The factorial design approach can be used to precisely estimate the effect of different parameters on the reduction process of iron oxide. In the current study, a 24 factorial design was used to significantly calculate the magnitude impact of manganese oxide and silica on the reduction yield of iron oxide which was reduced with H2 at 900-1100°C. A regression model was built on the experimental reduction results of pure iron oxide and iron oxide doped with either MnO2 (mass content of 6%) and/or SiO2 (mass content of 7.5%) at 900°C and 1100°C. The developed mathematical model was used to predict the reduction yield as a function of four parameters including MnO2 (mass content of 0-6%), SiO2 (mass content of 0-7.5%), reduction time (1.0-10 min) and temperature (900-1100°C). In addition, the effect of the interaction combination of different parameters (MnO2, SiO2, time, and temperature) on the reduction yield was estimated. The results showed that the reduction time has the highest positive effect on the reduction yield of iron oxide sinter followed by the applied temperature and then SiO2 addition. On the other hand, MnO2 exhibited the highest negative effect on the reduction yield of iron oxide followed by the combination effect of SiO2 with time and temperature. The interaction combination effect of MnO2 with temperature or MnO2-SiO2 with time and temperature on the reduction yield was very small. The regression model was applied to theoretically estimate the reduction yield of pure and doped iron oxide at 900-1100°C. The obtained values of the derived model are in a good agreement with the experimental results under different conditions.

In the last two decades, the significant market demands for microalloyed steels have led to enormous efforts as regards the optimization of their properties. Following a national research program, the present work was scheduled to deal with a special grade of V-microalloyed steel. This grade was examined after a series of successive isothermal heat treatment to produce a variety of phase combinations (e.g., ferritic-martensitic, ferritic-martensitic-bainitic and ferritic-bainitic microstructures). Tensile and impact tests were performed to gain knowledge about the mechanical properties. The resulting microstructures were evaluated by means of SEM and optical microscopy. The results indicated that the corresponding tensile behaviour of the steels was strongly affected by microstructure and heat treatment parameters. Furthermore, the related ultimate tensile strength and impact values were broadly varied (750 to 1200 MPa and 5 J to 40 J, respectively) by the steels´ microstructure and chemical composition. The corresponding fracture surfaces were found to vary with the steel´s microstructure.

The influence of accelerated cooling and coiling temperature is studied in a microalloyed steel grade in order to investigate the strengthening owing to phase transformation in the presence of microalloying elements. A Nb-V microalloyed steel grade was deformed in the austenitic range followed by controlled quenching to simulate rolling and runout table cooling conditions. Cooling rate was varied from 100 to 150 °C/sec, while coiling temperatures were varied between 475 to 625 °C, with 25 °C step. Decrease in transformation temperature in conjunction with accelerated cooling resulted in non-equiaxed ferrite structures with array of phase morphologies. Intermediate transformation temperatures produced increase in strength concurrent with observed peak broadening in X-ray diffraction. In addition, microstructural modelling is done using Quench properties module of JMatPro under experimental conditions.

Dry sliding adhesive wear behaviour of as-cast and austempered ductile iron (ADI) samples alloyed with manganese and copper was investigated in a pin-on-disc wear testing machine. As-cast samples suffered a rapid and continuous wear, while the austempered samples exhibited improved wear resistance on increasing the austempering temperature and time. ADI samples with higher copper plus manganese contents inherently possessed higher hardness due to presence of martensite in the ausferrite matrix. The wear conditions used in the present
study further promoted the formation of martensite under wear load and contributed much improved wear performance. In ADIs containing manganese only, wear process involved a mixed mechanism of oxidation and delamination. On combined alloying with copper and manganese, wear resistance increased considerably showing only mild oxidation and practically no delamination. The combinedly alloyed austempered samples exhibited even better wear resistance than that of cast and heat treated high manganese steel. Thus, the addition of manganese and copper in the experimental ductile irons assisted austempering by virtue of their synergistic effect on hardenability of Fe-C alloys and improving wear resistance through subsequent work hardening of the wear surface.

Steel enjoys an unsurpassed wide range of properties: first of all its stiffness-strength-formability relationship contributes to featuring steel a high potential as versatile light-weight construction material. In this respect it pays to use steel, its price cannot be undercut without accepting compromises. This is topped by additional gains comprising high availability, reliability, excellent manufacturability and recyclability. Steel enjoys great popularity amongst designers, most of them are very familiar with it. In intermaterial competition, steel may not win in every single discipline, but steel is the undisputed champion in multi-discipline jobs. This makes steel an indispensable material.

news in steel

SCHMOLZ + BICKENBACH and TSINGSHAN to form Joint Venture in China

SCHMOLZ + BICKENBACH, a global leader in special long steel, and TSINGSHAN GROUP ("TSINGSHAN"), a world leader in stainless steel, today announced the formation of a Joint Venture ("JV") in China. The JV company is 60 percent owned by SCHMOLZ + BICKENBACH and 40 percent by TSINGSHAN and will operate under the name Shanghai Xinzhen Precision Bar Co. Ltd. out of Shanghai (China).

SSAB invests in carbon-dioxide-free internal transport

SSAB in Oxelösund, TFK Transport Research Institute and Kalmar, a part of Cargotec, are to initiate a unique multimillion-SEK project to develop and test carbon-dioxide-free internal transport powered by hydrogen and fuel cells.

Longer service life and improved arc focusing: the world’s first electrode developed especially for aluminium welding

Even though the processing of aluminium is very different from other metals and, for example, the correct welding temperature has to be maintained with especially high precision, there has not been an electrode to date designed especially for this field of application.

SSAB EcoUpgraded for significant CO2 savings

A global sustainability initiative from SSAB is helping customers reap the environmental rewards of using high-strength steel. SSAB EcoUpgraded is highlighting the benefits of upgrading to high-strength steel, which include reduced weight, improved fuel economy and extended product lifetime.