Seamless steel tubes for pressure purposes. Technical delivery conditions

2020 ◽  
Vol 304 ◽  
pp. 121-125
Author(s):  
Martin Necpal ◽  
Mária Kapustová ◽  
Maroš Martinkovič

The most comprehensive steel tube portfolio is used to produce all kinds of modern energy production and the corresponding auxiliary unit such as boilers and heat exchangers. Multi-rifled seamless steel tubes are distinguished by maximum pressure, heat resistance, strength and durability. Production of multi-rifled seamless steel tubes by cold draw process using multi-rifled mandrel is quite a new technology. Shape and dimension of the drawing tool depend on drawing tube reduction degree, i. e. on the original diameter of the initial tube and final diameter of the tube. The technology of drawing tubes is influenced by process parameters, dimensions of tools and cold forming process conditions. Optimization of the whole forming process naturally involve the FEM analyses and simulation. One of the most important information of the cold drawing process is the load stroke of the tools. The contribution is concerned at the usability of FEM simulation on an evaluation of cold draw forming process condition and prediction of load stroke of the forming tools. DEFORM 2D/3D FEM software is used to compare the result of the drawing force and to determine the appropriate methodology to set FEM simulation of cold forming.


2016 ◽  
Vol 716 ◽  
pp. 988-993
Author(s):  
Milan Mojžiš ◽  
Martin Ridzoň ◽  
Peter Bella ◽  
Maroš Martinkovič ◽  
Ľudovít Parilák

The production of precision seamless steel tubes in Železiarne Podbrezová is using hot rolled tubes with multiple cold drawing passes and intermediate annealing. It utilizes intensive plastic deformation during cold drawing, taking full advantage of the microstructural state from a physical point of view. In this paper, optimization of technological processes for cold drawn tubes made from ferritic-pearlitic steel has been elaborated. We use microstructural and substructural analysis, dislocation hardening theory and stress analysis. The subject of this article is the experiment with multiple drawing passes and intermediate annealing for production of precision steel tubes with dimensions of 31.8 x 2.6 mm. The drawing itself consists of 5 processes (also called „runs“) with 7 drawing passes in total. The results presented show strain hardening of the material after drawing along with relaxation mechanism during intermediate annealing. The possibility of utilizing the microhardness values on intensity assessment of these processes is investigated, too.


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