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Effect of heat treatment on the microstructure and mechanical properties of a low-carbon X80 pipeline steel

100%

Acosta-Cinciri B. C. , López-Granados N. M. , Ramos-Banderas J. A. , Hernández-Bocanegra C. A. , Garnica-González P. , López-Corpus J. A.

tom Vol. 39, No. 1

103--112

In this work, the effect of heat treatment conditions on the microstructure and mechanical properties of an American Petroleum Institute (API) X80 steel with a low carbon content of ~0.02% wt., destined for the manufacture of pipelines and pipeline transmission systems by welding, was investigated. Samples were heat treated under different conditions and then were characterized by scanning electron microscopy (SEM), orientation image microscopy (OIM), and electron backscattered diffraction (EBSD). The results showed that when the steel is fastly cooled from the austenitic field (990°C), the mechanical properties increase significantly [ultimate tensile strength (UTS) >1,100 MPa, yield strength (YS) 900 MPa, and elongation 27%] due to the high percentage of martensite (M) present in the microstructure (95%). In contrast, when the cooling rate decreases and the treatment conditions remain at/or above the bainitic/martensitic transformation (from 990°C to 600°C and 450°C), the mechanical properties are decreased by almost 50% because of the decrease in the percentage of martensite (18%). However, the percentage of elongation increases significantly (38%) due to the presence of other micro-constituents resulting from the phase transformation. On the other hand, the best combination of mechanical properties (UTS above 800 MPa and YS between 610 MPa and 720 MPa) was obtained when the steel acquired a dual-phase microstructure [(martensite/austenite)-(ferrite/martensite)] since the amount of martensite is conserved between 45% and 82%, in combination with the other micro-constituent present in the steel that allows us to achieve elongation percentages close to 30%.

CURRENT RESULTS ON THE NEUROSCIENCE OF INTELLIGENCE

100%

Németh K.

tom 66

nr 2

381-396

Due to the last two decades of escalated technical development IQ researchers nowadays have to integrate some new pieces of empirical evidence coming from neuroscience. At the beginning of the 21st century the research of the neural background of intelligence arrived to a new chapter owing to the simple availability of functional imaging techniques, like fMRI and other neuro-physiological methods (e.g. EEG). To extend our results and to move on we need to clarify the relationship of data and organize our knowledge. In this review we summarize results on the neural background of intelligence that derive from clinical or normal, child or adult samples. The data suggest that intelligence is supported by a distributed integrated neural network.

Frequency Dependent Mismatch Correction Scheme for Zero-IF Receivers

72%

Hibner R. , Zieliński R. J.

tom Vol. 64, No. 1

13--18

This paper shows effective method of linear distortions compensation in zero-IF receivers. With application of frequency domain processing a computation efficient method was developed that allows to correct quadrature mismatch in Zero-IF receiver along with gain and group delay independent of receiving signal type. Method was implemented and tested on hardware platform confirming its effectiveness. This method makes it possible to build high sensitivity devices to monitor spectrum in very wide frequency ranges.