Overview of Intermetallic Sigma (𝜎) Phase Precipitation in Stainless Steels

Table 2

EDS analysis of 𝛿, 𝜎, and 𝛾 phases at various solid solution temperatures and a fixed cooling rate of 0.1°C s⁻¹ [51].

Element	Fe	Cr	Ni	Mo	Mn	Si
Solution treated at 1020°C and cooled at 0.1°C s^−1
𝜎	61.7±0.5	25.7±0.6	3.46±0.06	6.84±0.08	1.15±0.04	1.15±0.04
𝛿	66.6±0.7	24.1±0.4	3.60±0.06	4.09±0.06	1.15±0.04	0.44±0.02
𝛾	68.0±0.7	20.8±0.4	6.45±0.08	2.42±0.06	1.45±0.04	0.32±0.02
Solution treated at 1080°C and cooled at 0.1°C s^−1
𝜎	62.7±0.5	25.2±0.6	3.92±0.06	5.90±0.08	1.14±0.04	1.13±0.04
𝛿	66.7±0.7	24.0±0.4	3.68±0.06	4.05±0.06	1.15±0.04	0.43±0.02
𝛾	68.3±0.7	20.9±0.4	6.39±0.08	2.45±0.06	1.44±0.04	0.33±0.02
Solution treated at 1200°C and cooled at 0.1°C s^−1
𝛿	67.0±0.7	23.6±0.4	3.83±0.08	3.96±0.06	1.16±0.04	0.41±0.02
𝛾	68.2±0.7	21.3±0.4	6.25±0.08	2.54±0.06	1.33±0.04	0.35±0.02