Application of Response Surface Methodology for Modeling of Postweld Heat Treatment Process in a Pressure Vessel Steel ASTM A516 Grade 70

Table 5

Estimated regression coefficients for tensile strength.

Term	Coef.	SE coef.
Constant	535.400	1.064	503.171	0.000
PWHT time	−12.474	1.346	−9.268	0.000
PWHT temp.	−1.439	1.346	−1.069	0.294
PWHT time PWHT time	−0.463	2.019	−0.229	0.820
PWHT temp. PWHT temp.	−18.300	2.019	−9.064	0.000
PWHT time PWHT temp.	−29.500	4.662	−6.327	0.000

= 4.037795.134; = 87.90%; (adj.) = 85.89%.