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2003
Conference Paper
Titel
Detection of copper precipitates in 15 NiCuMoNb5 (WB 36) steel by using micromagnetic NDE techniques
Abstract
The material investigations presented confirm the results of earlier investigatins with a conclusion that the service-induced hardening and decrease in toughness in WB 36 materials are caused by the precipitation of copper. In the initial state of the material, only a part of the alloyed copper is precipitated. The other part is still solved and can be precipitated during long-term operation at temperatures above 320°C to 350°C. The copper precipitation leads to a ditortion of the crystal lattice surrounding the copper precipitates and yields internal micro-stresses. If the number and size of the copper precipitates change during operation of a component, a change of the residual-stress level occurs. The results obained from load stress-related Barkhausen noise measurements demonstrate that these micro-magnetic procedures are generally suitable for the detection of copper precipitation.
Language
English