Effect of Twice Stablizing Heat Treatment on the Properties of 347H Stainless Steel

In this study, the mechanical properties and intergranular corrosion properties of 347H austenitic stainless steel were studied by tensile test, impact test, double-ring electrochemical potentiodynamic reactivation test (DL-EPR) and microstructure observation in three states of solution, primary and twice stabilized state. Results showed that the key mechanical properties of 347H stainless steel under three different conditions had little change, and the mechanical properties at room temperature were not affected by the stabilizing heat treatment. After 12h of sensitization, the solution material showed obvious sensitization behavior, and the Ir/Ia index exceeded 0.3, indicating that the material entered the range of complete sensitization. Both primary and twice stabilizing heat treatment can significantly reduce the occurrence time of sensitization and prevent the sensitization process. However, the stabilizing heat treatment cannot completely prevent the material sensitization, and it must be combined with other methods .

Photo-driven self-powered biosensor for ultrasensitive microRNA detection via DNA conformation-controlled co-sensitization behavior

We developed a photoelectrochemical enzymatic fuel cell-based self-powered biosensing platform for microRNA detection via DNA conformation change-controlled co-sensitization behavior.

Measurement and analysis on the sensitization behavior of SS-304 welds using Nb-based stabilization through flux-coated gas tungsten arc welding

The objective of this research work is to enhance the microstructure and intergranular corrosion resistance of AISI 304 stainless steel by diffusing the stabilizing element, that is, Niobium (Nb), using a comparatively new methodology termed as flux-coated gas tungsten arc welding. In this process, a suitable material in powder form (pure Nb powder of size < 20 μm) is mixed with acetone and then coated on the V-joint of the plates before welding. The welded joint’s surface microstructure and chemistry have been analyzed by optical microscopy, scanning electron microscopy and energy-dispersive x-ray spectroscopy. The microstructural results demonstrate that the diffusion of Nb changes the ferrite morphology of the weld joint to lathy ferrite from vermicular ferrite because of an increase in supercooling during solidification. The results of the investigations indicate that the flux-added weldments exhibited 26 HV more microhardness than conventional welded weldments in the fusion zone. Furthermore, the corrosion behavior of both gas tungsten arc welding–treated and flux-coated gas tungsten arc welding–treated weldments has been evaluated by the double-loop electrochemical potential kinetic reactivation test. The latter revealed that Nb-diffused weldment features insulative and protective properties and displays zero degree of sensitization, whereas conventional welded weldment gives a degree of sensitization of 2.53.