International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

CMT technology provides significant advantages, such as reduced deformation due to high temperatures, high welding speed and a significant reduction in spatter compared to the MIG/MAG method. The experimental work was focused on verifying the possibility of renovating the surfaces of molds for high-pressure aluminum casting using CMT technology. A mold wear analysis was performed and a method of restoring functional surfaces was proposed. Two types of additive materials were used – Thermanit 625 and Thermanit X. The quality of the layers was evaluated by SEM, EDX microanalysis and the coefficients of friction of the layers were determined by the Ball-ondisc method. The renovation layers were also subjected to an immersion test in Al alloy at 680 °C.

AISI 316Ti stainless steel is prone to local corrosion in aggressive chloride environments. Its resistance to pitting in the absence and presence of molybdate inhibitor was tested by two independent tests with different mechanisms of corrosion process: by exposure (24 hours immersion test) and electrochemically (potentiodynamic polarisation test). Both tests were carried out in 1 M chloride acidic solution without inhibitor and with two different amounts of added inhibitor (concentration ratio inhibitive/aggressive anions was 1:10 and 1:20 respectively), at room temperature. Results of immersion tests were evaluated on the bases of corrosion rates calculated from corrosion losses during immersion and by morphology of pitting. Results of potentiodynamic polarisation tests were evaluated by pitting potentials.

Austenitic stainless steels are widely used for various industrial, construction and biomedical application because of their high resistance to uniform corrosion and suitable mechanical properties. However, they are prone to local corrosion in aggressive halides environments. In contrast of corrosion resistance research in chloride containing environments, there have been few investigations into the effect of fluorides on passivity breakdown and pitting corrosion of stainless steels. This article focuses on the effect of fluoride added to chloride solution on corrosion resistance of AISI 316L stainless steel. Evaluation is based on results of exposition immersion tests performed in 0.9 % NaCl, 0.9 % NaCl + 0.05 % NaF and 0.9 % NaCl + 0. 5 % NaF solutions (42 days) and on results of cyclic potentiodynamic polarization tests performed in the same solutions.