Effects of hot forging on the structural condition in HS 6-5-2 high-speed steel

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F49777513%3A23210%2F19%3A43958050" target="_blank" >RIV/49777513:23210/19:43958050 - isvavai.cz</a>

Výsledek na webu

<a href="https://iopscience.iop.org/article/10.1088/1757-899X/723/1/012002/pdf" target="_blank" >https://iopscience.iop.org/article/10.1088/1757-899X/723/1/012002/pdf</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/1757-899X/723/1/012002" target="_blank" >10.1088/1757-899X/723/1/012002</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Effects of hot forging on the structural condition in HS 6-5-2 high-speed steel

Popis výsledku v původním jazyce

Microstructure analysis was performed on rolled bars of high-speed steel after two and three forging cycles, each cycle comprising one upsetting and one drawing out operation. High-speed steels belong to difficult-to-form materials with a narrow forging temperature interval. Forging above the maximum forging temperature may lead to grain coarsening. Below the minimum forging temperature, deformation resistance of the material increases, and the workpiece may fail. Using numerical modelling, special forging dies were designed and effective strain distribution was calculated for an axial cross-section plane in specimens after two and three forging cycles. The purpose of the analysis was to identify the relationship between the amount of effective strain and the shape and size of austenite grain and the volume fraction and density of carbidesafter forging. The size of prior austenite grains was measured using the linear intercept method which is based on the Snyder-Graff method. Grain shapes were characterized in terms of circularity, which is the difference between the shape in question and a circle. With increasing amount of strain, the grains in the materialbecame finer, as undissolved carbides impeded grain growth. In as-received rolled condition, the austenite grain size was G9. After three forging cycles, it was smaller, G11 (the higher the number, the smaller the grains). Circularity characterizes the complexity of a grain shape.Micrographs of carbide particles were taken using a scanning electron microscope and examined with NISElements image analysis software. The majority of carbides were sized between 0.2 and 2μm.The carbides which are less than 1μm in size do not shrink in response to increasing strain and their quantity does not change appreciably. Carbides with a size of 1-2μm show a different behaviour. In the central region of specimens, where strain is the largest, their amounts are much larger than in less-worked regions.

Název v anglickém jazyce

Effects of hot forging on the structural condition in HS 6-5-2 high-speed steel

Popis výsledku anglicky

Microstructure analysis was performed on rolled bars of high-speed steel after two and three forging cycles, each cycle comprising one upsetting and one drawing out operation. High-speed steels belong to difficult-to-form materials with a narrow forging temperature interval. Forging above the maximum forging temperature may lead to grain coarsening. Below the minimum forging temperature, deformation resistance of the material increases, and the workpiece may fail. Using numerical modelling, special forging dies were designed and effective strain distribution was calculated for an axial cross-section plane in specimens after two and three forging cycles. The purpose of the analysis was to identify the relationship between the amount of effective strain and the shape and size of austenite grain and the volume fraction and density of carbidesafter forging. The size of prior austenite grains was measured using the linear intercept method which is based on the Snyder-Graff method. Grain shapes were characterized in terms of circularity, which is the difference between the shape in question and a circle. With increasing amount of strain, the grains in the materialbecame finer, as undissolved carbides impeded grain growth. In as-received rolled condition, the austenite grain size was G9. After three forging cycles, it was smaller, G11 (the higher the number, the smaller the grains). Circularity characterizes the complexity of a grain shape.Micrographs of carbide particles were taken using a scanning electron microscope and examined with NISElements image analysis software. The majority of carbides were sized between 0.2 and 2μm.The carbides which are less than 1μm in size do not shrink in response to increasing strain and their quantity does not change appreciably. Carbides with a size of 1-2μm show a different behaviour. In the central region of specimens, where strain is the largest, their amounts are much larger than in less-worked regions.

Druh

D - Stať ve sborníku

CEP obor

—

OECD FORD obor

20501 - Materials engineering

Projekt

<a href="/cs/project/TH02020161" target="_blank" >TH02020161: Vývoj vysoce legované oceli s vysokou metalurgickou čistotou, ultrajemnou strukturoua enormním stupněm protváření pro speciální aplikace</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

IOP Conference Series: Materials Science and Engineering

ISBN

—

ISSN

1757-8981

e-ISSN

1757-899X

Počet stran výsledku

9

Strana od-do

1-9

Název nakladatele

IOP Publishing Ltd

Místo vydání

Bristol

Místo konání akce

Plzeň

Datum konání akce

10. 9. 2019

Typ akce podle státní příslušnosti

EUR - Evropská akce

Kód UT WoS článku

—