The solution of picric acid and sodium dodecyl benzene sulfonate(SDBS) has been used to corrode the aged turbine rotor steel sample. Through orthoganal test and observation of the microstructure for the aged turbine rotor steel specimen

the optimal test condition has been determined

i.e.a saturated picric acid solution

SDBS 0.005 mol/L

pH 0.2

35 min

and 25 ℃.Results show that the sequence of five affecting factors upon the width of grain boundary is as follows: picric acid concentration

pH value

SDBS concentration

temperature

and time.The microstructure of samples has been measured and analysed by using the Photoshop instrument

the affecting factors upon the Fracture Appearance Transition Temperature(FATT) being determined;a multiple linear regression analysis has been carried out by using SPSS

and the FATT50 prediction model being established.The model has been verified by using two samples

i.e.A2 and A2a

the prediction errors to be in a range of ±20 ℃.