
	98	1.09–1.16	10.47	9.03	11.79
	294	1.13–1.22	10.62	8.77	11.55
	490	1.12–1.29	11.30	8.25	13.04
Sample B	29.42	-	-	-	-
	98	-	-	-	-
	294	1.12–1.14	13.12	11.72	13.69
	490	1.09–1.10	16.50	15.86	16.84
Sample C	29.42	-	-	-	-
	98	-	-	-	-
	294	1.18–1.23	10.49	9.75	11.41
	490	1.17–1.18	12.33	12.17	12.46