A Dislocation-Based Theory for the Deformation Hardening Behavior of DP Steels: Impact of Martensite Content and Ferrite Grain Size

Table 5

Results from the fitting procedure, compilation of parameter values. 𝑓_𝑚 = volume fraction of martensite, 𝑓₁: initial active volume fraction of ferrite, 𝑟: rate constant, 𝑠₁ = start value of dislocation mean free path, 𝑠₀ = final value of dislocation mean free path, 𝑘: rate constant, 𝜎_𝑖0: friction stress, 𝜎_𝑛: flow stress at necking, 𝜀_𝑛: strain at necking, 𝑒: mean error (discrepancy between model and experimental values). Mean values from double samples shown in Table 4.

	𝑓𝑚	𝑓1	r	𝑠1 (m)	𝑠0 (m)	k	𝜎𝑖0 [MPa]	𝜎𝑛 [MPa]	𝜀𝑛	e [MPa]
DP500	0.13	0.244	27.5	8.2𝐸−07	6.2𝐸−07	102	219	632	0.138	0.076
DP600	0.18	0.127	25.1	5.9𝐸−07	4.5𝐸−07	269	228	720	0.116	0.085
DP800	0.25	0.083	23.1	5.5𝐸−07	3.5𝐸−07	226	331	900	0.097	0.068
DP980	0.48	0.075	27.4	9.1𝐸−07	2.6𝐸−07	732	475	1162	0.086	0.105