MTD slider inspection 11

Since Barkhausen described the magnetic noise associated with the magnetization of ferromagnetic material by a time varying electric current in his paper of 1919 there has been the prospect of using this phenomenon for Non-Destructive Testing and Evaluation. A major problem for many years was in isolating the Barkhausen signals from other electromagnetic effects occurring at the same time. The advent of modern electronic instrumentation has resolved this problem to such an extent that it is now possible to carry out a growing number of inspections to assess the fitness for purpose of ferromagnetic components and materials. This course is designed to prepare students for examinations based on the scheme set out in BS EN ISO 4179 to demonstrate their competence to Level 2.

The course covers but is not limited to:

Alloy Metallurgy
Atomic structure, Bonding, Crystal structure
Solid solutions, Phases
Solidification and Crystal Growth
Lattices, Vacancies

Carbon and Alloy steels
The Iron Carbon Diagram
Responses to Heat Treatment
Hardening, The Martensitic Transformation

Stress and Strain
Young’s Modulus, Hooke’s Law
Elastic, Plastic behaviour, Fracture

Magnetization and Magnetic Fields
Permeability, Susceptibility
Ampere’s Law, Biot-Savart Law
Magnetic Domains, Domain walls
Reversible and Irreversible Domain wall processes
Pinning, The effect of vacancies, impurities, precipitates, phases

Magnetic Barkhausen Noise, Related Phenomena, and Applications
Forces acting on domain walls, Influences on domain wall energy and movement
Hysteresis loops
Barkhausen Jumps
Detection of Elastic and Plastic Strain
Over-tempered and Under-tempered Martensite
Grain size, Carbide precipitates, pearlite colony size, Carbon content
Magnetic Acoustic Emission

Advantages and Disadvantages of the Barkhausen Noise Method

Lunches, refreshments, and a complete set of course notes will be provided during the course.