Influence of Compound Deoxidation of Steel with Al, Zr, Rare Earth Metals, and Ti on Properties of Heavy Castings

Influence of Compound Deoxidation of Steel with Al, Zr, Rare Earth Metals, and Ti on Properties of Heavy Castings Heavy steel castings deoxidized with aluminium are sometimes brittle intercrystalline failed during their service along primary grain boundaries what is initiated by aluminium nitrides and so called conchoidal fractures are formed. The tendency to forming the conchoidal fractures depends in particular on cooling rate (the casting modulus), aluminium and nitrogen contents in steel. During deoxidation, when manufacturing heavy castings, the elements with high affinity to nitrogen, zirconium or titanium, are added to steel that would decrease nitrogen activity by the bond on stable nitrides. The formation of stable nitrides should reduce the tendency of steel to the formation of conchoidal fractures. Deoxidation was thermodynamically analyzed at presence of the mentioned elements. For particular conditions a probable course of deoxidation was estimated at test castings. The deoxidation course was checked by microanalysis of deoxidation products (inclusions). For service and experimental castings the anticipated composition of inclusions was compared. It has been proved that in heavy castings with high aluminium contents in steel under studied conditions neither the addition of zirconium nor of titanium nor of rare earth metals will prevent the formation of conchoidal fractures.

THE INFLUENCE OF SYNTHETIC POLYSACCHARIDE ON BOTH EFFICIENCY OF SYMBIOSIS AND PEROXIDASE AND CATALASE ACTIVENESS OF PEA AND SOYA BEANS

The influence of synthetic polysaccharide MOD-19 on the effic¬iency of nitrogen fixation ofpea and soya plants as well as on ferment activity of the antioxidative defense system - peroxidase and catalase was investigated. It has been shown that the metabolic process intensifying is ob¬served in pea and soya plants grown from the seeds, wich had been tilled before sowing by nodule bacterium (pea - Rhizobium leguminosarum bv. viciae 263b and soya beans - Bradyrhizobium japonicum 634b) and by nonspecific for these bean cultures polysaccharide MOD-19. This has been proved by morphological and functional haracteristics of these systems, the increasing of plant biomass and nodules quantiity on the roots. The active functioning period of nodules is elongating at the expense of secondary nodules formation on the side roots and their nitrogen activity increased. Rising of the oxidative ferment activity level for peroxydase and catalase was found in these plants.