STEEL GRADING BY MICROMAGNETIC TECHNIQUES Steel Grading by Magnetic Method

Abstract Tube samples of six different steel qualities namely ST 35, ST 45, ST 52, ST 55, ST 65 (DIN standards 2391 T2) and 10 CrMo 9 10 (DIN standard 17175) and four different kinds of thermomechanical treatments (eg. cold worked; cold worked and annealed; cold worked, annealed and cold drawn; the one without proper cold working for ST 65 and 10 CrMo 9 10 only) were sorted by the micromagnetic methods on the basis of the different magnetic properties of these materials. Magnetic Barkhausen noise (MBN), the coercivity (H∞) corresponding to maximum MBN, distortion factor (K) and the coercivity (H∞) derived from the upper harmonics of the tangential field strength were measured and estimated for each tube sample using a laboratory set-up. Attempts have been made to explain the difference in the magnetic properties of these materials on the basis of compositions and thermomechanical treatments.