Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 14
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

This research paper shows the influence of a repeated SPD (Severe Plastic Deformation) plastic forming with the DRECE technique (Dual Rolls Equal Channel Extrusion) on hardening of low carbon IF steel. The influence of number of passes through the device on change of mechanical properties, such as tensile strength TS and yield stress YS, of tested steel was tested. The developed method is based on equal channel extrusion with dual rolls and uses a repeated plastic forming to refinement of structure and improve mechanical properties of metal bands [1-2]. For the tested steel the increase of strength properties after the DRECE process was confirmed after the first pass in relation to the initial material. The biggest strain hardening is observed after the fourth pass.

Go to article

Authors and Affiliations

K. Kowalczyk
M. Jabłońska
S. Rusz
I. Bednarczyk
Download PDF Download RIS Download Bibtex

Abstract

This paper shows results of researches of a structure and mechanical properties of metal sheets of IF steels subjected torecrystallization

annealing. The annealing was held in the scope of the temperature of 600-900°C over 25 min time. The impact of heat treatment on changes of properties and structure of the researches steel has been analysed. During annealing typical processes of rebuilding of the structure deformed as a result of cold deformation in the form of forming new recrystallized grains and their growth were observed. As the temperature of annealing increases the hardness of the material gradually decreases.

Go to article

Authors and Affiliations

K. Kowalczyk
M. Jabłońska
S. Rusz
G. Junak
Download PDF Download RIS Download Bibtex

Abstract

The aim of the performed experiments was to determine the influence of a cooling rate on the evolution of microstructure and hardness of the steel 27MnCrB5. By using dilatometric tests performed on the plastometer Gleeble 3800 and by using mathematical modelling in the software QTSteel a continuous cooling transformation diagram for a heating temperature of 850°C was constructed. Conformity of diagrams constructed for both methods is relatively good, except for the position and shape of the ferrite nose. The values of hardness, temperatures of phase transformations and the volume fractions of structural phases upon cooling from the temperature of 850°C at the rate from 0.16°C · s–1 to 37.2°C · s–1 were determined. Mathematically predicted proportion of martensite with real data was of relatively solid conformity, but the hardness values evaluated by mathematical modelling was always higher.
Go to article

Authors and Affiliations

I. Schindler
P. Kawulok
J. Mizera
S. Rusz
R. Kawulok
P. Opěla
M. Olszar
K.M. Čmiel
Download PDF Download RIS Download Bibtex

Abstract

Nil strength temperature of 1062°C and nil ductility temperature of 1040°C were experimentally set for CuFe2 alloy. The highest formability at approx. 1020°C is unusable due to massive grain coarsening. The local minimum of ductility around the temperature 910°C is probably due to minor formation of γ-iron. In the forming temperatures interval 650-950°C and strain rate 0.1-10 s–1 the flow stress curves were obtained and after their analysis hot deformation activation energy of 380 kJ·mol–1 was achieved. Peak stress and corresponding peak strain values were mathematically described with good accuracy by equations depending on Zener-Hollomon parameter.

Go to article

Authors and Affiliations

I. Schindler
M. Sauer
P. Kawulok
K. Rodak
E. Hadasik
M.B. Jabłońska
S. Rusz
V. Ševčák
Download PDF Download RIS Download Bibtex

Abstract

The work deal with an assembling and comparing of transformation diagrams of two low-alloy steels, specifically 16MnCrS5 and 20MnCrS5. In this work, diagrams of the type of CCT and DCCT of both steels were assembled. Transformation diagrams were assembled on the basis of dilatometric tests realized on the plastometer Gleeble 3800, of metallographic analyses and of hardness measurements. In addition, for comparison, the transformation diagrams were assembled even with use of the QTSteel 3.2 software. Uniform austenitization temperature of 850°C was chosen in case of both steels and even both types of diagrams. In case of both steels, an influence of deformation led to expected acceleration of phase transformations controlled by diffusion and also of bainite transformation. In both cases, the kinetics of martensitic transformation was not significantly affected by deformation.

Go to article

Authors and Affiliations

R. Kawulok
P. Kawulok
I. Schindler
P. Opěla
S. Rusz
V. Ševčák
Z. Solowski
Download PDF Download RIS Download Bibtex

Abstract

Two MgLiAl alloys of composition 4.5% Li and 1.5% Al (in wt.%) composed of α phase and of 9% Li, 1.5% Al composed of α (hcp) + β (bcc) phases were subjected to twist channel angular pressing (TCAP) deformation. Such deformation of α + β alloys caused less effective grain refinement than that of single α phase alloy. However, with increasing number of passes, grain size of single α phase alloy increased and that of β phase in two phase α + β alloy also grew, which suggested the effect of dynamic recrystallization. TEM studies allowed identifying particles of Li2MgAl phase of size of few μm. {001}<100> texture was observed in extruded alloy. Texture studies of extruded and TCAPed single phase hcp alloy indicated texture with {101 – 0} plane perpendicular to the extrusion direction and {0002} plane parallel to the extrusion direction. Duplex α + β alloys showed poor texture development.

Go to article

Authors and Affiliations

J. Dutkiewicz
S. Rusz
D. Kuc
O. Hilser
P. Bobrowski
B. Kania
Download PDF Download RIS Download Bibtex

Abstract

Suitable and complete sets of stress-strain curves significantly affected by dynamic recrystallization were analyzed for 11 different iron, copper, magnesium, titanium or nickel based alloys. Using the same methodology, apparent hot deformation activation energy Qp and Qss values were calculated for each alloy based on peak stress and steady-state stress values. Linear dependence between quantities Qp and Qss was found, while Qp values are on average only about 6% higher. This should not be essential in predicting true stress of a specific material depending on the temperature-compensated strain rate and strain.

Go to article

Authors and Affiliations

I. Schindler
ORCID: ORCID
P. Opěla
ORCID: ORCID
P. Kawulok
ORCID: ORCID
M. Sauer
ORCID: ORCID
S. Rusz
ORCID: ORCID
D. Kuc
K. Rodak
Download PDF Download RIS Download Bibtex

Abstract

A simple methodology was used for calculating the equivalent strain values during forming the sample alternately in two mutually perpendicular directions. This method reflects an unexpected material flow out of the nominal deformation zone when forming on the MAXStrain II device. Thus it was possible to perform two temperature variants of the simulation of continuous rolling and cooling of a long product made of steel containing 0.17% C and 0.80% Mn. Increasing the finishing temperature from 900°C to 950°C and decreasing the cooling rate from 10°C/s to 5°C/s led to a decrease in the content of acicular ferrite and bainite and an increase in the mean grain size of proeutectoid ferrite from about 8 µm to 14 µm. The result was a change in the hardness of the material by 15%.
Go to article

Authors and Affiliations

I. Schindler
1
ORCID: ORCID
P. Kawulok
1
ORCID: ORCID
K. Konečná
1
ORCID: ORCID
M. Sauer
1
ORCID: ORCID
H. Navrátil
1
ORCID: ORCID
P. Opěla
1
ORCID: ORCID
R. Kawulok
1
ORCID: ORCID
S. Rusz
1
ORCID: ORCID

  1. VŠB – Technical University of Ostrava, Faculty of Materials Science and Technology, Ostrava, Czech Republic

This page uses 'cookies'. Learn more