The intergranular corrosion behavior of the low-chromium ferritic stainless steel without Cr-carbide precipitation was investigated by the methods of qualitative and quantitative corrosion testing and microstructural analysis. The intergranular corrosion susceptibility of the aged stainless steels can be attributed to the Cr-depleted zone formation induced by Cr-C co-segregation to grain boundaries before Cr-carbide nucleation. The change of intergranular corrosion morphology after aging at 450 °C from discontinuous (aged for 2 h) to semi-continuous (aged for 20 h) and to continuous (aged for 200 h) is discussed in detail.