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1

Effect of Cr, Mo and Al on Structure and Selected Mechanical Properties of Austenitic Cast Iron

Medyński D., Janus A.

Archives of Foundry Engineering

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2019

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iss. 4

39--44

EN

Results of a research on influence of chromium, molybdenum and aluminium on structure and selected mechanical properties of Ni-Mn- Cu cast iron in the as-cast and heat-treated conditions are presented. All raw castings showed austenitic matrix with relatively low hardness, making the material machinable. Additions of chromium and molybdenum resulted in higher inclination to hard spots. However, a small addition of aluminium slightly limited this tendency. Heat treatment consisting in soaking the castings at 500 °C for 4 h resulted in partial transformation of austenite to acicular, carbon-supersaturated ferrite, similar to the bainitic ferrite. A degree of this transformation depended not only on the nickel equivalent value (its lower value resulted in higher transformation degree), but also on concentrations of Cr and Mo (transformation degree increased with increasing total concentration of both elements). The castings with the highest hard spots degree showed the highest hardness, while hardness increase, caused by heat treatment, was the largest in the castings with the highest austenite transformation degree. Addition of Cr and Mo resulted in lower thermodynamic stability of austenite, so it appeared a favourable solution. For this reason, the castings containing the highest total amount of Cr and Mo with an addition of 0.4% Al (to reduce hard spots tendency) showed the highest tensile strength.

2

Effect of nanoparticles on the structure and properties of welds made of high strength low-alloy steels

Grigorenko G. M., Kostin W. A., Gołowko W. W., Żukow W. W.

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2016

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Vol. 60, No. 6

64--69

PL

Przedstawiono wyniki badań struktury metalu spoin wysokowytrzymałej niskostopowej stali 14HGNDC, do roztopionego materiału której wprowadzano nanoproszkowe cząstki różnych związków trudno topliwych - tlenków, węglików i azotków (TiC, TiN, SiC, VC, NbC, TiO2, Al2O3, MgO, ZrO2). Przeprowadzone badania wykazały efektywność zastosowania nanotlenków tytanu TiO2 i cyrkonu ZrO2, co pozwoliło zapewnić wysokie wartości własności mechanicznych metalu spoin (Rm -708 MPa i 621 MPa, KCV-20- 60 J/cm2 i 72,9 J/cm2, a - 21 i 19%). Zastosowanie symulatora cykli cieplnych Gleeble 3800 pozwoliło na ustalenie zależności między temperaturowymi zakresami przemian, ilością składników strukturalnych i typem modyfikujących nanocząstek.

EN

The article presents test results concerning the structure of welds made of high strength low-alloy steel 14HGNDC which, in the molten state, was provided with nanoparticles of various refractory compounds including oxides, carbides and nitrides (TiC, TiN, SiC, VC, NbC, TiO2, Al2O3, MgO, ZrO2). The performed tests revealed the effective use of the nano-oxides of titanium (TiO2) and zirconium (ZrO2) enabling the obtainment of high mechanical properties of the weld metal Rm -708 MPa and 621 MPa, KCV-20 - 60 J/cm2 and 72,9 J/cm2, a - 21 and 19%). The use of a Gleeble 3800 welding cycle simulator made it possible to determine the dependence between temperature ranges of transformations, amount of structural constituents and types of modifying nanoparticles.

3

Heat treatment of Ni–Mn–Cu cast iron

Janus A., Granat K.

Archives of Civil and Mechanical Engineering

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2014

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Vol. 14, no. 4

602--607

EN

Examined was the influence of chemical composition defined by the nickel equivalent, as well as time and temperature of soaking on course of decomposition process of metallic matrix in the austenitic Ni–Mn–Cu cast iron. In alloys with the equivalent value ranging from 16.0% to 23.0%, with properly selected heat-treatment parameters, possible is controlled, partial transition of austenite to hard acicular ferrite. Obtained is the structure morphologically corresponding to that of ausferrite, characteristic for cast iron quench-hardened with isothermal transformation (e.g. CGI or ADI). Replacing the quench-hardening operation by soaking permits, among others, obtaining homogeneous structure in the entire cross-section of solid thick-walled castings or elimination of quenching stresses.