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Under high electric current, the material property and stress field near the notch tip in the stainless steel plate have been investigated. Using the numerical and experimental methods, the electric current density, temperature, stress, grain image and micro hardness are obtained. Also, the melting and heat-affected zones at the notch tip are investigated. At the tip region, the hardness value improves and the compressive residual stress occurs. This result can reduce the stress level and prevent from the crack initiation when the plate is subjected to the tensile load.

Abstract: Structures, strain, polarization, and dielectric permittivity of lead-free piezoceramics (1−x)(Bi0.5Na0.5)TiO3–xBaTiO3 for x=0.03, 0.07, and 0.11 (abbreviated as BNB3T, BNB7T, and BNB11T) have been investigated systematically as functions of electric (E) field and temperature. The results revealed that the piezoelectric behavior was significantly influenced by the domain configuration which depends on composition, E field, and lattice structure. The E-field induced strain in BNB7T composition can reach S max/E max=475pm/V, which is comparable with the soft Pb(Zr,Ti)O3 (PZT) piezoceramics. The large field-induced strain is likely originated from the development of the nano-polar regions (or clusters) with sizes of ~5–10nm, which could reduce the energy barriers of dipole reorientation (or switching) under E-field application. [Copyright &y& Elsevier]