Texture, microhardness and corrosion resistance of 316L stainless steel

The texture, microhardness, and corrosion resistance of cold worked 316L steel were evaluated. The X-ray diffraction analysis in particular permitted to disclose and identify the main textures variations in the structure of the investigated steel after its deformation within the range 10 - 80%. The corrosion resistance was studied using Tafel polarization tests. It was shown that the increase in deformation degree drastically decreases the relative intensity of {111} planes. Besides, with high degree of cold deformation microhardness increases while corrosion resistance deteriorates.    This article has been retracted. Link to the retractio

Influence of annealing heat treatment on pitting corrosion resistance of stainless steel type 316

The effect of annealing heat treatment on pitting resistance of stainless steel type 316L has been studied using Tafel polarization and ASTM G150 for estimating of the pitting potential and CPT, respectively. The materials were tested in 3.5% NaCl solution. The chemical composition of the material was analyzed via optical emission spectrometry. It was found that the sample treated at 940 °C shows better pitting corrosion resistance than samples treated at 520 °C and 820 °C. The treatment at 940 °C produced two types of morphologies, austenitic-ferritic matrix with δ-ferrite and only small amount of the σ phase. In the range up to 820 °C the σ phase embedded in the γ phase matrix and at δ/γ interface was causing brittleness of the material and aggravated corrosion resistance. The treatment at 940 °C produced the microstructure which prevented the corrosion attack to develop. It was revealed that the pitting size in samples treated at 520 °C and 820 °C is greater than that at 940 °C. In addition, depth of pitting has been considered as a factor of pitting corrosion resistance. The depth of pitting in sample treated at 940 °C is low since the pitting is almost superficial, while the pitting size in samples treated in 520 °C and 820 °C is higher and deeper.  http://dx.doi.org/10.5937/metmateng1402097

Influence of annealing heat treatment on pitting corrosion resistance of stainless steel type 316

The effect of annealing heat treatment on pitting resistance of stainless steel type 316L has been studied using Tafel polarization and ASTM G150 for estimating of the pitting potential and CPT, respectively. The materials were tested in 3.5% NaCl solution. The chemical composition of the material was analyzed via optical emission spectrometry. It was found that the sample treated at 940°C shows better pitting corrosion resistance than samples treated at 520°C and 820°C. The treatment at 940°C produced two types of morphologies, austenitic-ferritic matrix with δ-ferrite and only small amount of the σ phase. In the range up to 820°C the σ phase embedded in the γ phase matrix and at δ/γ interface was causing brittleness of the material and aggravated corrosion resistance. The treatment at 940°C produced the microstructure which prevented the corrosion attack to develop. It was revealed that the pitting size in samples treated at 520°C and 820°C is greater than that at 940°C. In addition, depth of pitting has been considered as a factor of pitting corrosion resistance. The depth of pitting in sample treated at 940°C is low since the pitting is almost superficial, while the pitting size in samples treated in 520°C and 820°C is higher and deeper. http://dx.doi.org/10.5937/metmateng1402097

Texture, microhardness and corrosion resistance of 316L stainless steel

The texture, microhardness, and corrosion resistance of cold worked 316L steel were evaluated. The X-ray diffraction analysis in particular permitted to disclose and identify the main textures variations in the structure of the investigated steel after its deformation within the range 10 - 80%. The corrosion resistance was studied using Tafel polarization tests. It was shown that the increase in deformation degree drastically decreases the relative intensity of {111} planes. Besides, with high degree of cold deformation microhardness increases while corrosion resistance deteriorates.  This article has been retracted. Link to the retractio

Improved pitting corrosion resistance of S.S 316L by Pulsed Current Gas Tungsten Arc Welding

In this study, S.S 316L was welded using Direct Current Gas Tungsten Arc Welding (DGTAW) and Pulsed Current Gas Tungsten Arc Welding (PGTAW) methods. Optical observations, scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) were employed to study the effect of continuous and pulse currents on microstructure and phase transformation in weld metal (WM). In addition pits morphology were evaluated by SEM. The corrosion behaviour was analyzed using cyclic polarizaton tests and Mott-schottky measurements. The pulse current resulted in finer grain and more ferrite in WM. This can be due to the decrease in heat input and higher cooling rate encouraged by pulse current. Cyclic potentiodynamic polarization tests showed that the WM of sample produced by pulse current show higher corrosion and pitting resistances than that in sample produced by continuous current. The reason is attributed to lower segregation of solute elements such as chromium and molybdenum into the delta-ferrite and also finer grain size produced in WM due to lower heat input and higher cooling rate. Both of these factors increase the stability of passive layer formed. The results showed that the corrosion behaviour of WM in both conditions (pulse and continuous current) is higher than the base metal (BM). This fact is attributed to the presence of ferrite bands formed in BM due to the segregation of alloy elements. The Mott-schottky plots confirmed that the passive layer formed on welded samples was an n-type semiconductor. The results showed that the samples showed less pitting resistance contained more oxygen vacancies in their passive film structure. It is also concluded that the breakdown of passive layer and pitting formation obey point defect model (PDM). Keywords: S.S 316L, Pulsed Current Gas Tungsten Arc Welding (PGTAW), lacy ferrite, vermicular ferrite, Pitting corrosion, Mott- Schottky