An Improved Ultrasonic Imaging Method for Austenitic Welds Based on Grain Orientation Distribution Inversion Algorithm
- PDF / 4,228,124 Bytes
- 14 Pages / 595.276 x 790.866 pts Page_size
- 75 Downloads / 214 Views
An Improved Ultrasonic Imaging Method for Austenitic Welds Based on Grain Orientation Distribution Inversion Algorithm Haipeng Zhou1 · Zandong Han1,2,3 · Dong Du1,3 Received: 13 January 2020 / Accepted: 18 June 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Traditional ultrasonic imaging inspection does not perform well for austenitic welds, in which the defect locating accuracy is insufficient due to the distortion of propagation paths caused by the weld’s anisotropy and inhomogeneity. The distribution of grain orientation (DGO) contributes to the velocity distribution in austenitic welds and influences the ultrasonic propagation paths. An improved ultrasonic imaging method for austenitic welds based on a DGO inversion algorithm is proposed in this paper. A DGO model is established using an iterative disturbance method of local parameters. The model is optimized by an evolution strategy based on the model error evaluated by propagation times of known reflectors. Inspection experiments were carried out, in which a reference specimen was used to acquire the DGO inversion result and the inspection images of a target specimen were generated based on the optimized DGO model. Experimental results have proved that the improved ultrasonic imaging method can obviously increase the defect locating accuracy and effectively improve the imaging performance for austenitic welds. Keywords Austenitic weld inspection · Grain orientation distribution · Ultrasonic imaging · Improved TFM
1 Introduction Austenitic welds are widely applied in stainless steel components of many important facilities, such as the pressurized vessels in nuclear reactors, the turbine blades in hydropower stations and so on. Ultrasonic imaging inspection by array transducers is usually required to assure the structural integrity of welds, which can provide two-dimensional (2D) B-scan images of more information than one-dimensional (1D) A-scan signals. A B-scan image is a sectional image of the inspection plane, generated by rearranging a series of A-scan signals according to certain rules, which can help to analyze the sizes and locations of the defects.
* Zandong Han [email protected] 1
Department of Mechanical Engineering, Tsinghua University, Beijing 100084, People’s Republic of China
2
State Key Laboratory of Tribology, Tsinghua Universisty, Beijing, People’s Republic of China
3
Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing, People’s Republic of China
However, ultrasonic imaging inspection does not always perform well for austenitic welds. During the welding process of the austenitic stainless steel, a lot of coarse columnar grains grow up in the weld area [1]. There are obvious signal scattering and energy attenuation caused by coarse grains, which will influence the defect’s detectability [2]. Besides, the coarse-grained microstructure often brings obvious anisotropy and inhomogeneity. The weld’s anisotropy means that the single grains have anisotro
Data Loading...
