THE LATEST IMPROVEMENTS IN I-BEAMS PRODUCTION IN THE WORLD

Some specific aspects in the state of art regarding the improvements related to I-beams and parallel flanged I-beams production are presented in this paper. One practical solution in the variety of the conversions of the classical to the universal rolling stands is described in some more detail, as well as an overview of the latest improvements in I-beams and parallel flanged I-beams production in the world. So-called INP I-beams have tapered flanges v.s. parallel flanges concerned with parallel flanged I-beams, which are very difficult to be produced on classical rolling mills stands, but much easier and better to be produced on so-called universal rolling stands. Since the universal stands are expensive and are very difficult to fix at the existing rolling mills with classical rolling stands, then a conversion of classical to the universal rolling mills stands is the cheapest satisfactory solution. In a short overview are as well presented state of art technological improvements in parallel flanged I-beams production.&nbsp

Analiza uspješnosti supstitucije primijenjenog materijala pomoću parametara mehanike loma

By replacing the S355 conventional structural steel with V/Nb base micro-alloy steel it is possible to achieve a considerable reduction in the structure mass itself without safety risk, which is also proved by testing fracture mechanics properties of the materials. The numerical results have been also confirmed by analyzing the reliability of the selected materials, with special reference to safety from fracture hazard in the steel welded joints under consideration. Presented in the paper are the results of the numerical evaluation of the bridge crane steel structure under static and dynamic conditions for two steel grades and dimensions. This testing methodology can be applied to any kind of mechanical structure. It can also stress the importance of fracture mechanics application to the evaluation of the condition and behaviour of significant mechanical structures. The immediate effect of this investigation is the saving in the mass of the material used, together with a considerable fracture risk reduction, as well as an improvement in the working properties of the bridge crane steel structure.Zamjenom konvencionalnog strukturnog čelika S355 s mikrolegiranim čelikom na bazi V/Nb moguće je postići značajno smanjenje vlastite mase konstrukcije bez ugrožavanja sigurnosti što potvrđuju ispitivanja ponašanja materijala i sa aspekta mehanike loma. Numerička rješenja su potvrđena i kroz analizu sigurnosti izabranih materijala s posebnim osvrtom na aspekt sigurnosti od loma u zavarenom spoju predmetnih čelika. U radu su prikazani rezultati numeričke evaluacije čelične konstrukcije mosne dizalice u statičkim i dinamičkim uvjetima za dva kvaliteta i dvije dimenzije čeličnih limova. Primjenom navedene metodologije ispitivanja, koja se može implementirati na bilo koju vrstu strojarske strukture, kao konačan rezultat istraživanja dobiva se ušteda u masi ugrađenog materijala uz značajno smanjenje opasnosti od pojave loma i uz poboljšanje eksploatacijskih svojstava konstrukcije

Microstructural analysis of cold drawn CuAlMn shape memory alloy wire

The Cu-11.9Al-2.5Mn (wt. %) shape memory alloy was produced by vertically continuous casting technique obtaining bars of 8 mm in diameter which is applicable for plastic deformation. With the process of hot rolling and forging the 4.80 mm bar was produced. Afterwards, the obtained 4.80 mm bar was subjected to cold drawing process. After first run and after fourth run of cold drawing process the wire with diameter of 4.47 mm and 3.22 mm was produced, respectively. Optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) shown the insight in the samples microstructure. The as-cast state sample has two phase (α+β) microstructure. After cold working process the two-phase (martensite+α) microstructure appears. As the result of the cold working process it can be noticed a texture inside the sample depending on cold drawing direction. The microhardness of samples increases as the wires diameter decreases

Microstructural analysis of cold drawn CuAlMn shape memory alloy wire

The Cu-11.9Al-2.5Mn (wt. %) shape memory alloy was produced by vertically continuous casting technique obtaining bars of 8 mm in diameter which is applicable for plastic deformation. With the process of hot rolling and forging the 4.80 mm bar was produced. Afterwards, the obtained 4.80 mm bar was subjected to cold drawing process. After first run and after fourth run of cold drawing process the wire with diameter of 4.47 mm and 3.22 mm was produced, respectively. Optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) shown the insight in the samples microstructure. The as-cast state sample has two phase (α+β) microstructure. After cold working process the two-phase (martensite+α) microstructure appears. As the result of the cold working process it can be noticed a texture inside the sample depending on cold drawing direction. The microhardness of samples increases as the wires diameter decreases

Microstructural characterization of Cu82.3Al8.3Mn9.4 shape memory alloy after rolling

In this paper, the microstructure of Cu82.3Al8.3Mn9.4 (in wt. %) shape memory alloy after hot and cold rolling was investigated. The Cu82.3Al8.3Mn9.4 alloy was produced by a vertical continuous casting method in the form a cylinder rod of 8 mm in diameter. After the casting, hot and cold rolling was performed. By hot rolling a strip with a thickness of 1.75 mm was obtained, while by cold rolling a strip with a thickness of 1.02 mm was produced. After the rolling process, heat treatment was performed. Heat treatment was carried out by solution annealing at 900 °C held for 30 minutes and water quenched immediately after heating. The microstructure characterization of the investigated alloy was carried out by optical microscopy (OM), scanning electron microscopy (SEM) equipped with a device for energy dispersive spectroscopy (EDS). Phase transformation temperatures and fusion enthalpies were determined by differential scanning calorimetry (DSC) method. The homogenous martensite microstructure was confirmed by OM and SEM micrographs after casting. During rolling the two-phase microstructure occurred. Results of DSC analysis showed martensite start (Ms), martensite finish (Mf), austenite start (As) and austenite finish (Af) temperatures