A NOVEL VSM MAGNETOMETER AND ITS APPLICATION TO DETECT INDUCED MAGNETIC ANISOTROPY

István Mészáros

   Nowadays, there is increasing importance of the remaining life time estimation of these engineering structures. In the present paper we summarize some of our results obtained in the field of magnetic testing of creep tested power plant steel. In this work 15Mo3 type ferritic heat resistant steel was investigated. This steel and several similar grades are commonly used in power plants boilers as the material of reheating steam pipelines and pressure vessels. Their typical application temperature is about 500 -550°C. It is commonly accepted that a combined form of mechanical, thermal fatigue and the creep processes causes the long term deteriorat ion of this structural steels. The applied thermal shock fatigue and creep tests can properly model the material degradation due to long term service in high temperature environment. A parallel motion vibrating sample magnetometer was used for testing the magnet ic properties of the samples and several different magnetic properties were measured to characterize the microstructural processes of the deterioration. For detecting the induced magnetic anisotropy due to creep and thermal shock fatigue processes a novel parallel motion vibrating sample magnetometer (VSM) was developed in our department.

Keywords: vibrating sample magnetometer, creep, induced magnetic anisotropy, remnant life

[full-paper]