Detection of Copper Precipitates in 15 NiCuMoNB5 (WB36) Steel by Using Micromagnetic NDE Techniques
I. Altpeter, G. Dobmann; IZFP, Germany
ABSTRACT
The material investigations presented confirm the results of earlier investigations 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 distortion 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 obtained from load stress-related Barkhausen noise measurements demonstrate that these micro-magnetic procedures are generally suitable for the detection of copper precipitation.
Publication Source: 3nd International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components, November 14-16, 2001, Seville Spain. Publisher: Tecnatom s.a. - [Homepage]
