-
Date submitted2019-04-04
-
Date accepted2019-08-04
-
Date published2020-04-24
Chemical heterogeneity as a factor of improving the strength of steels manufactured by selective laser melting technology
The aim of this paper was to establish the causes of the heterogeneity of the chemical composition of the metal obtained by the LC technology. The powdered raw material was made from a monolithic alloy, which was fused by the SLM, the initial raw material was a laboratory melting metal of a low-carbon chromium-manganese-nickel composition based on iron. To determine the distribution pattern of alloying chemical elements in the resulting powder, electron-microscopic images of thin sections were combined with X-ray analysis data on the cross-sections of the powder particles. As a result, it was found that transition (Mn, Ni) and heavy (Mo) metals are uniformly distributed over the powder particle cross-sections, and the mass fraction of silicon (Si) is uneven: in the center of the particles, it is several times larger in some cases. The revealed feature in the distribution of silicon is supposedly due to the formation of various forms of SiO 4 upon the cooling of the formed particles. The internal structure of the manufactured powder is represented by the martensitic structure of stack morphology. After laser fusion, etched thin sections revealed traces of segregation heterogeneity in the form of a grid with cells of ~ 200 μm.
-
Date submitted2009-10-18
-
Date accepted2009-12-17
-
Date published2010-09-22
Reuse of development workings as an element of providing the effective coal output
- Authors:
- M. A. Ilyashov
The article contains the results of application in a coal mine of a combined way for protection and support of development workings. This method combines a frame support, anchors and a cast support strip erected behind the longwale. The geomechanical substantiation of technological parameters, regulations and the field for efficient use of this method are given. Its introduction has allowed to increase the loads on longwale and to lower labour content and expenses for maintenance of butt entries.