Magnetic properties of an AISI 420 martensitic stainless steel

The magnetic properties (coercive force, saturation and residual magnetization, and Curie temperature) of an AISI 420 steel were measured for different heat treatment conditions (quenching and tempering). The results show that the material is magnetically softer in the annealed condition and after oil quenching an increase of coercive force (H-M(c)) and residual induction (B-r) and a decrease of saturation magnetization (sigma (s)) are observed. Tempering in the 300-500 degreesC range promotes a further increase of H-M(c) and B-r values. Tempering in the 500-650 degreesC range promotes an increase of sigma (s) and a magnetic softening. The magnetization vs. temperature curves of quenched samples showed a pronounced increase of magnetization before reaching the Curie point. The results are discussed taking the knowledge of the physical metallurgy of the martensitic stainless steels into account. (C) 2000 Elsevier Science B.V. All rights reserved.