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1
Content available remote Własności superwytrzymałej stali stopowej do ulepszania cieplnego o strukturze martenzytycznej i bainitycznej
Pawlak S. J.
Stal, Metale & Nowe Technologie
|
2018
|
nr 5-6
60--64
PL
W artykule przedstawiono rezultaty badań eksperymentalnych związanych z opracowywaniem superwytrzymałej stali przeznaczonej do zaawansowanych zastosowań konstrukcyjnych, m.in. w przemyśle lotniczym. W oparciu o badania mikrostruktury, własności mechanicznych i odporności na pękanie opracowano alternatywne sposoby obróbki cieplnej w stosunku do tradycyjnego hartowania z odpuszczaniem, takie jak wysokotemperaturowe austenityzowanie i obróbka na dolny bainit.
EN
The results of experimental study aimed at the development of steels for advanced structural applications, e.g. in the aircraft industry, were presented. For the quenched and tempered 40HSN3MWA steel, heat treatments alternative to the conventional quenching and tempering have been developed. The heat treatment involved high temperature austenitizing or transformation to microstructure of lower bainite, both leading to very high strength and fracture toughness.
2
Content available remote Odkształcalność plastyczna i anizotropia struktury taśm z nowych stali typu maraging
Pawlak S. J.
Stal, Metale & Nowe Technologie
|
2018
|
nr 11-12
64--68
PL
W pracy analizowano kierunkowość własności i struktury taśm cienkich wytworzonych ze stali X2NiMoTi19-4-1 i X1CrNiMoTi11-10-1, tj. odpowiednio bezkobaltowej stali typu maraging i stali odpornej na korozję umacnianej wydzieleniowo (SONK-UW). Do oceny anizotropii struktury stali i rozkładu wielkości ziarna wykorzystano mikroskop skaningowy z detektorem EBSD. Badane stale – pomimo całkowicie różnych składów chemicznych – mają bardzo zbliżone własności mechaniczne w stanie przesyconym oraz po starzeniu.
EN
The paper analyses the directionality of the tensile properties and microstructure of cold-rolled thin strips made of the X1NiMoTi19-4-1 Co-free maraging steel and the X1CrNiMoTi11-10-1 precipitation hardening stainless steel. The scanning electron microscopy EBSD technique was used to assess microstructural anisotropy and the grain size distribution. It was demonstrated that both steels – despite entirely different chemical compositions – exhibit very similar mechanical properties in the cold-rolled, annealed state and after age hardening.
3
Content available remote Cold worked high alloy ultra-high strength steels with aged martensite structure
Pawlak S. J., Krztoń H. J.
Journal of Achievements in Materials and Manufacturing Engineering
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2009
|
Vol. 36, nr 1
18-24
EN
Purpose: The study on structure-property relations of heavily cold worked and aged martensite in two high-alloy structural steels was presented. The aim was to understand properties of the sheet products better and thus extend applications of the newly developed cobalt-free maraging and precipitation hardening stainless steels. Design/methodology/approach: Mechanical tests were performed on cold rolled and aged specimens. Microstructures were analyzed using TEM and SEM. The crystallographic texture was analyzed by means of X-ray diffraction and ADC method. Findings: In the process of cold working and ageing both high alloy steels studied could develop yield strength in excess of 1600 MPa. The main strengthening mechanism was precipitation hardening, while work hardening contribution to the strength was very limited. Overaging commences after prolonged treatment above 500şC, and in both steels could be related to reverted austenite. The texture developed by cold working was the one known as rolling texture type. Research limitations/implications: In this study the advantage is taken of the high strength that is developed by cold working followed by ageing. Further research is needed for the sheet or strip produced by cold working and annealed before fabrication. Practical implications: The properties of the high alloy steels studied make them suitable for advanced sheet applications, e.g. as an airborne structural equipment. After welding, strength of the precipitation hardening steels could be largely restored by ageing, because their strength does not rely on strain hardening. Originality/value: Analysis of the cold worked properties, microstructure and texture, allowed for better understanding of the microstructure-property relationships in the low strain hardening high alloy sheet steels. The results obtained are of practical value for the development, production and manufacture of the ultra-high strength sheet steels.
4
Content available remote Rozwój metod ilościowej analizy wtrąceń niemetalicznych z zastosowaniem do ultraczystych stali wysokostopowych
Pawlak S. J., Maciosowski A., Gazdowicz J.
Prace Instytutu Metalurgii Żelaza
|
2008
|
T. 60, nr 4
58-60
PL
W oparciu o posiadane oprogramowanie do ilościowej analizy obrazu nowoczesnych mikroskopów świetlnych i skaningowych skorygowano metodyki ilościowej analizy wtrąceń niemetalicznych w zastosowaniu do ultraczystych stali wysokostopowych. Wykorzystano nowo pozyskane moduły oprogramowania do zautomatyzowanych pomiarów, przydatnych do analiz bardzo małej ilości cząstek z uwzględnieniem podziału na rodzaj cząstek (azotki, siarczki). Zaproponowano korekty do znormalizowanych metod ocen ilościowych wtrąceń stosowanych do wymienionych materiałów.
EN
Based on possessed software for quantitative analysis of the image from modern light and scanning microscopes, the methodologies for quantitative analysis of non-metallic inclusions used for ultra-pure high-alloy steels were corrected. T7ie newly acquired software modules for automated measurements, useful for analyses of very small amounts of particles taking into consideration the division into particle types (nitrides, sulphides), were used. Corrections to standardised methods for quantitative assessments of inclusions used for the above-mentioned materials were proposed.
5
Content available remote Microstructure, properties and hot deformability of the new maraging steels
Pawlak S. J., Zalecki W.
Journal of Achievements in Materials and Manufacturing Engineering
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2008
|
Vol. 29, nr 1
31-38
EN
Purpose: The effects of relevant metallurgical factors on the structure, fracture mode and properties of the high cobalt and cobalt free maraging steel has been studied. The aim was to better understand structure-property relations and enhance mechanical properties of the steels. To provide data needed for production and manufacturing technology, the high temperature deformability using physical simulation method was used. Design/methodology/approach: To study structure-property relation, broad range of the experimental techniques was used: quantitative metallography, X-ray diffraction phase analysis, transmission electron microscopy and SEM fractography. The flow properties in the range of hot working processes were determined by physical simulation approach, using Gleeble 3800 system. Findings: The cobalt-free maraging steel proved to be a valuable structural steel. At much higher fracture toughness it had only about 100 MPa lower yield stress, compared to that of high cobalt steel. Fracture surface morphologies were highly dependent on the steel grade and type of the mechanical test. The hot stress-strain characteristics were established for cobalt free maraging steel and compared to that of a stainless steel. Research limitations/implications: To fully evaluate potential field of applications, deeper comparative studies of the high cobalt and cobalt-free maraging steels are needed, particularly fracture modes and service properties of some parts. Practical implications: Very high mechanical properties and fracture toughness values obtained for the steels studied, make them suitable for advanced structural applications. The studies on the hot deformation behaviour of the steels are of practical value for the hot working process development. Originality/value: Detailed evaluation of the metallurgical purity, microstructure and fracture modes, allowed for better understanding of the microstructure-property relationships in selected high strength steels. The results obtained are of practical value for the development, production and manufacture of the high strength maraging steels with improved properties.
6
Content available remote Microstructure and properties of vacuum melted high cobalt and cobalt-free maraging steels
Pawlak S. J.
Journal of Achievements in Materials and Manufacturing Engineering
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2008
|
Vol. 27, nr 1
31-34
EN
Purpose: Steel cleanliness, microstructure and fracture mode have been studied, with the aim of enhancing mechanical properties and toughness of the high cobalt and cobalt-free maraging steels. Design/methodology/approach: To fully evaluate all relevant metallurgical factors affecting steel mechanical properties and toughness, broad range of the experimental techniques was used: quantitative metallography, X-ray diffraction, TEM and SEM fractography. Findings: Purity of the laboratory vacuum melted steels was similar to that of foreign industrial steels of the aircraft quality. It was showed that cobalt-free maraging steel could achieve properties comparable to the steel with very high cobalt content. Fracture surface morphologies were highly dependent on the steel grade and type of the mechanical test. In higher strength, the high cobalt steel fractures were generally more flat and more ductile than in the Co-free steel, particularly in the impact test. Research limitations/implications: Further comparative studies of the high cobalt and cobalt-free maraging steels are required on the properties, fracture modes and service properties of a selected parts. Practical implications: Very high mechanical properties and fracture toughness values obtained for the steels studied, are suitable for advanced structural applications. Originality/value: Detailed evaluation of the metallurgical purity, microstructure and fracture modes, allowed for better understanding of the microstructure-property relationships in selected high strength steels. The results obtained are of practical value for the development and production of the high strength steels with improved properties.
7
Content available remote Austenite stability in the high strength metastable stainless steels
Pawlak S. J.
Journal of Achievements in Materials and Manufacturing Engineering
|
2007
|
Vol. 22, nr 2
91-94
EN
Purpose: The aim of the present paper was to study the peculiarities of the austenite to martensite phase transformation (A-M), which is an essential step in the production technology of the high strength metastable stainless steels. Design/methodology/approach: The desired control over A-M transformation have been achieved by proper design of the steel chemistry, cold working and heat treatment. Findings: For a range of steel compositions, it was shown that severe cold working leads to fully martensitic structures. Alternatively, the deep refrigeration treatment or heating at about 750 degrees centigrade, are also effective in that respect. Subsequent ageing treatment of the deformed martensite, or martensite obtained by subzero treatment, develops interesting set of the mechanical properties. Research limitations/implications: To fully evaluate the properties of the steels further research is needed, particularly involved with the cold drawing and ageing response. Practical implications: The new metastable stainless steels could achieve properties making them competitive to some high strength steels and alloys - those with not so good combination of formability, strength and corrosion resistance. Originality/value: Revealed transformation behavior of the complex alloyed austenites makes an essential step in development of the high strength metastable stainless steels.
8
Content available remote Opracowanie i wdrożenie metodyki ilościowych badań metalograficznych z zastosowaniem cyfrowej analizy obrazu
Pawlak S. J., Maciosowski A., Janiczek J., Wiedermann J.
Prace Instytutu Metalurgii Żelaza
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2006
|
T. 58, nr 1
54-56
PL
Celem pracy było opracowanie i wdrożenie w laboratorium Instytutu współczesnych metod metalografii ilościowej w oparciu o nowy zestaw złożony z mikroskopu świetlnego, kamery cyfrowej i oprogramowania do cyfrowej analizy obrazu. Opracowane metodyki zostały zastosowane do rozwiązania praktycznych zadań metaloznawczych w zakresie pomiaru udziału objętościowego faz, wielkości ziarna i zawartości wtrąceń niemetalicznych.
EN
The purpose of the paper was to develop and implement modern quantitative metallography methods in Institute for Ferrous Metallurgy's laboratory based on a new unit comprising a light microscope, digital camera and digital image analysis software. These methodologies were used to solve practical physical metallurgy problems with regard to measurement of phase volume fraction, grain size and content of non-metallic inclusions.
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