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Stainless steel is the most used metal all over the world. Since the corrosion resistance of steel is low in acidic medium and the use of acid in industry is very common, it is important to protect the steel from corrosion. In this study, the environmentally friendly nicotinamide compound was used as an inhibitor to protect steel from corrosion. In the study, firstly, the cyclic voltammetry technique was used to determine the electrochemical behavior of the steel in 0.1 M HCl acid solution. Then, Tafel Polarization Method in 0.1 M HCl acid solution was applied to determine the corrosion behavior of steel in the absence of nicotinamide inhibitor, in the presence of 500 ppm, 750 ppm and 1000 ppm nicotinamide. The optimum time was determined for each concentration by keeping the inhibitor at these 3 different concentrations for 0, 15, 30, 45 and 60 minutes. The highest inhibitory efficiency was found to be 96.8% in 1000 ppm nicotinamide concentration in 15 minutes holding time, and 96.6% at 500 ppm nicotinamide concentration in 60 minutes holding time in the absence of time limitation. The results obtained showed that nicotinamide can be used effectively in the protection of stainless steel from corrosion, and due to its environmental friendliness, corrosion protection is provided while not harming the environment and living things. [ABSTRACT FROM AUTHOR]

Low heat input, narrow HAZ, low stress strain and distortion, high welding speed, high penetration, smooth welding sections, high structural strength and automatic process are primary advantages of the laser welding. Moreover high efficiency and being economical leading less error rates are other advantages. In this work AISI 304, 50x40 mm stainless steel test items with 2,0 mm thickness were but laser welded. These 20x80 mm test items were tested in guidance with metallographic investigation, measuring hardness, three point bending test performed as explained in TS 282 EN 910 standards. According to the results, the solidified weld metal has the form of keyhole and full penetration has been determined. With increase of welding speed, weld width and depletion width between weld metal and base metal decrease. Hardness of the weld metal is getting higher from base metal to depletion zone. [ABSTRACT FROM AUTHOR]

In this study, porous surfaces made of SS316L spherical stainless steel powder have been produced to be used in heat exchangers of fuel cells by designing and producing forming die and special punches. Minimum pressure and temperature levels for compacting have been examined to obtain sufficient bonding between powders and the substrate. Moreover, surface roughness of the substrate has been increased in order to bond substrate and the powders. Surface etching techniques have been investigated and minimum surface roughness of the substrates has been defined. Besides, the effects of temperature and pressure on open porosity have been investigated. The experiments and the tests showed that 200 MPa compacting pressure, 500°C temperature and Ra=1.7 µm roughness, on the substrate are enough to realize such surfaces. Under these circumstances 29.6% porosity has been obtained. [ABSTRACT FROM AUTHOR]

In this study, effects of cemented carbide coated with TiC+TiN, coated with TiC, uncoated and CBN on the machinability of AISI 410 martensitic stainless steel was investigated. In the experiments chip root morphology, cutting forces and surface roughness were determined. Experiments were done in the dry turning conditions. The cutting speed, feed rate and depth of cut were kept constant as, 60 m/min, 0.12 mm/rev and 1.2 mm respectively. Cemented carbide tool coated with TiC+TiN gave maximum cutting forces. Although CBN gave the minimum cutting forces, it was observed that it fractured in a shorter machining length. The optimum values of cutting force and surface roughness were obtained from cemented carbide coated with TiC. [ABSTRACT FROM AUTHOR]

Metal/Ceramic joining technologies play a very important role in various aspects of the electronics and hightemperature component industries. Diffusion bonding is an advantageous technique for producing that type of joint since high-temperature mechanical resistance and defect-free interfaces can thus be achieved. However, one of the shortcomings of diffusion bonding is the high temperature needed for the bonding operation, which causes the development of high thermal stresses across the interface and fast growth of often undesirable reaction products. Usually, the residual stresses that originate from the metal are minimized by the addition of interlayer, which must be ductile and suitably reactive to both metal and ceramic in order to efficiently relieve the abovementioned thermal stresses. This study presents the weldability of the conventional stainless steel and prepared porous ceramic by diffusion welding. Different wetting materials (Ag, Cu and Ag-Cu-Ti alloy) with a thickness of about 100 µm were used with loading of 0.2 and 2 MPa pressures under vacuum-argon atmosphere and the applied temperatures were between 850, 875, and 900 °C for 45 minutes. The microstructure of metal-ceramic interface was investigated by scanning electron microscope (SEM) with EDS attachment for chemical analysis. The pores of the ceramic were filled with the Ag or its eutectic alloy through the interface with a thickness at about 40-60 µm. The joining mechanism of the stainless steel to ceramic was discussed with respect to diffusion and infiltration. [ABSTRACT FROM AUTHOR]