Table 3.

Material parameters with two and three back-stress terms determined by varying all parameters simultaneously during optimization.

	2 Back-Stress Terms			3 Back-Stress Terms
Parameter	Min	Mid	Max	Min	Mid	Max
C1 (MPa)	64,193	87,366	148,784	68,783	107,437	110,187
γ1	138	171	434	229	253	336
C2 (MPa)	3722	3616	4227	3660	3628	3567
γ2	0	0	0	0	0	0
C3 (MPa)	--	--	--	34,543	29,012	14,582
γ3	--	--	--	165	355	75
Q (MPa)	−252	−251	−55	−276	−275	−247
b	3.31	8.39	7.87	7.97	11.09	9.54
${\dot{\epsilon }}_0$ (s−1)	1.54 × 10−6	9.46 × 10−7	2.87 × 10−7	1.86 × 10−6	8.39 × 10−6	7.67 × 10−6
n	10	11	9.8	8	6.5	7.7
m	−0.96	−0.92	−0.67	−0.58	−0.82	−0.91
NMSE	9.73 × 10−5	1.10 × 10−4	1.27 × 10−4	9.73 × 10−5	9.57 × 10−5	9.88 × 10−5