Optimization of Deformation Behaviors during Continuous Forming Extrusion of C18150 Copper Alloy through Response Surface Methodology

Table 8

Estimated regression coefficients for effective stress (test of significance for extrusion effective stress for C18150).

Term	Coef	SE coef	T
Constant	11621.2	105.795	109.847	0.000
x1	−67.2	1.568	−42.886	0.000
x2	0.6	0.068	8.818	0.000
x3	−1.4	0.066	−20.474	0.000
x4	−21486.7	202.635	−106.036	0.000
	1.7	0.017	99.108	0.000
	−0.0	0.000	−64.695	0.000
	−0.0	0.000	−43.589	0.000
	8400.0	108.972	77.084	0.000
	−0.0	0.001	−0.795	0.442
	−0.1	0.001	−161.328	0.000
	112.5	1.573	71.525	0.000
	−0.0	0.000	−95.366	0.000
	3.5	0.063	55.630	0.000
	6.0	0.063	95.366	0.000