Abstract
The effect of intermediate annealing treatment on the micro-hardness and corrosion resistance for Nickel – Chromium (3.2%Ni-1.57%Cr) alloy steel was carried out in this investigation, specimens from this steel were prepared and carburized, hardened and tempered, and intermediate annealing process was added at different temperature (750,770, and7900C)to achieve a structure of ferrite (α-Fe) and austenite(γ-Fe) phases by heating and then dual-phase structure by quenching in oil and at different times (45, 60, and75 min) to uniform the distribution of carbon in this alloy steel before hardening process.
The loss of weight method was used as a function to measure the corrosion resistance for Nickel - Chromium alloy steel after embedded in (3.5%NaCl ) solution as an aggressive media for different holding times (2, 4,5,8 and 10 Days) .
It was found that was an increase or decrease in the hardness depending on the temperature of the intermediate annealing treatment and its holding time.
The study also showed an increase in the corrosion resistance mainly due to the temperature of the intermediate annealing treatment and decrease when the holding time increase .
The experimental results showed that the best micro-hardness value was found at(7500C) intermediate annealing temperature for (58min) holding time and the best corrosion resistance was a chivied at (7900C) with( 45 min ) holding time and (2Day) embedded time .
