A Comprehensive Numerical Model for One-Dimensional Pit Growth of 316L SS under a Salt Film

A comprehensive mathematical model, including electrode kinetics, hydrolysis and complexation reactions, salt film precipitation and pit interface movement, was developed to investigate pit growth of stainless steels 316L under a salt film. The new mathematical framework incorporates activity coefficients into the hydrolysis and complexation reaction calculations for the first time, using experimental results to parametrize the electrode kinetics in a saturated pit solution. The model was validated by 1D pit experiments and results documented in the literature. It can successfully estimate the transition potentials, salt film thickness, pit stability product, saturated pit concentration, and the pH at the pit base during pit propagation under the presence of a salt film. Moreover, the model can predict the Cr enrichment and Fe depletion in the saturated solution at the pit base, attributed to the higher diffusion coefficient of Fe and the lower Cr diffusivity.

Simulation Process Deep Drawing of Tailor Welded Blanks DP600 and BH220 Materials in Tool With Elastic Blankholder

The high-strength steels and tailor welded blanks (TWB) are applied in construction of cars parts to reduction of cars weight [1, 2]. The application of these materials brings possible complicatons during the forming when it proves the considerable influence of stress-strain characteristics differences of of the individual parts of TWB what result in non-constant material flow and consequently a negative movement of the weld interface [3, 4]. One of the ways of elimination of this negative effect is to choose a suitable blankholder system with optimal distribution of blankholder forces by using elastic blankholder with adjustable distribution of blankholder forces. Within the bounds of study the experimental blankholder system with elastic blankholder with adjustable distribution of blankholder forces was used [5, 6]. Finite element methods (FEM) simulation has unsubstitutable role n the study of formability of TWB whereby it is possible to determine the values and points of application of the blankholder forces [7, 8]. The FEM simulations results carried out in simulative LS-Dyna software are presented in this article which is focused on achieving weld interface movement minimalization of tailor welded blanks from DP600 and BH220 materials by optimization of blankholder forces [9, 10].

Diffusion-Controlled Growth of Oxygen Bubble Evolved from Nanorod-Array TiO2Photoelectrode

Nanorod-array structure gains its popularity in photoelectrode design for water splitting. However, the structure’s effects on solid-liquid interface interaction and reaction product transportation still remain unsolved. Gas bubble generally evolved from photoelectrodes, which provides a starting point for the problem-solving. Based on this, investigations on the gas-evolving photoelectrode are carried out in this paper. By experimental studies of wettability on the photoelectrode nanorod-array surface and oxygen bubble growth from anode, we analyzed the interaction affecting the gas-solid-liquid contact behaviors and product transportation mechanism, which is controlled by diffusion due to the concentration gradient of dissolved gases in the aqueous electrolyte and the microconvection caused by the bubble interface movement. In the end, based on the bubble growth characteristics ofRB(t)~t0.5in the experiment, a model describing the product transport mechanism was presented.