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1

Achievements in micromagnetic techniques of steel plastic stage evaluation

Campos M. F. de

Advances in Materials Science

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2020

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Vol. 20, nr 1(63)

16--55

EN

The investigation of plastic deformation and residual stress by non-destructive methods is a subject of large relevance for the industry. In this article, the difference between plastic and elastic deformation is discussed, as well as their effects on magnetic measurements, as hysteresis curve and Magnetic Barkhausen Noise. The residual stress data can be obtained with magnetic measurements and also by the hole drilling method and x-ray diffraction measurements. The residual stress level obtained by these three different methods is different, because these three techniques evaluate the sample in different depths. Effects of crystallographic texture on residual stress are also discussed. The magnetoelastic term should be included in micromagnetic methods for residual stress evaluation. It is discussed how the micromagnetic energy Hamiltonian should be expressed in order to evaluate elastic deformation. Plastic deformation can be accounted in micromagnetic models as a term that increases the coercive field in soft magnetic materials as the steels are.

2

Mikrostruktura i właściwości wytrzymałościowe gwoździ wytwarzanych od początku XX wieku do chwili obecnej

Skoczylas P., Penkul A.

Inżynieria Powierzchni

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2018

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nr 3

26--32

PL

W pracy porównano mikrostrukturę, właściwości wytrzymałościowe oraz twardość gwoździ wytwarzanych w różnych okresach, od pierwszej wojny światowej do współczesności. Wśród badanych materiałów są gwoździe kute ręcznie, walcowane na gorąco oraz gwoździe współczesne wytwarzane metodą kucia matrycowego. Starsze gwoździe mają głównie trzpień o przekroju kwadratowym, natomiast najpopularniejsze gwoździe produkowane współcześnie mają trzpień okrągły. Badania wykazały, jak zmieniła się jakość stali stosowanej do ich wyrobu i jak przełożyło się to na właściwości wytrzymałościowe. Dowiedziono również, iż jakość obecnie używanych stali do wyrobu gwoździ jest dużo wyższa niż od stosowanych 80–100 lat temu. Za starszymi gwoździami przemawia natomiast kwadratowy kształt przekroju poprzecznego trzpienia, który utrudnia pękanie drewna w trakcie wbijania gwoździa, a dzięki większym wartościom współczynników wytrzymałości na zginanie i skręcania jest mniej podatny na odkształcenie.

EN

The work compares the microstructure, strength properties and hardness of nails manufactured in different times – from the First World War to the present. Among the tested materials there are hand-forged nails, hot-rolled nails and contemporary nails manufactured by die-forging. Older nails have mainly a square-shaped shank, while the most popular nails produced today have a round shank. The tests have shown how the quality of steel used for the production of nails changed and how it influenced the strength properties. It has also been proved that the quality of the steels currently used for the production of nails is much higher than of those used 80–100 years ago. The advantage of the older nails, however, is the square shape of the cross-section of the shank, which hinders cracking of wood during nail hammering, and due to the higher values of strength factors during bending and twisting, it is less susceptible to deformation.

3

Increased resistance of acicular ferrite microstructure to hydrogen embrittlement - physical metallurgy cause of this effect

Mazancová E., Slavíková I., Mazanec K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2007

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Vol. 321, z. 89

117-118

EN

The grain refinement leading to the strength and ductility increase represents important parameter resulting in improved achieved physical metallurgy properties. The acicular ferrite (AF) can be held for a promising microstructure contributing to the accomplishment of above mentioned requirement. The AF is initiated in the same temperature range as bainite (B) by the same transformation mechanism. The difference between AF and B consists in their different nucleation sites in steel matrix. In case of B the ferritic grains are nucleated at the austenite (A) grain boundaries. On the contrary, AF plates are nucleated on non-metallic particles which fulfil special conditions of their nucleability. The AF particles exhibit different orientations in the formation of the fine grained interlocking morphology. The bainitic packets consist of parallel plates (laths) having low angle interface orientations. The beneficial mechanical properties of the AF microstructure are related to the high frequency of high angle interfaces acting as effective obstacles to cleavage cracks propagation in contradistinction to the weak influence of the B having low angle plates interfaces. In B, only packets show high angle boundaries what results in larger free path for cleavage crack propagation [1]. The above discussed beneficial AF properties are acting in large scope inclusive of improved resistance of steels to hydrogen induced cracking. The fracture process analysis has shown the strength and toughness behaviour of AF microstructure are different from that conventional microstructure by reason of its particular microstructure characteristics. In the AF microstructures, the density of micro-orientated plates is enhanced by a profused direct intragranular nucleation on non-metallic inclusions. In the bainitic microstructure a decisive role is ascribed to morphological packets representing the microstructure unit that controls the cleavage cracks propagation without their deflecting. In the B microstructure, the morphological packets size (de) is related to the dimension of unit crack path (UCP) corresponding to the distance between neighbouring high angle boundaries [2]. The AF analysis shows, the microstructure unit is directly related to the set of the AF plates having high angle interface, what is corresponding to the unit crack path in the AF microstructure. In the AF, this value is shorter in comparison to the dimension of packets in investigated B. In the AF, it is 4-5 jim while in the B this distance is substantially greater and attains up to 20jam, approximately. Using the UCP value - dB, it is possible to determine the transition behaviour in steel T = To - K.dB"1/2, where K represents constant value, To depends on the tensile strength. Above presented equation shows, the transition temperature is universally proportional to the square root of distance between high angle interfaces. The AF makes the crack propagation difficult due to presence of a great number of high angle interfaces. The presented AF microstructure is stable and is kept after hydrogen charging process. The increased deflection numbers of the AF plates contribute to the achievement of high resistance to hydrogen induced cracking in this microstructure. The positive AF properties on the resistance to hydrogen induced cracking and the SSC formation in oil and gas pipe-line steels (X60-X80) confirm above presented idea [3]. The investigated steel with dominating AF microstructure, having optimum mechanical properties consists of the fine non-equiaxed and interwoven ferritic plates containing the ultra-fine carbonitrides, eventually. In some case the formed small M/A islands are not excluded absolutely. The AF plates formed by displacive transformation mechanism contain increased dislocation densitiy. This substructure contributes to the trapping of hydrogen atoms and in this way limits the detrimental hydrogen effect on steel properties. The combination of increased resistance to cleavage crack propagation and partial limitation of hydrogen activity (due to dislocation trapping of hydrogen atoms) result in the improvement of steel properties. These results demonstrate, the AF microstructure represents a perspective way how to increase steel durability under simultaneous hydrogen action.

4

Contribution to the Modelling of Processes Controlling the Acicular Ferrite (AF) Formation in C-Mn Steels

Mazancová E., Jonšta Z., Mazanec K.

Machine Dynamics Problems

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2006

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Vol. 30, No. 4

60-67

EN

Due to special morphology, AF microstructure makes possible to obtain a very favourable combination of mechanical properties (strength, ductility and toughness). The significant parameter is the deflection mechanism limiting cleavage crack propagation. Although the nucleation role of fine special non-metallic inclusions as inoculants controlling the austenite (A)-decomposition into ferrite has been described in great number of works, the comprehensive mechanism of these processes has not been developed. Due to large variety of non-metallic particles acting as inoculants in above considered transformation process, this solution is not facile. The nucleation potency of individual phases comprising complex inclusions has not been assessed so far. In the present contribution the investigation will be devoted to the finding of model being able to describe the nucleating behaviour of some complex inclusions based on manganese - silicate (MnO-SiO2) and on the nucleating effect of Mg-addition (MgO) to the basic chemical constitution resulting from deoxidization with Mn/Si/Ti. Among considered mechanism as the most perspective one could be held the formation of Mn-depleted zone being the nucleation site for intragranular A-decomposition into ferrite phase. It has been proposed this zone is formed around inclusion by the subsequent MnS nucleation on it. This process is accompanied with the subsequent Mn-diffusion running in the steel matrix to the MnS-nuclei. The following conclusions can be determined from the achieved results in investigated steel types. The nucleation potency of some inclusions complex represents a decisive initiation parameter in decomposition of A into AF. It has been established the higher density number of dispersed fine intragranular particles (0.5-2.0 µm) is very effective in the refinement of ferrite plates by AF nucleation. The non-metallic inclusions type participating in the considered nucleation process is determined by steel deoxidization. Precipitation of MnS on primary inclusions (investigated influence of Mn/Si and Mn/Si/Ti) has been analyzed. For both examples the same physical metallurgical characteristics leading to the formation of Mn-depleted zone and simultaneously realized MnS nucleation on applied non-metallic inclusions have been found. In case of AF nucleation on inclusions after Mg addition the mechanism of Mn-depleted zone has been also confirmed. The mechanism of AF formation in connection with Mn-depleted zone existence around the primary steel inclusions accompanied with MnS formation has been analyzed in detail. This complex mechanism can be considered as a very attractive model making possible to predict the AF nucleability in austenitic matrix.

5

Zastosowania DSC

Sierpiński Z.

LAB Laboratoria, Aparatura, Badania

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2006

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R. 11, nr 5

6-10

6

Analiza termomechaniczna TMA

Sierpiński Z.

LAB Laboratoria, Aparatura, Badania

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2006

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R. 11, nr 6

23-26

7

Metaloznawstwo wczoraj i dziś

Maciejny A.

Hutnik, Wiadomości Hutnicze

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2004

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Vol. 71, nr 12

576-583

PL

W pracy przedstawiono kształtowanie się wiedzy metaloznawczej do metalografii do metaloznawstwa oraz nauki o materiałach i inżynierii materiałowej. Omówiono znaczenie dla tego procesu kolejnych odkryć naukowych, rozwoju metod badawczych oraz postępu technicznego i cywilizacyjnego. Podkreślono rolę badań żelaza i jego stopów w rozwoju metaloznawstwa. Przedstawiono problematykę współczesnego metaloznawstwa jako trzonu nauki o materiałach i inżynierii materiałowej.

EN

The work presents formation of physical metallurgy knowledge commencing from the metallography to metal and materials science and engineering. Importance of the successive science discoveries, development of the research methods as well as technological and civilization progress to this process has been discussed. A vital role of iron and ferroalloys in development of physical metallurgy has been emphasized. Problems of the modern physical metallurgy as an essential constiuent of the materials science and engineering have been presented.

8

Contribution to the Physical Metallurgy of Acicular Ferrite

Mazancová E., Jonšta Z., Wyslych P., Mazanec K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2003

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z. 76

121-126

9

Contribution to physical metallurgy of hot ductility behaviour of steels

Pavliska J., Jonšta Z., Mazanec K., Mazancová E.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2001

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Vol. 279, z. 72

55-58

10

Physical metallurgy and modelling of theromomechanically processed microalloyed steels.

Siwecki T.

Inżynieria Materiałowa

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1998

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R. XIX, nr 3

163-170

EN

The effects of thermo-mechanical controlled processes (TMCP) followed by accelerated cooling (ACC) or direct quenching (DQ) and their parameters are discussed in relation to the microstructure (development) and mechanical properties of high strength steels, microalloyed with Ti, V, (Mo) and/or Nb. Computer models for calculation of microstructure evolution (grain size, grain growth, precipitation and flow stress) during heavy plate, strip and long product hot rolling are invaluable for design of TMCP-rolling schedules combining a maximum degree of microstructure refinement with acceptably low rolling loads. Intelligent design of deformation/temperature schedules aims to generate an optimal austenite microstructure and subsequently a fine ferrite/bainite conferring both taughness and strength. A comparison is made of the results of laboratory simulations with full scale industrial plate, strip and long product processing using TMCP practices obtained at various (high and low) finish rolling temperatures with and without application of accelerated cooling/direct quenching.