Volume 14 (2014): Edition 2 (June 2014)

The article discusses the issues related to concrete shrinkage. The basic information on the phenomenon is presented as well as the factors that determine the contraction are pointed out and the stages of the process are described. The guidance for estimating the shrinkage strain is given according to Eurocode standard PN-EN 1992-1-1:2008. The results of studies of the samples shrinkage strain of concrete C25/30 are presented with a comparative analysis of the results estimated by the guidelines of the standard according to PN-EN 1992-1- 1:2008

The paper presents an analytical evaluation of transition temperature from upper to lower bainite in Fe-C-Cr steel. The calculations was based on the model constructed by Matas and Hehemann which involves a comparison between the times needed to precipitate cementite within the bainitic ferrite plates (t_θ), with the time required to decarburise supersaturated ferrite plates (t_d). The transition between upper and lower bainite is found to occur over a narrow range of temperatures (350-410°C) and depends on the thickness of bainitic ferrite laths and the volume fraction of precipitated cementite. On comparing the td and tθ times it was found that the transition temperature from upper to lower bainite reaction (LS) of about 350oC could be predicted if the thickness of bainitic ferrite laths is set as wo = 0.1 μm and volume fraction of cementite is set as ξ = 0.01

The cellular structure and unique properties of aluminum foams are the reason of problems concerning their cutting and bonding. The content of the paper includes characterization of the essence of properties and application of aluminum foams, limitations and chances of aluminum foams soldering. The aim of the research is consideration of possibilities and problems of soldering AlSi foams and AlSi - SiC composite foams as well as mechanical properties. The possibility of soldering AlSi foams and AlSi - SiC composite foams using ZnAl solders was confirmed and higher tensile strength of the joint than the parent material was ascertained

Wet welding with the use of covered electrodes is one of the methods of underwater welding. This method is the oldest, the most economic and the most versatile. The main difficulties during underwater wet welding are: high cooling rates of the joint, the presence of hydrogen in the arc area and formation of hard martensitic structure in the weld. These phenomena are often accompanied by porosity of welds and large number of spatters, which are more advanced with the increase of water depth. In this paper result of non-destructive tests, hardness tests and metallographic observations of S500MC steel joints performed underwater are presented. The weldability of 500MC steel at water environment was determined

The effect of the fiber orientation in a laminate is investigated experimentally when subjected repeated quasistatic indentation. All the laminates with different fiber orientation are subjected to indentation with a stainless steel spherical indenter of diameter 8.0mm on a universal testing machine for a maximum indenter displacement of 4mm. The rate of indenter displacement was 0.5mm/minute. Different parameters like load bearing capacity, indentation diameter, area of surface damage, etc., were recorded after 4mm of indenter displacement. All the parameters were studied and compared to evaluate the laminate with high strength