Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 11
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

The paper presents the results of investigation into the technological possibility of making light-section castings of GX2CrNiMoN25-6-3

cast steel. For making castings with a wall thickness in the thinnest place as small as below 1 mm, the centrifugal casting technology was

employed. The technology under consideration enables items with high surface quality to be obtained, while providing a reduced

consumption of the charge materials and, as a result, a reduction in the costs of unit casting production.

Go to article

Authors and Affiliations

G. Stradomski
M. Nadolski
Z. Stradomski
Download PDF Download RIS Download Bibtex

Abstract

The paper presents the results of research on the microstructure of GX2CrNiMoCuN25-6-3-3 and GX2CrNiMoCuN25-6-3 cast steels with

a varying carbon content. The cause for undertaking the research were technological problems with hot cracking in bulk castings of duplex

cast steel with a carbon content of approx. 0.06% and with 23% Cr, 8.5% Ni, 3% Mo and 2.4% Cu. The research has shown

a significant effect of increased carbon content on the ferrite and austenite microstructure morphology, while exceeding the carbon content

of 0.06% results in a change of the shape of primary grains from equiaxial to columnar.

Go to article

Authors and Affiliations

G. Stradomski
Download PDF Download RIS Download Bibtex

Abstract

This article discusses the influence of Tungsten Inert Gas (TIG) surfacing of duplex cast steel on its hardness and structure. The samples of 24Cr-5Ni-2.5Mo ferritic-austenitic cast steel were subjected to single-overlay processes with the use of solid wire having the chemical composition similar to that of the duplex cast steel. As a result of the surfacing, the welds were obtained that had no welding imperfections with a smooth transition to the base material. In the test without the heat treatment, directly below the fusion line, we observe a ferrite band with a width of approximately 200 m without visible austenite areas. Some of the samples were then solution treated (1060°C). Both variants, without and after solution heat treatment, were subjected to testing. Significant changes in the microstructure of the joint were observed after the heat treatment process (heat affected zone and weld microstructure changes). In both areas, an increase in the austenite volume fraction after solution heat treatment was observed. Changes in the microhardness of the ferrite in the HAZ area directly below the fusion line were also observed.
Go to article

Authors and Affiliations

B. Kalandyk
J. Kasińska
A. Skrzypczyk
Download PDF Download RIS Download Bibtex

Abstract

The paper is concerned with comparing the methods for determining the ferrite content in castings from duplex stainless steels. It uses Schaeffler diagram, empirical formula based calculation, image analysis of metallographic sample, X-ray diffraction and measurement with a feritscope. The influence of wall thickness of the casting on the ferrite content was tested too. The results of the experiments show that the casting thickness of 25 or 60 mm does not have a significant effect on the measured amount of ferrite. The image analysis of metallographic sample and the measurement with the feritscope appear to be the most suitable methods. On the contrary, predictive methods, such as Schaeffler diagram or empirical formula based calculation are only indicative and cannot replace the real measurements. X-ray diffraction seems to be the least suitable measuring method. Values of ferrite content measured in such a way often deviated from the values measured by image analysis and with feritscope.

Go to article

Authors and Affiliations

V. Kaňa
V. Pernica
A. Zadera
V. Krutiš
Download PDF Download RIS Download Bibtex

Abstract

In the high-alloy, ferritic - austenitic (duplex) stainless steels high tendency to cracking, mainly hot-is induced by micro segregation

processes and change of crystallization mechanism in its final stage. The article is a continuation of the problems presented in earlier

papers [1 - 4]. In the range of high temperature cracking appear one mechanism a decohesion - intergranular however, depending on the

chemical composition of the steel, various structural factors decide of the occurrence of hot cracking. The low-carbon and low-alloy cast

steel casting hot cracking cause are type II sulphide, in high carbon tool cast steel secondary cementite mesh and / or ledeburite segregated

at the grain solidified grains boundaries, in the case of Hadfield steel phosphorus - carbide eutectic, which carrier is iron-manganese and

low solubility of phosphorus in high manganese matrix. In duplex cast steel the additional factor increasing the risk of cracking it is very

"rich" chemical composition and related with it processes of precipitation of many secondary phases.

Go to article

Authors and Affiliations

G. Stradomski
Download PDF Download RIS Download Bibtex

Abstract

Duplex cast steel it is a material with great potential. The properties of this material have contributed to its wide application in many industrial sectors, for example: oil extraction, printing, petrochemical industry, energy - flue gas desulphurization systems, seawater desalination plants, shipbuilding industry. The article presents the results of tribological tests following the static pressure roller burnishing (SPRB) process of GX2CrNiMoN22-5-3 duplex cast steel. The tests provided a basis for assessing the effect of the burnishing parameters on tribological properties of that material. The issue is important because the authors focused their research on duplex cast steels grade that are not containing copper. The article presents part of the research concerning the influence of the burnishing process on the properties of the duplex steel surface layer. Copper in duplex steels affects many areas one of them is the plastic properties. Its absence also reduces castability. Because of that it is reasonable to determine to what extent the properties of the surface layer of copper-free duplex cast steel grades can be shaped in burnishing process.
Go to article

Authors and Affiliations

G.E. Stradomski
1
ORCID: ORCID
J. Fik
2
ORCID: ORCID
D. Rydz
1
ORCID: ORCID

  1. Czestochowa University of Technology, Faculty of Production Engineering and Materials Technology, Poland
  2. Department of Advanced Computational Methods, Jan Dlugosz University in Czestochowa
Download PDF Download RIS Download Bibtex

Abstract

The paper, which is a summary and supplement of previous works and research, presents the results of numerical and physical modeling of the GX2CrNiMoCuN25-6-3 duplex cast steel thin-walled castings production. To obtain thin-walled castings with wall in the thinnest place even below 1 mm was used the centrifugal casting technology and gravity casting. The analyzed technology (centrifugal casting) enables making elements with high surface quality with reduced consumption of batch materials and, as a result, reducing the costs of making a unitary casting. The idea behind the production of cast steel with the use of centrifugal technology was to find a remedy for the problems associated with unsatisfactory castability of the tested alloy.

The technological evaluation of the cast construction was carried out using the Nova Flow & Solid CV 4.3r8 software. Numerical simulations of crystallization and cooling were carried out for a casting without a gating system and sinkhead located in a mold in accordance with the pouring position. It was assumed that the analyzed cast will be made in the sand form with dimensions 250×250×120 mm.

Go to article

Authors and Affiliations

G. Stradomski
M. Nadolski
ORCID: ORCID
A. Zyska
B. Kania
D. Rydz
ORCID: ORCID
Download PDF Download RIS Download Bibtex

Abstract

The paper presents the research results concerning the chromium-nickel-molybdenum duplex cast steel GX2CrNiMoCuN 25-6-3-3 grade. The aim of studies was the description of the influence of hyperquenching temperature Tp i.e. 1100, 1125 and 1150℃ on microstructure and mainly mechanical properties i.e. tensile strength UTS, yield strength YS, hardness HB, elongation EL and impact energy KV of duplex cast steel GX2CrNiMoCuN 25-6-3-3 grade. The range of studies included ten melts which were conducted in foundry GZUT S.A. Based on the obtained results was confirmed that application of hyperquenching process guarantees the elimination of brittle s phase in the microstructure of studied duplex cast steel. Moreover on the basis of conducted statistical analysis of the researches results is concluded that with the decrease in hyperquenching temperature increases ductility and amount of austenite, while decreases strength and amount of ferrite in studied duplex cast steel GX2CrNiMoCuN 25-6-3-3 grade.

Go to article

Authors and Affiliations

P. Jurczyk
ORCID: ORCID
T. Wróbel
ORCID: ORCID
Cz. Baron
Download PDF Download RIS Download Bibtex

Abstract

The examined material comprised two grades of corrosion-resistant cast steel, namely GX2CrNiMoN25-6-3 and GX2CrNiMoCuN25-6-3-

3, used for example in elements of systems of wet flue gas desulphurisation in power industry. The operating conditions in media heated

up to 70°C and containing Cl- and SO4 ions and solid particles produce high erosive and corrosive wear.The work proposes an application

of the σ phase as a component of precipitation strengthening mechanism in order to increase the functional properties of the material.

The paper presents the results of examination of the kinetics of σ phase precipitation at a temperature of 800°C and at times ranging from

30 to 180 minutes. Changes in the morphology of precipitates of the σ phase were determined using the value of shape factor R.

Resistance to erosion-corrosion wear of duplex cast steel was correlated with the kinetics of sigma phase precipitating.

Go to article

Authors and Affiliations

A. Brodziak-Hyska
Z. Stradomski
C. Kolan
Download PDF Download RIS Download Bibtex

Abstract

High-alloy corrosion-resistant ferritic-austenitic steels and cast steels are a group of high potential construction materials. This is

evidenced by the development of new alloys both low alloys grades such as the ASTM 2101 series or high alloy like super or hyper duplex

series 2507 or 2707 [1-5]. The potential of these materials is also presented by the increasing frequency of sintered components made both

from duplex steel powders as well as mixtures of austenitic and ferritic steels [6, 7]. This article is a continuation of the problems presented

in earlier works [5, 8, 9] and its inspiration were technological observed problems related to the production of duplex cast steel.

The analyzed AISI A3 type cast steel is widely used in both wet exhaust gas desulphurisation systems in coal fired power plants as well as

in aggressive working environments. Technological problems such as hot cracking presented in works [5, 8], with are effects of the rich

chemical composition and phenomena occurring during crystallization, must be known to the technologists.

The presented in this work phenomena which occur during the crystallization and cooling of ferritic-austenitic cast steel were investigated

using numerical methods with use of the ThermoCalc and FactSage® software, as well with use of experimental thermal-derivative

analysis.

Go to article

Authors and Affiliations

G. Stradomski
Download PDF Download RIS Download Bibtex

Abstract

The paper presents the results of examination concerning optimization of the σ phase precipitates with respect to the functional properties of ferritic-austenitic cast steel. The examined material comprised two grades of corrosion-resistant cast steel, namely GX2CrNiMoN25-6-3 and GX2CrNiMoCuN25-6-3-3, used for example in elements of systems of wet flue gas desulphurisation in power industry. The operating conditions in media heated up to 70°C and containing Cl- and SO4 ions and solid particles produce high erosive and corrosive wear. The work proposes an application of the σ phase as a component of precipitation strengthening mechanism in order to increase the functional properties of the material. Morphology and quantities of σ phase precipitates were determined, as well as its influence on the erosion and corrosion wear resistance. It was shown that annealing at 800°C or 900°C significantly improves tribological properties as compared with the supersaturated state, and the best erosion and corrosion wear resistance achieved due to the ferrite decomposition δ → γ’ + σ was exhibited in the case of annealing at the temperature of 800°C for 3 hours.

Go to article

Authors and Affiliations

Z. Stradomski
A. Brodziak-Hyska
C. Kolan

This page uses 'cookies'. Learn more