Quality of circuits, mainly, is defined(determined) by quality of
steel of which they are made(produced).
Now there are two ways of manufacture of circuits: welding from rolling steel and moulding.
Comparison of mechanical properties
Welded circuits are made of rolling steel — steel rod welds in parts of a circuit of various geometry. Hire fusible on steel foundries and then hire in rod various diameter. In such a way it is possible to receive normal (carbonaceous) and heat resisting steel.
Rod receive by hot proskating rinks(prorolls) of steel ingots in weight up to 6 т. The greater(big) degree of deformation leads to study of structure rod in diameter 22-25 mm on all section. It provides dense homogeneous fine-grained structure rolling rods, that sharply distinguishes it(her) from cast steel which possesses more coarse-grained structure and consequently, and greater fragility. As a result of it(this) welded circuits are much stronger and stability to loadings, than cast. It proves to be true that for rise of heavy cargoes welded circuits are used only. Durability of our circuits increases also owing to use of the technology, allowing to make a part of a circuit of all with one welded seam. It completely excludes breakage of a circuit.
During manufacture rolling steel is exposed to strict quality assurance on each repartition. It allows to exclude undesirable defects (times, bowls, slag inclusions) and to receive metal of absolute(hundred-percent) quality. On all kinds of steel hire the certificate of quality of a factory of the manufacturer stands out. Presence of a welded seam also is not "Ahilesovoy the fifth" a welded circuit since durability of the seam is high enough, and easing of metal in about a seam to a zone at observance of technology of welding occurs(happens) on very insignificant size.
Cast circuits are made by casting in the set forms of steel of corresponding(meeting) structure. By such manufacture steel possesses more coarse-grained structure. Such circuits turn out fragile and are more subject deleting (a principal cause of deterioration of a circuit in a rotating furnace) rather than welded circuits from rolling steel.
In cast circuits the probability of undesirable inclusions — bowls, slag is great, etc., that leads to reduction of service life. In order to prevent it(this) and achievement of a degree of quality of a welded circuit ultrasonic and x-ray quality assurance of circuits of all party(set) is necessary , that for economic reasons is not made.
Comparison of thermal stability
Heat resisting qualities of steel directly depend on a degree of its(her) resistance to formation(education) of scale. Increase stability to steel is promoted by such alloying elements as chrome, silicon, the aluminium, promoting formation(education) on a surface proof oxidfilms which reduce speed of oxidation at heats. Solving(deciding) influence on stability renders carbidcreation an element — chrome. Cast circuits at the same maintenance(contents) in steel of chrome, silicon and aluminium, as welded circuits, possess smaller heat resistance owing to smaller physical density.
As a result of the above-stated comparison it is necessary to draw a conclusion, that the welded circuit will possess the best mechanical properties and higher thermal stability, than a cast circuit from the same mark of steel, as a result of it(this) service life of a welded circuit considerably above cast.
Popular belief in that the welded seam is unreliable, and process of welding leads to deterioration of mechanical properties of metal actually is incorrect since at a correct choice of a method of welding and corresponding(meeting) electrodes the structure of metal turns out enough dense, homogeneous, that affects durability of a seam which can reach(achieve) 100 kg/¼¼2.
The only thing plus of cast circuits is their a little bit smaller cost, in comparison with welded circuits. However, smaller service life of cast circuits leads to their greater charge, to more frequent stop furnaces for replacement of the failed circuits, that undoubtedly affects the cost price of production.