Effects of Cr Content on the Microstructure and Properties of 26Cr–3.5Mo–2Ni and 29Cr–3.5Mo–2Ni Super Ferritic Stainless Steels

By using scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction, strength and hardness measurements, the microstructure, precipitation, mechanical properties, and corrosion resistance have been investigated for two super ferritic stainless steels, 26Cr–3.5Mo–2Ni and 29Cr–3.5Mo–2Ni, with the aim to consider the effect of Cr content. The results showed that with the addition of Cr content, the recrystallization temperature was increased; the precipitation of Laves and Sigma (σ) phases was promoted and the mechanical properties of super ferritic stainless steel were modified. Furthermore, the pitting corrosion resistance and corrosion resistance to H2SO4 of the two super ferritic stainless steels were improved. In addition, suitable annealing processing is a key factor to maintain integrated performance by optimizing microstructure and removing detrimental precipitation phases.