Cu Precipitation in Cu Age-hardening Steel

Cu precipitation behavior in a Cu-bearing steel was investigated. The experimental results indicated that the hardness reach quickly to peak during isothermal aging at 500-550 ℃, and then slow down as the prolongation of aging time.The Cu strengthening effectiveness was depended on strongly the aging temperature. The aging temperature of the hardness peak is about 500 ℃ in the tested Cu age-hardening steel, and at this temperature, fine Cu particles precipitated largely along dislocation line, lath boundaries and in ferrite with the size less than 5 nm, which contributed to strong precipitation strengthening. At the condition of overaging (above 600 ℃), the size of Cu particles happen to coarsen obviously and grow to become into rod-like from spheral in the particle shape, and finally its precipitation strengthening is weakened.