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2000
Conference Paper
Title
Detection of Cu-Precipitates in Steel by Micro-Magnetic Nondestructive Techniques
Abstract
The ferritic steel WB 36 (15 NiCuMoNb 5 according to 1.6368) is applied in Germany in many fossil and nuclear power plants in piping with service temperatures up to 300°C. In fossil power plant applications in Europe some severe pipe damage occurred in components working in the temperature range of 320 - 350°C. In each case an enhancement of strength and a reduction of the Charpy notch energy was detected by destructive tests. Cu precipitation causes the effects. Load-dependent Barkhausen noise measurements were performed on different annealed microstructures and have revealed the residual stress effect of the Cu precipitates with an average value of 10-23 Mpa tensile stress in the ferrite matrix of the steel samples.