Wyniki wyszukiwania - Biblioteka Nauki

1

Struktura i własności mechaniczne spiekanych stali manganowych obrobionych cieplnie

100%

Sułowski M.

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2006

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tom R. 51, nr 5

292-299

PL

Przedstawiono wyniki badań dotyczące wpływu dodatkowej obróbki cieplnej na strukturę i własności konstrukcyjnych spiekanych stali manganowych. Badania prowadzono na spiekanych stalach manganowych o zawartości 3 % mas. manganu, wytwarzanych na drodze jednokrotnego prasowania i spiekania, które następnie poddano zabiegowi odpuszczania w trzech temperaturach 200, 300 i 400°C w atmosferze wodoru; czas trwania procesu wynosił 60 minut. Zaprezentowane wyniki badań świadczą o znaczącym wpływie obróbki cieplnej na własności mechaniczne spiekanych stali manganowych.

EN

It this paper the effect of additional heat treatment operation on the structure and mechanical properties of PM manganese steels had been discussed. The experiments were carried out on sintered steels containing 3 wt.-% Mn, produced during single pressing and sintering cycle, which were subsequently 60 minutes tempered at 200, 300 and 400°C in hydrogen atmosphere. The results show the heat treatment operation has a significant effect on the mechanical properties of sintered structural manganese steels.

2

Modelling the hardenability and tempering of high strength steels

100%

Eliasson J. , Siwecki T. , Rodell B.

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2007

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tom Vol. 7, No. 1

54-60

EN

The aim of the present work is to develop the hardenability and tempering models for various quenching and tempering treatments of high strength/martensitic steels. The main aim for the steel industry is to reduce the number of tests (Jominy) that will be carried out during development of new hardened steel grades, thereby reducing costs in the development stage. Other important aims are tailoring of mechanical properties with respect to alloying of the steels and reduction of weight by usage of steels with higher strength. In many cases steels are over alloyed to ascertain full hardenability. This can however increase the cost of the steel with no beneficial gain in the mechanical properties. With the help of modelling hopefully over alloying can be avoided. So, the benefit with modelling is reduced costs for material development as well as production costs with improved properties of the final products. Basis for the hardenability model is divided in three sub-models: 1. Dissolution of particles during reheating. Alloying elements generally increase hardenability when in solution in the austenite. 2. Calculation of hardenability distance kinetically depending on the dissolution of particles. Equilibrium of elements in solution or in particles is determined with ThermoCalc with a database for HSLA steels. Multiplication factors for alloying elements based on Grossmans work are used for calculation of Ideal diameter for 50% martensite in the centre of a bar. For comparison with Jominy bars, the Ideal diameter is transformed to Jominy distance. Also boron is considered since many quenched steels contain this alloying element, having a large effect on hardenability. 3. Grain growth with consideration taken to particles and their dissolution. Larger grains increase hardenability. The hardenability model will be used specifically for steel containing less than 0.4% C. For low carbon steels modified relations should be used. Below 0.2% C alloying elements such as Cr and Mo contribute less to hardenability. Therefore other relations must be used to fully describe the influence of alloying elements on hardenability. Combination effects occur, not only due to presence of particles and their ability to dissolve during reheat. Also interaction effects such as those for Mo and Ni in low carbon steels. According to the literature a high Ni-content (>0.75 wt-%) increases the influence of Mo on hardenability. In general the influence of individual alloying elements are lower than for steels with higher C-contents. The tempering model is based on experimental information from the literature. In this sense it is empirical. By combining the data from hardenability calculations using the hardenability model room temperature hardness and ultimate tensile strength after tempering in the temperature range 20-700 °C are calculated. The final properties are dependent on dissolution of alloying elements already during reheat before quench. In this paper comparisons of different alloys are given for hardening and tempering. Examples of verifications to experimental data are given both for the hardenability model as well as the tempering model. The tempering model generally functions well in comparison with experimental data. The pre-history before quench is important and affects the level of hardness and strength. In current work we try to take this into consideration by first applying the hardenability model.

PL

Celem projektu jest opracowanie modeli hartowalności i odpuszczania dla różnych zabiegów obróbki cieplnej wysoko wytrzymałych stali martenzytycznych. Model hartowalności opracowany w KIMAB jest podzielony na trzy składowe: (i) Rozpuszczanie cząstek w czasie wygrzewania, (ii) Wyznaczenie obszarów zahartowanych w oparciu o kinetykę rozpuszczania cząstek i (iii) rozrost ziaren (uwzględniając wpływ rozmiaru i objętości cząstek na efekt piningu Zenera. Model hartowalności przewiduje Idealną Średnicę, odległość Jominy'ego dla 50% martenzytu oraz twardość powierzchni stali po hartowaniu. Przykłady obliczeń dla stali z SSAB Oxelósund są przedstawione w artykule i porównane z wynikami doświadczeń. W K1MAB opracowano również doświadczalny model odpuszczania, który opiera się na danych doświadczalnych zaczerpniętych z literatury. Obliczona została twardość i wytrzymałość na rozciąganie hartowanych stali, otrzymanych z Ovako Bar, po odpuszczeniu w temperaturach 150°-700°C, i wyniki porównano z pomiarami. Model odpuszczania funkcjonuje poprawnie i ogólit skano zgodność z danymi doświadczalnymi. Niemniej j historia zmian temperatury przed hartowaniem ma wpływ i powinna być uwzględniona, ponieważ rzutuje i twardość i wytrzymałość stali. Stosując razem modele hartowalności i odpuszczania można badać wpływ nierozpuszczonych cząstek na własności stali po obróbce cieplnej.

3

The kinetics of phase transformations during tempering of tool steels with different carbon content

100%

Bała P.

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2009

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tom Vol. 54, iss. 2

491-498

EN

The main purpose of this study was the description of phase transformation kinetics during continuous heating from the as-quenched state (tempering) of newly designed tool steels for mill rolls with different carbon content. Dilatometry was used to determine the characterictic temperatures of phase transformations occurring in the investigated steels during he4ating from the as-quenched condition. The paper contains interpretations of dilatometric curves and describes the influence of heating rate on the temperature range of occurrence of a particular transformationż The effect of carbon content on transformation strains was also studied.

PL

Celem niniejszej pracy był opis kinetyki przemian fazowych przy nagrzewaniu ciągłym ze stanu zahartowanego (odpuszczaniu) nowo zaprojektowanych stali narzędziowych na walce hutnicze o różnej zawartości węgla. Na podstawie badań dylatometrycznych wyznaczono zakresy występowania poszczególnych przemian fazowych podczas nagrzewania ze stanu zahartowanego. Zamieszczono interpretacje dylatogramów oraz opisano wpływ szybkości nagrzewania do odpuszczania na temperaturowe zakresy wystepowania poszczególnych przemian. Ponadto opisano wpływ zawartości węgla na efekty dylatacyjne towarzyszące poszczególnym przemianom.

4

The kinetics of phase transformations during continuous heating from as-quenched state in high-speed steels

84%

Bała P. , Pacyna J.

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2009

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tom Vol. 37, nr 1

5-12

EN

Purpose: The reason for writing this paper was to describe the kinetics of phase transformations during continuous heating from quenched state. In this investigation two high-speed steels of the variable concentration of W and Mo were used. Moreover, the differences in hardness of samples of the investigated steels in relationship to the heating rate were evaluated. Design/methodology/approach : The kinetics of phase transformations during continuous heating (tempering) from as-quenched state of investigated steels, was elaborated using a DT 1000 dilatometer of a French company Adamel. The microstructure of investigations steels in as-quenched state were examined by a light microscope Axiovert 200 MAT, scanning electron microscope Hitachi 3500N and transmission JEM200CX microscope. The measurements of hardness were performed with the Vickers HPO250 apparatus. Findings: Change of heating rate during tempering has strong influence on the temperatures of beginnings and the ends of individual transitions as well as on the accompanying dilatation effects. It was shown that in quenched high-speed steels a part of retained austenite was already transforming during heating for tempering, but its significant part transformed only during cooling process after tempering. Research limitations/implications: It has been found that the substitution of tungsten with molybdenum in HS6-5-2 steel has influenced mainly the stability of retained austenite and the temperature of precipitation beginning of MC (MCs) type carbides. Whereas the precipitation ranges of ε carbide and cementite in both steels are close. Practical implications: Description of phase transformations kinetics during continuous heating from as-quenched state in high-speed steels. Originality/value: This results should be of interest to engineers concerned with design new technologies of steel tempering.

5

The kinetics of phase transformations during the tempering of HS6-5-2 steel

84%

Bała P. , Pacyna J. , Krawczyk J.

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2009

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tom Vol. 35, nr 2

69-76

EN

Purpose: This work contains a detailed description of the kinetics of phase transformations during tempering of hardened HS6-5-2 high-speed steel. Moreover, the microstructure development in tested samples, reflecting the extend of the phase transformations during tempering, was discussed too. Design/methodology/approach: CHT diagram, illustrating the kinetics of phase transformations during continuous heating (tempering) from as-quenched state of investigated steel, was elaborated using a DT 1000 dilatometer of a French company Adamel. The influence of the heating rate on the retained austenite transformation as well as the results of threefold tempering at 560 °C were also determined. Findings: Heating of the investigated steel from the as-quenched state resulted in the occurrence of 4 primary transformations: precipitation of ε carbide, M₃C precipitation, transformation of retained austenite and precipitation of alloy carbides of MC and M₂C type. It was shown that in the quenched high-speed steels a part of retained austenite is already transformed during heating for tempering, but its significant part is transformed only during cooling after tempering as well as during consecutive heatings for temperings. Examination of the microstructure of investigated steel, mainly focused on microstructural development relating to the advancement of transformations during continuous tempering, showed an adequacy of the microstructural changes to CHT diagrams. Research limitations/implications: The new CHT diagram of investigated steel was determined. Practical implications: The obtained CHT diagram may be used to design new technologies of tempering of this steel. Originality/value: The new CHT diagram. Keywords: Tool materials; Tempering; CHT - diagram; Retained austenite

6

The Mössbauer spectroscopy studies of ε to cementite carbides transformation during tempering of high carbon tool steel

84%

Bała P. , Krawczyk J. , Hanc A.

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2008

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tom Vol. 32, nr 2

95-98

EN

Purpose: This work presents results of investigations using Mössbauer spectroscopy technique and their interpretation concerning transformation of ε to cementite carbides during tempering in relation to previously conducted dilatometric, microscopic and mechanical investigations. Investigations were performed on 120MnCrMoV8-6-4-2 steel. Design/methodology/approach: Samples taken from investigated steel were austenitized at the temperature of 900°C and hardened in oil. Austenitizing time was 20 minutes. After that, seven of eight samples were tempered. Tempering consisted of holding the samples at 200°C for defined periods. All the times mentioned above were selected basing on IHT (Isothermal Heating Transformations) diagram. Findings: The influence of the tempering time on nucleation and solubility of ε carbides, and on cementite nucleation and growth, was determined. Research limitations/implications: The analysis of phase transformations during various periods of tempering using Mössbauer spectroscopy technique made possible to reveal fine details connected with the processes. Practical implications: Optimum tempering time of tools made from the investigated steel should be in the range of 1.5-2h. Originality/value: Details descriptions of ε to cementite carbides transformation during isothermal heating from as-quenched state.

7

The kinetics of phase transformations during tempering in high-speed steels

84%

Bała P. , Pacyna J.

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2007

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tom Vol. 23, nr 2

15-18

EN

Purpose: This work contains a detailed description of the kinetics of phase transformations during continuous heating from quenched state of HS18-0-1 and HS6-5-2 high-speed steels. Design/methodology/approach: The kinetics of phase transformations during continuous heating (tempering) from as-quenched state of investigated steel, was elaborated using a DT 1000 dilatometer of a French company Adamel. Findings: During heating of previously quenched HS18-0-1 and HS6-5-2 steel samples, the presence of four basic transformations was found, i.e. precipitation of epsilon carbide, precipitation of M3C, transformation of retained austenite and precipitation of alloy carbides of MC and M2C type. It was shown that in quenched high-speed steels a part of retained austenite transforms already during heating for tempering, but its significant part transforms only during cooling process after tempering. Research limitations/implications: The substitution of tungsten with molybdenum in HS6-5-2 steel has influenced mainly the stability of retained austenite and the temperature of precipitation beginning of MC (MCS) type carbides. Practical implications: This results will be used to design new technologies of tempering of these steels. Originality/value: Characterization of kinetics phase transformations during continuous heating from quenched state in high-speed steels.

8

Kinetics of phase transformations during tempering of tool steels of a different chromium content

84%

Pacyna J. , Bała P. , Krawczyk J.

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tom Vol. 31, nr 3

243-246

EN

The kinetics of phase transformations during tempering (continuous heating from as-quenched state), in the form of the CHT diagrams (Continuous Heating Transformation) of two tool steels of a different chromium content (2.06 and 2.98%) and a similar carbon (app. 0.8%) and remaining alloying elements content, are presented in the paper. Investigations were performed by means of the DT1000 dilatometer. Transformations in samples during a continuous heating from as-quenched state with heating rates: 0.05÷35°C/s were recorded. The temperature ranges of carbide precipitations as well as transformations of the retained austenite were determined. The influence of a heating rate and an increase of the chromium content on the kinetics of phase transformation during tempering was shown.

PL

W pracy określono kinetykę przemian fazowych przy odpuszczaniu (nagrzewaniu ciągłym ze stanu zahartowanego) w formie wykresów CTPC (Czas-Temperatura-Przemiana) dwóch stali narzędziowych o różnej zawartości chromu 2,06% i 2,98% oraz zbliżonej zawartości węgla (ok. 0.8%) i pozostałych pierwiastków stopowych. Badania wykonano za pomocą dylatometru DT1000. Rejestrowano w próbkach przemiany podczas nagrzewania ciągłego ze stanu zahartowanego z szybkościami 0,05÷35°C/s. Określono zakresy temperatury wydzielania węglików oraz przemiany austenitu szczątkowego. Pokazano wpływ szybkości nagrzewania oraz zwiększenia zawartości chromu na kinetykę przemian fazowych przy odpuszczaniu.

9

Hartowanie i odpuszczanie walcowanego na gorąco żeliwa sferoidalnego

84%

Szykowny T. , Giętka T.

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2006

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tom R. 6, nr 19

349-354

PL

Próbki niskomiedziowego żeliwa sferoidalnego o początkowej grubości 3mm austenityzowano w temperaturze 920 C, walcowano ze zgniotem 33% i oziębiano w wodzie. Następnie przeprowadzono odpuszczanie w temperaturze 250 - 650 C. Dla celów porównawczych przeprowadzono taką samą obróbkę cieplną żeliwa nieodkształcanego. Wykonano badania metalograficzne, mikrofraktograficzne, dyfrakcyjne rentgenowskie oraz pomiary twardości.

EN

The samples of low-copper, ductile cast iron withe the initial thickness 3 mm were austenitized in temperature 920 C, they were strain rolled 33% and they were cooled down in the water. Next ductile cast iron was tempered in temperature 250 - 600 C. In comparison aims it was made the same heat treating of unstrained ductile cast iron an. The researches were performed using the following methods: metallography, fractography, X-ray diffraction and take measurements and hardnesses

10

Kinetyka przemian fazowych przy nagrzewaniu ze stanu zahartowanego nowej stali stopowej o dużej zawartości węgla

84%

Pacyna J. , Bała P. , Skrzypek T.

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2006

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tom Vol. 73, nr 2

46-49

PL

W pracy określono kinetykę przemian fazowych przy nagrzewaniu ciągłym (odpuszczaniu) ze stanu zahartowanego w postaci wykresu CTPc stopni (Czas - Temperatura - Przemiana) nowej stali stopowej zawierającej 1,22 %C. Na dylatogramach nagrzewania ze stanu zahartowanego wskazano temperatury charakterystyczne, użyte do wykonania CTPc tej stali. Ponadto, pokazano różnice w twardościach próbek badanej stali w zależności od stopnia zaawansowania przemian przy odpuszczaniu, jak również zamieszczono dokumentację metalograficzną.

EN

In the paper kinetics of phase transformations during continuous heating (tempering) from the hardened condition has been specified in from of a CHT diagram (Continuous Heating Transformations) of a new alloy steel containing 1,22 %C. In the dilatograms of heating from hardened condition characteristic temperatures used for the CHT diagram have been indicated. Moreover some differences in the hardness of the investigated steel samples depending on the level of advancement of changes at tempering have been shown, as well as metallographic documentation has been included.

11

The influence of kinetics phase transformation during tempering on the mechanical properties of HS6-5-2 steel

84%

Bała P. , Pacyna J.

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2008

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tom Vol. 28, nr 2

123-130

EN

Purpose: The reason for writing this paper was to describe the kinetics of phase transformations during tempering and the evaluation of the influence of pre-tempering on the properties of HS6-5-2 steel after principal tempering. Moreover, the differences in hardness of samples of the investigated steel in relationship to the heating rate were evaluated. The microstructure development in tested samples, reflecting the extend of the phase transformations during tempering, was discussed too. Design/methodology/approach: Dilatometric investigations were performed using a DT 1000 dilatometer of a French company Adamel. The microstructure of investigations steels were examined by transmission JEM200CX microscope. Due to high brittleness of test steel it was decided to test their strength with static bend test. The tests have been carried out on ø 5 samples using INSTRON testing machine. Evaluation of crack resistance of test steels has been made by means of linear elastic fracture mechanics method on the basis of the measurement of stress intensity factor KIc, in static bend test. Findings: Change of heating rate during tempering has strong influence on the temperatures of beginnings and the ends of individual transitions as well as on the accompanying dilatation effects. It has been stated that, in test steel in which remains a lot of retained austenite after hardening, the pre-tempering within the range of cementite precipitation and transformation of retained austenite, adversely affects the properties after principal tempering. Research limitations/implications: Description of the influence of phase transformation on the mechanical properties of HS6-5-2 high speed steel. Practical implications: It was shown, that advance (by pre-tempering) of selected phase transformations during tempering may affect steel properties after principal tempering. Originality/value: This results should be of interest to engineers concerned with design new technologies of steel tempering.

12

The influence of deep cryogenic treatment on transformations during tempering of quenched D2 steel studies of XRD, structures, DSC, dilatometry, hardness and impact energy

84%

Wierszyłłowski I. , Samolczyk J. , Wieczorek S. , Andrzejewska E. , Niemczyk W.

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2008

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tom T. 19, nr 2

53-59

EN

The study analyses the influence of cryogenic treatment on the resultant structures, the development of changes during tempering and the properties obtained. It was observed that cryo treatment affects the properties through: a significant reduction in retained austenite content, gradual reduction in value of martensite tetragonality and an increase in the number of carbon atoms participating in transformations during tempering. The consequence of the transformations taking place during cryogenic treatment is precipitation of ?-carbide instead of ?-carbide during low tempering. The number of ?-carbides precipitated is higher than that of ?-carbide. This affects the functional characteristics of steel.

PL

Podczas badań analizowano wpływ obróbki kriogenicznej na uzyskane struktury, przemiany podczas odpuszczania i uzyskiwane właściwości. Stwierdzono, że obróbka kriogeniczna wpływa na właściwości wskutek znacznego zmniejszenia zawartości austenitu szczątkowego, stopniowego obniżenia tetragonalności martenzytu i zwiększenia liczby atomów węgla biorących udział w przemianach podczas odpuszczania. W wyniku przemian zachodzących podczas obróbki kriogenicznej podczas odpuszczania wydziela się węglik ? zamiast węglika ?. Liczba węglików ? wydzielających się podczas odpuszczania jest większa niż liczba wydzielających się podczas obróbki konwencjonalnej węglików ? . Zmiany te mają wpływ na właściwości użytkowe stali.

13

Computer simulation of mechanical properties of quenched and tempered steel specimen

67%

Smoljan B. , Iljkić D. , Tomašić N.

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2010

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tom Vol. 40, nr 2

155-159

EN

Purpose: The computer simulation of mechanical properties of quenched and tempered steel was investigated. The established method of computer simulation was applied in prediction of mechanical properties of workpiece with complex form. Design/methodology/approach: The method of computer simulation of mechanical properties of quenched and tempered steel was established by theoretical analysis of relevant properties which have influence on hardness of quenched and tempered steel, and by regression analysis based on experimental results. Findings: The new method of prediction of mechanical properties of quenched and tempered steel was established. Proposed method of computer simulation of mechanical properties of quenched and tempered steel is based on predicted steel hardness. Hardness distribution of quenched and tempered workpiece of complex form was predicted by computer simulation of steel quenching using a finite volume method. It was found out that mechanical properties of quenched and tempered steel can be successfully predicted by proposed method. Research limitations/implications: The investigation was done on carbon and low alloyed steel. The further experimental investigations are needed for final verification of established model. Practical implications: The established method could be applied in industrial practice. Originality/value: As-quenched hardness distribution is predicted by involving the results of simple Jominy-test in numerical modelling of steel quenching. Estimation of hardness distribution is based on time, relevant for structure transforma- tion, i.e., time of cooling from 800 to 500°C (t8/5). The distribution of mechanical properties in quenched and tempered steel workpiece is estimated based on as-quenched steel hardness, tempering temperature and Jominy-test results.

14

Przeciwścierne warstwy kompozytowe na stalach narzędziowych.

67%

Rutkowska A. , Dąbrowski M. , Kosoń A. , Mąkol A.

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2002

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tom R. XXIII, nr 5

597-599

PL

W pracy podjęto prototypową próbę wytwarzania powłoki azotku tytanu (TiN) na uprzednio obrobionej cieplnie i naazotowanej stali narzędziowej do pracy na zimno gat. 165H12 (NC10). Obróbkę cieplną wykonano, stosując zróżnicowane temperatury odpuszczania. Stwierdzono, że zastosowanie obróbki powierzchniowej (N+TiN) dla wyżej wymienionej stali wydaje się celowe. Badania odporności na zużycie ścierne wykazały, że największą odporność uzyskały próbki odpuszczone przy temperaturze 450 stopni Celsjusza.

EN

A new prototype method of manufacturing TiN layer on heat-treated and nitrided hardened 165h12 (NC 10) for cold-work tool steel was undertaken in this study. The heat treatment using different tempering temperatures was carried out. It was found that applying surface treatment (N+TiN) to the mentioned above steel seems to be justified. The abrasion resistance research showed that specimen tempered at 450 degrees centigrade had the highest wearing quality.

15

An analysing of heat treatment process planning

67%

Smoljan B.

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2007

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tom Vol. 20, nr 1-2

563-566

EN

Purpose: Process planning of heat treatment has been investigated. The established approach of heat treating process planning is suitable for effective integration of heat treatment in computer added manufacturing. Design/methodology/approach: Process plan of heat treating process has been established based on fundamental process planning principals. The heat treatment was treated in the same as other manufacture processes. Findings: The general approach for process planning of heat treatment processes has been established. Heat treatment processes have to be designed into operations and sub-operations with the same principles that are also valid for other manufacturing processes. Research limitations/implications: The further research should be focused on development of methods for the better application of achieved results. Practical implications: This way of heat treatment process planning is more appropriate for integral trends of manufacturing, i.e., with the trend of introducing the modern systems in all parts of industrial manufacturing. Originality/value: The global approach of process planning of heat treatment processes was established and better unification with other manufacturing processes was achieved.

16

Effect of heat treatment on mechanical properties of H11 tool steel

67%

Qamar S. Z.

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2009

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tom Vol. 35, nr 2

115-120

EN

Purpose: AISI H11 is a special alloy steel, categorized as chromium tool steel. Because of its high toughness and hardness, it is well suited for hot work applications involving very high loads. Typical applications are hot-work forging and extrusion dies, helicopter rotor blades, etc. For longer life and higher design accuracy, properties of this type of tool steel can be improved by various types of heat treatment. Current work reports and analyzes results of mechanical testing performed on variously heat treated H11 steel samples, to arrive at an optimum heat treatment strategy for hot work applications. Design/methodology/approach: Tensile and impact test specimens were fabricated using precision milling and EDM. These samples were subjected to various heat treatment sequences, consisting of annealing, hardening, air and oil quenching, and tempering at different temperatures. Heat treated samples were then mechanically tested for hardness (Rockwell), impact toughness (Charpy), and tensile properties (yield strength, ultimate strength, ductility). Findings: Mechanical testing of H11 samples revealed that with increasing temper temperatures: (a) hardness first increases to a maximum and then gradually decreases; (b) impact toughness first decreases to a minimum and then increases; (c) yield strength first decreases, then increases, and then increases again; (d) ultimate strength first increases to a maximum and then steadily decreases; and (e) ductility (% elongation) gradually decreases till 600şC, and then increases rather sharply. Practical implications: Though a very promising candidate for hot-work applications, H11 steel is not commonly used for die and tool making. Results of this study can provide die designers and users in the metalworking industry with good guidelines to select proper heat treatment strategies to use H11 steel for various applications. Originality/value: Very little information is available in published literature about mechanical properties of H11 steel, especially after different types of heat treatment. Results from this study can fill some of this gap.

17

Submerged arc overlaygin welding of structural steel by WC-Co powder

67%

Ambroza P. , Bockus S. , Kavaliauskiene L.

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2006

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tom Vol. 51, iss. 3

489-494

EN

Arc welding under a flux, using various materials, technologies and regimes, enables to obtain thick, wear resistant coatings. Simple, easily realized is arc welding of spread over powder layer. In this research WC-8%Co powder was spread on low carbon structural steel surface and melted by arc under the flux, containing graphite powder. The test performed show that using for overlaying welding under flux WC-8%Co powder, it is possible to obtain layers with large amount of carbides phase (about 90%); formation of carbides was influenced by both amount of WC-8%Co powder spread over the structural steel surface, and amount of graphite powder, mixed with flux. Electric arc between welding wire and base metal resulted, due to high temperature, melting of WC carbide in powder and formation of Fe3W3C carbide during cooling, because the iron into welding bath came from both melted welding wire and structural steel surface. The microstructure was obtained in which carbides are bonded by the matrix, having alloyed steel composition. The matrix is composed of martensite, troostite and retained austenite. Amount of those phases depends on the amount of alloying elements (W, Co, Mn and Si), and amount of carbon, as well as heat treatment. The overlaying welded layers obtained had been more wear resistant than standard tool steel X12M (Russian Standard GOST 5950-73) of similar hardness.

PL

Spawanie łukowe pod topnikiem różnych materiałów na skale przemysłową pozwala otrzymać grube, odporne na ścieranie powłoki. Stosunkowo łatwo zrealizować jest spawanie łukowe nakładane pod warstwą proszku. W tej pracy, proszek WC-8%Co był nakładany na powierzchnię nisko węglowej stali konstrukcyjnej i topiony łukowo pod topnikiem, zawierającym sproszkowany grafit. Przeprowadzone próby wykazały, że używając napawania pod topnikiem proszkiem WC-8%Co, można otrzymać powłoki z dużą zawartością fazy węglików (około 90%); na tworzenie węglików wpływa zarówno ilość WC-8%Co nakładanego na powierzchnie stali konstrukcyjnej jak i na ilość proszku grafitowego zmieszanego z topikiem. Łuk elektryczny jaki powstaje pomiędzy drutem spawalniczym i metalem podłoża dzięki wysokiej temperaturze topi węglik WC w proszku i tworzy się podczas chłodzenia węglik Fe3W3C, ponieważ żelazo w kąpieli spawalniczej pochodzi zarówno z topionego drutu spawalniczego jak i powierzchni stali konstrukcyjnej. Otrzymano mikrostrukture w której wegliki sa zwiazane przez osnowe, posiadajaca skład stali stopowej. Osnowa jest złozona z martenzytu, trustytu i szczatkowego austenitu. Ilosc tych faz zalezy równiez od obróbki cieplnej. Otrzymane napawane powłoki są bardziej wytrzymałe na ścieranie niż stal narzędziowa X12M (rosyjski standard GOST 5950-73) o podobnej twardości.

18

Effect of chromium on the early stage of tempering of hypereutectoid steels

67%

Dąbrowski R. , Pacyna J.

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2008

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tom Vol. 53, iss. 4

1017-1023

EN

The article presents a quantitative evaluation of chromium influence on transformations during early stage of tempering of hypereutectoid steels. The tests have been conducted on a C110 carbon steel and a 115Cr5 steel containing 1.15% C and 1.23% Cr. The characteristic temperatures of early stages of tempering have been determined using dilatometric method on the basis of digitally recorded dilatograms of heating from ąuenched state at various rates, which have been subsequently differentiated. It has been pointed out that dissolution of 1.23% chromium in austenite has practically no influence on the temperaturę of contraction εs (most probably connected with precipitation of ε carbide) taking place during early stage of tempering, while it increases both the temperaturę of contraction εf and the maximum of its intensity εmax as well. Furthermore, it has been revealed that fracture toughness (Kic) for the low-tempered (200°C) C110 steel, after previous quenching from homogeneous austenite range, is higher than that for the 115Cr5 alloy steel.

PL

W artykule dokonano ilościowej oceny wpływu chromu na przemiany zachodzące we wczesnym stadium odpuszczania stali nadeutektoidalnych. Badania wykonano na stali niestopowej C110 oraz stali 115Cr5 zawierającej 1,15% C i 1,23% Cr. Temperatury charakterystyczne wczesnego stadium odpuszczania określono metodą dylatometryczną na podstawie zarejestrowanych cyfrowo dylatogramów nagrzewania z różnymi szybkościami ze stanu zahartowanego, które poddano różniczkowaniu. Wykazano, że rozpuszczenie 1,23% chromu w austenicie praktycznie nie wpływa na temperaturę początku skurczu εs (najprawdopodobniej związanego z wydzielaniem węglika ε) zachodzącego we wczesnym stadium odpuszczania, natomiast podnosi zarówno temperaturę końca skurczu εf, jak również maksimum jego intensywności εmax. Ponadto wykazano, że odporność na pękanie (KIc) niskoodpuszczonej (200°C) stali C110, po uprzednim zahartowaniu z zakresu jednorodnego austenitu, jest większa niż stali stopowej 115Cr5.

19

Influence of the boride coatings on wearability of the yarn guide.

67%

Płonka S. , Suliga I. , Trybalska B. , Kusiński J.

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1998

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tom R. XIX, nr 4

1108-1111

EN

The effectiveness of bath boronizing, hardening and tempering on the lifetime of the yarn guides has been studied. Examinations showed significant improvement of yarn guide lifetime after boronizing. Even that the boronized yarn guides were tested during almost 3 times longer time (20800 hrs) their mean degree was more than 13 times lower than that of conventionally treated ones whose were tested during the time of 7700 hrs.

20

Badania strukturalne mechanizmu odkształcenia na zimno stali przez zgniatanie obrotowe

67%

Stępień J.

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2007

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tom Vol. 27, nr 1

169-177

PL

Zgniatanie obrotowe na zimno stali niskowęglowej Cr-Mn-Mo-V stosuje się w celu uzyskania w wyrobie gotowym bardzo drobnej struktury. Uzyskanie bardzo drobnej struktury pozwala na podwyższenie właściwości wytrzymałościowych wyrobu gotowego przy bezpiecznym poziomic wydłużenia A5 powyżej 10%. Zgniatanie obrotowe wykonano na dwóch stanowiskach: na stanowisku doświadczalnym FPS Bolechowo, stosując stal wytapianą z zastosowaniem pozapiecowej obróbki próżniowej VAD, i na stanowisku produkcyjnym niemieckiej firmy MSR, stosując stal przetapianą elektrożużlowo EŻP. Stwierdzono, że mikrostruktura stali EŻP jest bardziej jednorodna i bardziej drobnoziarnista niż stali VAD, zarówno po ulepszaniu cieplnym jak i po zgniataniu obrotowym na zimno. Niskowęglowa stal Cr-Mn-Mo-V po hartowaniu z temperatury 970°C i odpuszczaniu w temperaturze ok. 660°C ma wydłużenie A5 od 12,0 do 12,9% przy Rm od 1114 do 1154 MPa i spełnia założone kryteria: przy Rm = 1080 + 1280 MPa A5≥ > 10. Po odkształceniu na zimno wytrzymałość tej stali wzrasta do ok. 1500 MPa.

EN

Microstructure low-carbon Cr-Mn-Mo-V electro-slag remelted (ESR) steel was more homogenous and more fine-grained than vacuum argon decarburization (VAD) steel. The same was found after quenching and tempering and after cold rotary extrusion. Also, ESR steel has more lower banding structure introduced by segregation of chemical composition (major C and Mn). After cold rotary extrusion on the experimental stand of FPS and industry stand of MSR, both VAD and ESR steels had a fine-structure, witch was composed of thin lath tempered martensite. In the structure deformation bands appeared arranged in space in different directions and carbides of chromium and molybdenum type M6C (this carbides often were found in the VAD steel) and carbides vanadium type MC. The fine laths of martensite received in the ESR steel were deformed on the industry stand MSR. The low-carbon Cr-Mn-Mo-V steel after quenching from 970°C and tempering at about 660°C has elongation A5 = from 12.6 to 12.9% and strength Rm = from 1114 to 1154 MPa and fulfils criteria of standards: Rm - from 1080 to 1280 MPa, A5 ≥ 10. After cold rotary extrusion strength incrased to about 1500 MPa.