Volume 47, Issue 4

In welding technology, joining processes of different materials, which have dissimilar crystal structures are difficult. Welding of different materials becomes very important to reduce costs. Furthermore, the friction welding method is processed in lower temperature than the melting temperature. Especially, this is a big advantage to overcome difficulties that occur in the heat affected zone during usage of conventional methods. In this study, the weldability of AISI 304 stainless steel and AISI 1040 carbon steel by friction welding is studied. During the welding process, temperature variations in the welding zones were measured with an infrared temperature measurement device. After welding of the samples, tensile and hardness experiments were carried out. For metallographic investigations, optical microscope and scanning electron microscope (SEM) pictures were taken. Energy dispersive spectroscopy (EDS) analysis was carried out for composition investigations on welding and heat affected zones. As a result, these two steels could be joined by friction welding for industrial usage.

It is well known that the interlamellar spacing controls the mechanical properties of any material with a lamellar microstructure. It is also expected, although not yet established, that varying distribution of interlamellar spacing would also influence the properties. However, the problem of determining the distribution of interlamellar spacing from metallographic observations made on single 2D sections is almost intractable. A technique to estimate the true interlamellar spacing in a lamellar microstructure, using a 3D probe referred to as a disector, has been developed. This disector technique was used to obtain the distribution of true interlamellar spacing of pearlite in a microalloyed steel. The results indicate clearly that there is a significant variation of interlamellar spacing across pearlite colonies and also within individual colonies. In addition, it was possible to determine the overall distribution of interlamellar spacing.

Al-Mg alloy was friction stir processed (FSP) incorporating two different sized SiC particles. Reduction of particle size after FSP was very significant with coarser SiC particles than finer. The density of SiC particles in FSP nugget was found to be uniform from top to bottom with coarser SiC particles, whereas it was more at the bottom than the top with finer. Tool wear after FSP was found to be relatively more with coarser particles than finer.