Continuous casting, initially introduced in 1840, is an attractive method in mass producing semi-finished metal shapes (slabs, blooms, and billets) from molten metal. More than 50% of current world’s steel production is produced by continuous casting. Today, annually 750 million tons of steel in the steelmaking operation, 20 million tons of aluminum and many tons of other alloys are directly cast from molten metal by continuously casting method [1]. This paper presents a short review over the processes in consciously cast steel.

The microstructure of steel is responsible for the macro-behavior of steel or in other words steel’s material properties. Surface microcracks and internal flaws can be introduced to steel microstructure during solidification. The soundness of the steel is altered by formation of flaws and microcracks in casting production line. Additive elements to molten steel and chemical element and alloys in the iron slag may produce indigenous and exogenous inclusions in the microstructure. The presence of the inclusions in the microstructure changes the cleanliness of the steel and affects the material properties of the steel products. This paper is a review of literatures on the sources of formation of inclusions and flaws in the as-cast steel and the effect of these defects on the microstructure properties.

The influence of solution annealing heat treatment on the microstructure and hardness of Hadfield steel containing up to 3.16% chromium and 0.15% nitrogen was investigated.
Furthermore, the effects of chromium additions on the hardness and microstructure of austenitic manganese steels in the as-cast and heat-treated conditions have been studied. The true stress-true strain response of nitrogen alloyed austenitic manganese steel with chromium additions in the as-cast and heat treated conditions under compression loading was also studied. The microstructural observations on the as-cast and heat-treated steels with chromium additions revealed the stability of austenite phase in the as-cast state deformation with precipitation of carbides and carbonitrides on the grain boundaries. These precipitates increase by increasing true strain and chromium content.
2² factorial design was used to investigate the contribution effect of chromium additions and true strain on hardness of austentic manganese steel as cast and after heat treatment. The contribution of both chromium additions up to 3.16%, true strain rate up to 0.4, and the interaction combination effect of them were determined of cast and heat treated austenitic manganese steel. The regression models were built up to identify the hardness as function in chromium additions and true strain rate of both cast and heat treated austenitic manganese steel.

The effect of direct reduced iron (DRI) addition in metallic charge on the different steel making parameters and consumption figures have been studied. Data obtained from industrial heats carried out in 185-ton electric arc furnace (EAF) were used to study. The present study carried out in a wide range of DRI percentage, 0 - 50% of metallic charge, and the results have been statistically analyzed to correlate the percentage of DRI with the different consumption figures of electric energy, oxygen, coke and fluxing materials. In addition, the influence of DRI percentage on contents of tramp and detrimental elements affecting on steel quality has been also investigated.
The results reveal improving the steel quality by increasing DRI percentage, as the tramp elements (Cu, Sn, Ni, Cr) and detrimental elements (P, S) and also nitrogen, all decrease by increasing the percentage of DRI in the metallic charge. On the other hand, the increase in DRI percentage leads to increase in the consumptions (per ton of liquid steel) of electric energy, oxygen, coke and fluxing materials. Furthermore, the metallic yield decreases and the power on time and hence the tap-to-tap time increase as DRI percentage increases. With using higher DRI percentage in the charge, the yield strength and ultimate tensile strength of produced hot rolled bars of low carbon steel slightly decrease whereas elongation increases.

Factorial design was used to investigate the contribution effect of cooling rate of stage between rolling and coiling and cooling rate after coiling on grain size, pearlite lamellar spacing, mechanical properties and hardness of hot rolled narrow 65Mn strip. The contribution of both cooling rates before and after coiling process, and the interaction combination effect of both rates were determined for each measured property. The regression models were built up to identify grain size, pearlite lamellar spacing, mechanical properties and hardness as a function in cooling rates before and after coiling process.
It was found that the contribution effect of cooling rate before coiling on grain size growth, enlargement of pearlite lamellar spacing, Ultimate Tensile Strength (UTS) and elongation is negative with different magnitude and it has positive effect on Yield Strength (YS) and hardness. Cooling rate after coiling has negative effect on grain size growth, enlargement of pealite lamellar spacing and elongation while it has positive contribution on UTS, YS, and hardness. The interaction combination effect of both two rates has very small positive contribution on YS and elongation, it has small positive effect on grain size growth, enlargement pearlite lamellar spacing, and it has large negative contribution on UTS and hardness. Factorial design technique is a successful technique to analysis the effecting parameters.

news in steel

Divestment confirmed of Ruukki Construction’s business operations in Russia

As communicated in July, SSAB has agreed to divest Ruukki Construction’s business operations in Russia (OOO Ruukki Rus) to the Russian company OAO Salavatneftemash. The transaction has received the approval of the Russian competition authorities and has now been completed. The transaction excludes the right to the Ruukki brand.

High yield strength and close tolerances

Spanish welded steel tube specialist Bornay S.L. has ordered an HF (High Frequency) tube welding line, type RD 40, from SMS group for its Alicante works. SMS group is the single-source supplier of all technical equipment from strip preparation to the cut-off-saw.

SSAB and Kemppi create a joint digi solution to speed up the welding process

SSAB and welding solutions company Kemppi have successfully piloted sending material certificates automatically from SSAB’s SmartSteel cloud to welding equipment.

Tibnor to acquire Sanistål’s steel distribution business

SSAB’s subsidiary Tibnor has agreed to acquire the steel distribution business of the Danish company Sanistål A/S, Denmark’s second largest steel distributor. This supports SSAB’s strategic target to strengthen its Nordic home market position.