Wyniki wyszukiwania - BazTech

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Low-carbon cast microalloyed steel intercritically heat-treated at different temperatures: microstructure and mechanical properties

Torkamani Hadi, Raygan Shahram, Mateo Carlos Garcia, Palizdar Yahya, Rassizadehghani Jafar, Vivas Javier, San-Martin David

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 2

492--507

EN

In this study, dual-phase (DP, ferrite + martensite) microstructures were obtained by performing intercritical heat treatments (IHT) at 750 and 800°C followed by quenching. Decreasing the IHT temperature from 800 to 750°C leads to: (i) a decrease in the volume fraction of austenite (martensite after quenching) from 0.68 to 0.36; (ii) ~ 100°C decrease in martensite start temperature (Ms), mainly due to the higher carbon content of austenite and its smaller grains at 750°C; (iii) a reduction in the block size of martensite from 1.9 to 1.2 μm as measured by EBSD. Having a higher carbon content and a finer block size, the localized microhardness of martensite islands increases from 380 HV (800°C) to 504 HV (750°C). Moreover, despite the different volume fractions of martensite obtained in DP microstructures, the hardness of the steels remained unchanged by changing the IHT temperature (~ 234 to 238 HV). Applying lower IHT temperature (lower fraction of martensite), the impact energy even decreased from 12 to 9 J due to the brittleness of the martensite phase. The results of the tensile tests indicate that by increasing the IHT temperature, the yield and ultimate tensile strengths of the DP steel increase from 493 to 770 MPa, and from 908 to 1080 MPa, respectively, while the total elongation decreases from 9.8 to 4.5%. In contrast to the normalized sample, formation of martensite in the DP steels could eliminate the yield point phenomenon in the tensile curves, as it generates free dislocations in adjacent ferrite.

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Wytop staliwa dwufazowego sposobem odzyskowym

Bartocha D.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 3 spec.

3--8

PL

W pracy przedstawiono wyniki próbnych wytopów staliwa GX2CrNiMoCuN25-6-3-3 przeprowadzonych w otwartym laboratoryjnym piecu indukcyjnym sposobem odzyskowym. Wytopy polegały na przetopieniu złomu staliwa duplex, a zabiegi ograniczono tylko do końcowego odtlenienia. W ramach każdego wytopu wykonane zostały odlewy próbne schodkowe. Przedstawiono wyniki badań składu chemicznego i określono jego zmiany w różnym stadium wytopu. Na podstawie badań mikrostruktury i symulacji krzepnięcia odlewów próbnych określono wpływ szybkości stygnięcia na strukturę badanego staliwa.

EN

In the article the results of trial melts of cast steel grade GX2CrNiMoCuN25-6-3-3 conducted in an open laboratory inductive furnace with regenerative method are presented. Melts consisted on remelting scrap of duplex cast steel, and metallurgical treatment is limited only to the final deoxidation. Within each melts step-test castings are made. The results of chemical composition analysis are presented and it changes in the various stages of melting have been determined. On the basis of microstructure analysis and simulation of casting solidification, the effect of cooling rate on the structure of the tested cast steel has been estimated.

3

Wideogrametryczna ocena struktur dwufazowych gaz - ciało stałe w przestrzeni międzyrurowej wymiennika ciepła

Anweiler S., Szmolke N.

Inżynieria i Aparatura Chemiczna

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2006

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Nr 6s

9-11

EN

The aim of the work was to determine two-phase flow structures formed inside the shell-and-tube heat exchanger by the examination of pbase concentration distribution unevenness. The optical method based on fast digital photography and dynamic analysis of image brightness level changes and stochastic analysis of character of these fluctuations were used for the visualization of two-phase flow structures.

4

Analiza strukturalna wyżarzanych blach ze stali 0H24N6Mo1,5 typu duplex

Ryś J., Ratuszek W., Witkowska M.

Hutnik, Wiadomości Hutnicze

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2004

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Vol. 71, nr 7-8

414-418

PL

Badania dotyczyły analizy struktury i tekstury po wyżarzaniu i rekrystalizacji blach ze stali nierdzewnej 0H24N6Mo1,5 typu duplex, walcowanych na zimno do 70% i 90% deformacji oraz wyżarzanych w zakresie temperatur 800 - 1000 st. C przez rózne okresy. W trakcie wyżarzania obserwowano istotne zmiany strukturalne wpływające na tworzenie się tekstur ferrytu i austenitu. Rozwój tekstur wyżarzania wynikał z procesów zdrowienia i rekrystalizacji w obu składowych fazach oraz procesów związanych z rozkładem ferrytu i wydzielaniem fazy sigma. Struktura i tekstura blach ze stali typu duplex po wyżarzaniu i rekrystalizacji wynika z różnego udziału tych procesów, które uzależnione są od składu chemicznego i fazowego badanej stali, końcowej tekstury walcowania obu faz oraz stabilności fazowej przy różnych temperaturach wyżarzania.

EN

The invastigations concerned structure and texture analysis after recrystallization and annealing of duplex type 0H24N6Mo1.5 stainless steel sheets, cold - rolled up to 70% and 90% of reduction and annealed over the temperature range 800 degree Celsius - 1000 degree Celsius for various time periods. Significant structural changes were observed in the course of annealing treatment affecting formation of the ferrite and austenite texture. Development of annealing textures resulted from recovery and recrystallization processes in both component phases and processes connected with ferrite decomposition and precipitation of sigma phase. Structure and texture of duplex type steel sheets after annealing and recrystallization result from different contribution of these processes, which depend on the chemical and phase composittion of examined steel, the rolling texture of both component phase stability at different annealing temperatures.