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1

Effect of various factors on the measurement error of structural components of machine parts materials microhardness using computer vision methods

Vlasovets Vitaliy, Vlasenko Tatiana, Kovalyshyn Stepan, Kovalyshyn Olesy, Kovalyshyn Oleg, Kurpaska Sławomir, Kiełbasa Paweł, Bilovod Oleksandra, Shulga Lyudmila

Przegląd Elektrotechniczny

|

2023

|

R. 99, nr 1

323--329

EN

To assess the causes of failure of parts in operation, it is often necessary to assess the degradation of the structural and phase composition of the material and determine the cause of its change. Microhardness test is used to evaluate the mechanical properties of microvolumes of the material. Microhardness of structural components of steels and cast irons (armco iron ferrite, austenitic component of steel 12Х18Н10Т and cementite of centrifugally cast chrome-nickel cast iron (cast coating Ø910 mm)) was determined by restored four-sided pyramid impression with a square base and a top angle of 136±1. The paper evaluates the influence of the main factors on the micro-hardness error of ferritic, austenitic and carbide component of steels and cast irons: the amount and speed of the indenter load, the stiffness of the substrate, the field of distribution of plastic deformations around the impression, the quality of the surface preparation, the influence of grain boundaries and the relaxation of the impression shape over time. The main factors affecting the accuracy of measurements by the reconstructed impression method have been determined for each of the investigated phases: ferrite, austenite, and cementite.

PL

Aby ocenić przyczyny awarii części w eksploatacji, często konieczna jest ocena degradacji składu strukturalnego i fazowego materiału oraz określenie przyczyny jego zmiany. Do oceny właściwości mechanicznych mikroobjętości materiału stosuje się test mi-rotwardości. Mikrotwardość składników strukturalnych stali i żeliwa (ferryt żelaza armco, austenityczny składnik stali 12Х18Н10Т i cementyt odśrodkowo odlewanego żeliwa chromowo-niklowego (powłoka odlewu Ø910 mm)) określono przez przywrócony wycisk piramidy czterobocznej o podstawie kwadratowej i kącie wierzchołkowym 136±1. W pracy oceniono wpływ głównych czynników na błąd mikrotwardości ferrytycznego, austenitycznego i węglikowego składnika stali i żeliwa: wielkości i prędkości obciążenia wgłębnika, sztywności podłoża, pola rozkładu odkształceń plastycznych wokół wycisku, jakości przygotowania powierzchni, wpływu granic ziaren oraz relaksacji kształtu wycisku w czasie. Określono główne czynniki wpływające na dokładność pomiarów metodą zrekonstruowanego wycisku dla każdej z badanych faz: ferrytu, austenitu i cementytu.

2

Wpływ modyfikacji technologii wytwarzania drutów kordowych na ich właściwości mechaniczne i technologiczne

Grygier Dominika

Hutnik, Wiadomości Hutnicze

|

2022

|

Vol. 89, nr 1

20--25

PL

Stale perlityczne zawierające, od około 0,70 do 0,95% C, należą do grupy stali niestopowych, klasy jakościowej przeznaczonej do ciągnienia lub walcowania na zimno. Znalazły one zastosowanie głównie jako druty przeznaczone do produkcji stalowego kordu wzmacniającego opony samochodowe, gąsienice elastomerowe, taśmy przenośnikowe oraz węże ciśnieniowe. Niestety, jednym z poważnych problemów, szeroko opisywanych w literaturze, jest ich pękanie następujące podczas eksploatacji. Głównym celem badań prezentowanych w pracy było opracowanie zasad oraz weryfikacja eksperymentalna metody wytwarzania struktur sferoidalnych w stalach perlitycznych. Ideą wytworzenia tych struktur była możliwość uzyskania unikatowego zespołu wysokich właściwości mechanicznych oraz plastycznych tej grupy materiałów, a tym samym poprawa właściwości użytkowych, w szczególności odporności na pękanie. Te zalety mogą sprawić, że stale perlityczne mogłyby być wykorzystane w przemyśle maszynowym, lotniczym i zbrojeniowym, gdzie jednymi z ważniejszych parametrów są niezawodność i bezpieczeństwo eksploatacji.

EN

The pearlitic steels containing from about 0,70 to 0,95% of C belong to the group of unalloyed steels of the quality class intended for cold drawing or rolling. They have found application mainly as wires for production of steel cord reinforcing car tires, elastomeric tracks, conveyor belts and pressure hoses. Unfortunately, one of the serious problems widely discussed in the subject literature is their cracking during operation. The main purpose of the research presented in the work was development of the principles and the experimental verification of the method of creating spheroid structures in pearlitic steels. The concept of creating the this structure was related to the possibility of obtaining the unique set of high mechanical and plastic properties of that material group, and thus the improvement of their performance, and the crack resistance in particular. These advantages can make the pearlitic steels could be used in the machine, aerospace and armaments industries, where one of the important parameters are the reliability and operation safety.

3

Characteristics of Ledeburite in EDS Analyses of Directionally Solidified Eutectic White Cast Iron

Trepczyńska-Łent Małgorzata, Seyda J.

Archives of Foundry Engineering

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2022

|

Vol. 22, iss. 4

65--71

EN

The paper addresses the microsegregation of Mn, Mo, Cr, W, V, Si, Al, Cu and P in the white cast iron. Eutectic alloy with the content of 4.25% C was studied. The white cast iron was directionally solidified in the vacuum Bridgman-type furnace at a constant pulling rate v=83 μm/s and v=167 μm/s and at a constant temperature gradient G = 33.5 K/mm. The microstructural research was conducted using light and scanning electron microscopy. The microsegregation of elements in ledeburite was evaluated by EDS measurements. Content of elements in ledeburitic cementite and ledeburitic pearlite was determined. The tendency of elements to microsegregation was found dependent on the solidification rate. Microsegregation of elements between pearlite and cementite structural constituents has been specified. The effect of solidification rate on the type and intensity of microsegregation in directionally solidified eutectic white cast iron was observed. A different type of microsegregation was observed in the components of ledeburite in cementite and pearlite.

4

Influence of plastic deformation carbon steel on the process of burning electric arc

Vakulenko Igor Alex, Plitchenko Sergey, Kurt Bulent, Askerov Hangardas, Proydak Svetlana, Erdogdu Ahmet Emrah

Zeszyty Naukowe. Transport / Politechnika Śląska

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2021

|

z. 112

211--218

EN

During a study of the combustion process of a direct polarity electric arc, a directly proportional dependence of the electric current value on the degree of cold plastic deformation of carbon steel used as an electrode was found. To calculate the value of the electric current during arc burning, in the indicated ratio, it was proposed to replace the surface tension force of the liquid metal with the surface tension of ferrite of plastically deformed carbon steel. Calculation of the ferrite’s surface tension value on the deformation degree of the steel under study through the size of the coherent scattering regions was used to explain the observed dependence of the electric current during arc burning. From the analysis of the considered correlation ratios, it was found that with an increase in the cold deformation degree, the refinement of the coherent scattering regions results in the ferrite’s surface tension increase and consequently, to an increase in the electric current during arc burning. Comparative analysis of the obtained results of calculating the value of electric current during arc burning through the surface tension of ferrite of cold-deformed carbon steel showed a fairly good coincidence with experimental data. The differences did not exceed 9%.

5

Decomposition mechanisms of continuously cooled bainitic rail in the critical heat-affected zone of a flash-butt welded joints

Królicka Aleksandra, Żak Andrzej, Kuziak Roman, Radwański Krzysztof, Ambroziak Andrzej

Materials Science Poland

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2021

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Vol. 39, No. 4

615--625

EN

The joining process of bainitic rails is significant in terms of their industrialization in high-speed and heavy-loaded railways. This paper demonstrates the microstructure changes in the critical zone of the welded joint, which is responsible for the greatest deterioration in mechanical properties. Extensive progress in the decomposition of the retained austenite and bainitic ferrite occurs in the low-temperature heat-affected zone (LTHAZ) of the flash-butt welded joint of low-carbon bainitic rail. The decomposition products of the retained austenite were mainly a mixture of cementite and ferrite. The cementite was mainly precipitated at the boundary of the bainitic ferrite laths, which indicates lower thermal stability of the filmy austenite. Moreover, it was found that a part of the refined blocky retained austenite was decomposed into the ferrite and nanometric cementite, while another remained in the structure. The decomposition mechanisms are rather heterogeneous with varying degrees of decomposition. A relatively high proportion of dislocations and stress fields prove the occurrence of residual stresses formed during the welding process.

6

An Investigation on Divorced Eutectoid Growth of Cementite in Eutectoid Steel

Biswas Prasenjit, Maity Joydeep

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 3

1171--1176

EN

Divorced eutectoid growth of cementite in AISI 1080 steel is investigated as a function of cooling rate for incomplete austenitization-based heat treatment. Furthermore, a fundamental mathematical relationship is established through analytical treatment that correlates divorced eutectoid growth with effective cooling rate and degree of undercooling in view of bulk diffusion controlled growth model. As the cooling rate increases, the divorced eutectoid growth of cementite is gradually ceased. The result predicted by the analytical model closely matches with the experimental result (%Deviation ≤ 7).

7

Preconditiong and Inoculation of Low Sulphur Grey Iron

Hossain Md Sojib S., Bazlur B. Rashid A. K. M.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 1

61--66

EN

For quality grey cast iron production, the challenging issues are to avoid cementite structure and obtain the desired graphite morphology with proper matrix as well as hardness. The objective of the present research is to find out the right combination of preconditioner and inoculant that may help to overcome the challenges. In this work, sulphur content is kept low (0.01%). Two preconditioners namely metallurgical SiC and zirconium bearing FeSi with two types of inoculant are individually used to make four combinations of sample and for each case metal is poured into the green sand mould. Finally Brinell hardness and graphite morphology is observed in the thickest and thinnest portions of the castings. Metallurgical SiC with barium bearing inoculant gives better graphite morphology and hardness than strontium bearing inoculant, on the other hand zirconium bearing FeSi gives more satisfying result than SiC with every type of inoculant. Among all of the combinations Zr bearing preconditioner with Ba bearing inoculant gives good graphite morphology with best mechanical properties in both thickest and thinnest portions of the casting.

8

Peculiarities of Alloying Effect on the Eutectic Cementite Behavior Under Hot Rolling

Mironova Tatiana, Proidak Svetlana

New Trends in Production Engineering

|

2019

|

Vol. 2, Iss. 2

289-300

EN

Currently, cast iron remains one of the major modern casting materials in metallurgy and machine-building industry and is sure to take the lead in the future. Chilled cast iron has high hardness and wear resistance due to a large number of carbide phases in its structure. However, low ductility and impact hardness essentially limit its applicability in terms of processing. Hot plastic working, under which the eutectic net crushing is observed, appears to be one of the most effective means of the eutectic alloy products shape and microstructure transformation. Chilled cast iron properties fundamentally improve after hot plastic working: ductility, strength and impact hardness increase by 2-3 times on retention of the high hardness factor. Chilled cast iron ductility increase can be attained when using phase transformations in eutectic cementite under lean alloying with carbide forming elements. The purpose of the paper is to study alloying effect on the chilled cast iron ductility as well as eutectic cementite behavior under hot rolling. In the paper hardening and softening of the structural components in chilled cast iron under hot working have been studied. The deformation texture forming in eutectic cementite under hot rolling has been revealed, which is connected with the dynamic softening and depends on the degree and the nature of its alloying. The mechanism and regularities of the phase transformation effect in cementite on its behavior under plastic deformation and on the alloys ductility in general have been studied. In cementite chromium alloying initiates processes, that can be characterized as the pre-precipitation stage of the new phases, and this way it contributes to the cast iron ductility reduction and embrittles cementite. Carbide transformation, that occurs in eutectic cementite under alloying with vanadium, stimulates softening of the alloy and increases its ductility level. Moreover, the multiple glide planes {130},{011},{112} in cementite have been determined. It has been found out, that in supersaturated cementite vanadium carbides precipitation stimulates the extra glide plane {111} occurrence under hot rolling. The essence of the carbide transformation phenomenon is that under hot working there occurs the lubricating effect at the transition of the metastable iron carbide condition, which is strengthened with vanadium supersaturation and mechanical hardening, to a more stable condition due to precipitation of the proeutectoid constituents on the one hand, and because of the dynamic softening processes on the other hand. At that, the autocatalyticity effect is observed: there is precipitation of carbides with hardening and softening, similar to the processes that arise as a result of the superplastic effect induced by phase transformations.

9

The Role of Microstructure in High Temperature Tribology of Iron Alloys

Krawczyk J., Rożniata E., Zimowski S., Kot M., Dąbrowski R., Dziurka R., Frocisz Ł.

Archives of Metallurgy and Materials

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2018

|

Vol. 63, iss. 2

915--920

EN

The present paper describe the issue of tool materials wear in a high temperature conditions. The investigations were performed at the cast steel tool material at the tribological contact to the structural steel. The investigations aim was to determine the role of microstructure in a tribological properties between the structural steel and tool material. The results of such investigation could be referenced to the industry conditions and could answer about the problems of tool materials wear. The observations of the wear mechanisms were referred to the microstructure of the mill rolls. The laboratory tests ware aimed at evaluating the thermal treatment modification effect on the cast steels properties. A significant role of the morphology of ledeburitic cementite and secondary cementite on the tribological properties was exhibited. The investigations assumed the presence of an austenitic matrix with primary and secondary cementite. Influence of varying morphology carbides was described. in the cast steel microstructure. The investigation results make possible to point to a direction of carbide morphology change with the purpose of obtaining the assumed properties of hot operation tools.

10

Wpływ modyfikacji technologii wytwarzania drutów kordowych na ich właściwości mechaniczne i technologiczne

Grygier A.

Przegląd Mechaniczny

|

2017

|

nr 11

48--53

PL

Stale perlityczne zawierające, od około 0,70 do 0,95% C, należą do grupy stali niestopowych, klasy jakościowej przeznaczonej do ciągnienia lub walcowania na zimno. Znalazły one zastosowanie głównie jako druty przeznaczone do produkcji stalowego kordu wzmacniającego opony samochodowe, gąsienice elastomerowe, taśmy przenośnikowe oraz węże ciśnieniowe. Niestety, jednym z poważnych problemów, szeroko opisywanych w literaturze, jest ich pękanie następujące podczas eksploatacji. Głównym celem badań prezentowanych w pracy było opracowanie zasad oraz weryfikacja eksperymentalna metody wytwarzania struktur sferoidalnych w stalach perlitycznych. Ideą wytworzenia tych struktur była możliwość uzyskania unikatowego zespołu wysokich właściwości mechanicznych oraz plastycznych tej grupy materiałów, a tym samym poprawa właściwości użytkowych, w szczególności odporności na pękanie. Te zalety mogą sprawić, że stale perlityczne mogłyby być wykorzystane w przemyśle maszynowym, lotniczym i zbrojeniowym, gdzie jednymi z ważniejszych parametrów są niezawodność i bezpieczeństwo eksploatacji.

EN

The pearlitic steels containing from about 0,70 to 0,95% of C belong to the group of unalloyed steels of the quality class intended for cold drawing or rolling. They have found application mainly as wires for production of steel cord reinforcing car tires, elastomeric tracks, conveyor belts and pressure hoses. Unfortunately, one of the serious problems widely discussed in the subject literature is their cracking during operation. The main purpose of the research presented in the work was development of the principles and the experimental verification of the method of creating spheroid structures in pearlitic steels. The concept of creating the this structure was related to the possibility of obtaining the unique set of high mechanical and plastic properties of that material group, and thus the improvement of their performance, and the crack resistance in particular. These advantages can make the pearlitic steels could be used in the machine, aerospace and armaments industries, where one of the important parameters are the reliability and operation safety.

11

Modification of Heat Treatment Parameters for Pearlite Steel Intended for Cold Plastic Working

Grygier D.

Journal of Machine Engineering

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2016

|

Vol. 16, No. 2

44--51

EN

One of the problems widely discussed in the relevant literature is the fatigue cracking of pearlite steel subjected to cold plastic working, as well as of that being currently in operation. Studies presented in the work were aimed at selection of the parameters, and mainly the time, of heat treatment operations of pearlite steel enabling obtaining cold drawn wires characterised with better plastic properties and higher fatigue resistance than the products achieved during standard processes. The idea of modification was based at possibility of obtaining steel of the sorbite, which are a mixture of ferrite and dispersion cementite of high degree of coagulation. The structures obtained with this method, as being globular, should be featured with better plastic properties than the lamellar structures created during standard diffusion transformation of austenite. In addition the discussed change was to enable decreasing the total surface of interphase boundaries at which the highest delaminations of structure were observed, regardless of whether the cause of the change resulted from presence of non-metallic inclusions or pile-up of dislocations.

12

Analysis of the causes of damage to the wires of the steel belt of car tires

Grygier D.

Interdisciplinary Journal of Engineering Sciences

|

2016

|

Vol. 4, no. 1

45--49

EN

The main when buying car tires we would like them to serve us as long as possible while the experts recommend their replacement after six years at the latest – is it really necessary? In this work the analysis of the impact of car tires operation on microstructure of the steel belt wires has been presented. The results of the presented research have proven that as a result of the complex stresses in the belt wire material the transverse cracks of individual cementite lamellae appear. The observed structural changes are a major cause of fatigue cracks development and finally result in breaking continuity of steel belt wires, breakthrough of the rubber layer and eventually damage to the tires, preventing their further work.

13

The Structural and Strength Changes Resulting from Modification of Heat Treatment of High Carbon Steel

Grygier D., Rutkowska-Gorczyca M., Jasiński R., Dudziński W.

Archives of Metallurgy and Materials

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2016

|

Vol. 61, iss. 2B

971--976

EN

Pearlitic steels containing from some 0,8 to 0,95% C belong to the group of unalloyed steels intended for cold drawing or rolling. One of the problems discussed in literature is cracking of pearlitic steel subjected to plastic working, caused by high brittleness of the lamellar precipitations of hard cementite. This issue is extremely important because it affects significantly reduce fatigue strength. The paper presents proposals to modify the process of heat treatment, results in getting a steel with spheroidal structure characterized by better plastic properties, in order to eliminate this problem.

14

The Effect of a Change in Recrystallization Annealing Time on the Properties and Structure of Cold-Drawn Wires

Grygier D., Rutkowska-Gorczyca M., Dudziński M.

Journal of Machine Engineering

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2015

|

Vol. 15, No. 1

90--97

EN

Although many heat treatment schemes have been developed for pearlitic steel, in the literature there is still little information about the influence of the different heat treatment parameters on the percentage, properties and morphology of the phases. Neither there is any information on matching the parameters, taking into account the different degree of deformation of the steel wires, the particular applications and operating conditions of the products. The aim of this research was to optimize the parameters of the interoperation annealing used during the cold plastic work-ing of pearlitic steel intended for cold-drawn wires. The results of the hardness measurements and microscopic observations, presented in this paper clearly show that there is no need to apply long recrystallization treatments to small diameter wires. This finding is highly significant from the economic point of view and it clearly shows the importance of the individual matching of heat treatment parameters to specific industrial applications.

15

The effectiveness of spheroidization pearlitic steel with regard to the degree of plastic deformation

Grygiel D., Dudziński W, Gerstein G., Nürnberger F.

Interdisciplinary Journal of Engineering Sciences

|

2015

|

Vol. 3, no. 1

6--9

EN

Pearlitic steels containing from some 0,8 to 0,95% C belong to the group of unalloyed steels of the quality class destined for cold drawing or rolling, they find application mainly as wires used for reinforcement of tires, hoses or rope production. However this group of steels characterized low machinability, as a consequence of presence hard plates of cementite, the intervention ameliorative this property is spheroidizing annealing. The object of the tests presented in paper was wires of pearlitic steel obtained after the successive stages of cold plastic working. The aim of the tests was to show that the condition of the material and mainly degree of plastic deformation have a clearly influence on the effectiveness of pearlitic steel spheroidization.

16

The effectiveness of recrystallization high carbon steel with regard to the condition of material

Grygier D.

Interdisciplinary Journal of Engineering Sciences

|

2015

|

Vol. 3, no. 1

20--24

EN

The main aim of the studies presented in paper was to optimize the parameters of the recrystallisation annealing process used in the course of cold plastic working of high carbon steel for patented wires. Object of the research described in the work was eutectoid steel of 0,8% content of C designated for production of colddrawn wires applied for reinforcement of car tires, hoses and ropes. The results of tests show that the condition of the material and mainly degree of plastic deformation has a clearly influence on the effectiveness of pearlitic steel recrystallisation.

17

Półprzemysłowa instalacja do przyśpieszonego, kontrolowanego chłodzenia stalowych wyrobów kształtowych dla projektowania przemysłowych technologii umacniania cieplnego

Kuziak R, Molenda R., Głowacki P.

Prace Instytutu Metalurgii Żelaza

|

2014

|

T. 66, nr 4

2--9

PL

W artykule przedstawiono charakterystykę techniczną półprzemysłowej instalacji do przyspieszonego chłodzenia stalowych wyrobów kształtowych. Skuteczność funkcjonowania stanowiska sprawdzono w procesie umacniania cieplnego kształtownika górniczego V-29 i szyny kolejowej typu UIC60.

EN

This article presents technical characteristics of semi-industrial installation for accelerated cooling of steel shapes. The efficiency of the workstation was checked during the heat treatment of the mining section V-29 and the railway rail UIC60.

18

The effect of carbon content on selected mechanical properties of model Mn-Cr-Mo alloy steels during tempering

Dziurka R., Pacyna J.

Inżynieria Materiałowa

|

2013

|

Vol. 34, nr 3

157--161

EN

The aim of this study is to explain inﬂuence of the kinetics of phase transformations during tempering on the fracture toughness of model steel with various carbon content. Optimum mechanical properties are achieved by proper design and careful implementation heat treatment technology. Above all it is necessary to avoid the temperature range 250÷400°C, in which the temper brittleness occurs. To determine the largest drop of impact strength related to the irreversible and reversible temper brittleness, the tempering was performed at temperature range of 100 to 600°C in steps of 50°C. For the WI steel the ﬁrst drop in toughness occurred after tempering at 300°C, which is associated with irreversible temper brittleness effect. Another drop in impact strength occurred for the tempering temperature of 500°C and is associated with the reversible temper brittleness effect. For the WII steel the ﬁrst drop in toughness occurred after tempering at 250°C, which is associated with irreversible temper brittleness effect. The effect of reversible brittleness is associated with a drop in toughness, which was marked during tempering at 550°C. For the WIII, the ﬁrst slight drop in impact strength was observed at 250°C while the minimum occurred after tempering at 300°C. This drop in impact strength is most likely associated with the irreversible temper brittleness. The second minimum in impact strength associated with reversible brittleness was similar as in the case of the WI steel at 500°C.

PL

Celem badań było określenie skłonności trzech nowych modelowych stali stopowych do wystąpienia efektu kruchości odpuszczania I rodzaju. Badania wykonano na trzech stalach modelowych chromowo-manganowo-molibdenowych o zróżnicowanej zawartości węgla. Ponadto w pracy zbadano wpływ przemian fazowych przy odpuszczaniu na własności mechaniczne tych stopów. Uzyskanie optymalnych właściwości mechanicznych stali jest możliwe dzięki prawidłowemu zaprojektowaniu technologii i starannemu wykonaniu ich obróbki cieplnej. Przede wszystkim należy unikać zakresu temperatury, w którym może występować kruchość odpuszczania I rodzaju (250÷400°C). W celu określenia największego nasilenia kruchości odpuszczania I rodzaju wykonano odpuszczanie w temperaturze od 100 do 600°C co 50°C. Próbki odpuszczano przez 2 godziny. Pierwszy zmniejszenie udamości dla wytopu WI stwierdzono po odpuszczaniu w temperaturze 300°C, co należy wiązać z kruchością odpuszczania I rodzaju. W obrębie tej kruchości najmniejszą udamość stal ta miała po odpuszczaniu w 350°C. Kolejny spadek udarności zaznaczył się dopiero dla temperatury odpuszczania 500°C i jest związany z efektem kruchości odpuszczania II rodzaju. Zmniejszenie udarności jest mniejsze niż w przypadku wystąpienia efektu kruchości I rodzaju. Dla wytopu WII pierwsze duże zmniejszenie udarności zaobserwowano po odpuszczaniu w temperaturze 250°C, co należy wiązać z kruchością odpuszczania I rodzaju. Efekt kruchości II rodzaju wystąpił po odpuszczaniu w 550°C. Dla wytopu WIII pierwszy niewielki spadek udarności stwierdzono po odpuszczaniu w temperaturze 250°C, natomiast najmniejszą udarność zmierzono po odpuszczaniu w temperaturze 300°C, co jest związane z kruchością odpuszczania I rodzaju. Drugie minimum udarności związane z wystąpieniem kiuchości odpuszczania II rodzaju zaznaczyło się, podobnie jak w przypadku wytopu WI, po odpuszczaniu w 500°C.

19

Effect of heating rate on the phase transformations during tempering of low carbon Cr-Mn-Mo alloy steel

Dziurka R., Pacyna J., Tokarski T.

Archives of Materials Science and Engineering

|

2013

|

Vol. 63, nr 1

13--18

EN

Purpose: The effect of heating rate to the tempering temperature on the microstructure and properties of lath martensite tempered at a various temperatures was studied in literature from point of the cemntite precipitations view. It has been shown that cementite dispersion is finer and more uniform in the rapidly heated and tempered than in the slowly heated and tempered specimen. Aim of this work is to investigate the effect of heating rate on the phase transformations during tempering. Design/methodology/approach: The investigations of phase transformations during tempering of the low carbon steel were made on the grounds of dilatometric curves recorded during heating from as-quenched state. Heating to isothermal holding at 350°C was made with two different heating rates (100°C/s and 5°C/s) and was performed by use of the L78 R.I.T.A. dilatometer made by Linseis. The investigations of phase transformations during continuous heating from as-quenched state were performed by use of the DT 1000 dilatometer made by Adamel. Findings: It is possible to reduce probability of the occurrence of some phase transformations in favor of other. The difference in advancement of the various phase transformations can effects on various mechanical properties of the steels. Research limitations/implications: The effect of the heating rates (100°C/s and 5°C/s) during heating from as-quenched state on the phase transformations during isothermal holding at 350°C was submitted. It is expected to carry out further research on the effect of the heating rate on the phase transformations during isothermal holding at different temperatures and their effects on mechanical properties. Practical implications: The obtained information may be used to design new technologies of steels tempering. Originality/value: The new point of view on the tempering of the steels can be assumed.

20

Influence of the Carbon Content on the Kinetics of Phase Transformations During Continuous Heating from As-Quenched State in a Cr-Mn-Mo Model Alloys

Dziurka R., Pacyna J.

Archives of Metallurgy and Materials

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2012

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Vol. 57, iss. 4

943-950

EN

The presented work concerns the research on the kinetics of phase transformations during continuous heating from as-quenched state of three Cr-Mn-Mo model alloys with a different carbon content. The kinetics of phase transformations during continuous heating of investigated alloys was presented on the CHT (Continuous, Heating, Transformation) diagrams. The CHT diagrams were made on the grounds of dilatograms recorded for quenched samples, heated with various rates. Also the methodology of the dilatometric samples preparation and the method of the characteristic points determination was described. The investigated alloys are the model alloys. Taking into account their chemical compositions the possibility of improving their properties by means of the heat treatment can be expected. The investigations of the carbon influence on microstructures of model alloys with Cr-Mn-Mo were carried out. Broadening the knowledge on the carbon influence on the kinetics of phase transformations during continuous heating from as-quenched state, will help in designing new alloys with a better properties.

PL

Niniejsza praca zawiera badania kinetyki przemian fazowych przy nagrzewaniu ze stanu zahartowanego trzech modelowych stopów Cr-Mn-Mo o różnej zawartości węgla. Kinetyka przemian fazowych przy nagrzewaniu badanych stopów jest przedstawiona za pomocą wykresów CHT. Wykresy CHT zostały wykonane na podstawie dylatogramów nagrzewania z różnymi szybkościami uprzednio zahartowanych próbek. Ponadto w pracy zamieszczono metodologie przygotowania próbek do badań dylatometrycznych i przykłady wyznaczania punktów charakterystycznych. Badane stopy sa stopami modelowymi. Biorąc pod uwagę ich składy chemiczne istnieje możliwość poprawy ich właściwości za pomoca obróbki cieplnej. W pracy została podjęta próba zbadania wpływu węgla na mikrostrukture stopów Cr-Mn-Mo po odpuszczaniu. Niniejsze badania poszerza wiedzę na temat wpływu węgla na kinetykę przemian fazowych przy nagrzewaniu ze stanu zahartowanego, co pomoże w projektowaniu nowych stopów o lepszych własnościach.