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1

Effects of ageing heat treatment temperature on the properties of DMLS additive manufactured 17-4PH steel

Świetlicki Aleksander, Wlaczak Mariusz, Szala Mirosław, Turek Marcin, Chocyk Dariusz

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 4

art. no. e146237

EN

Additive manufacturing (AM) is a modern, innovative manufacturing method that enables the production of fully dense products with high mechanical properties and complex shapes that are often impossible to obtain by traditional methods. The 17-4PH grade steel is often applied where high mechanical performance is required. 17-4PH, or AISI 630, is intended for precipitation hardening, an operation that combines solution and ageing treatments and is used to significantly change the microstructure of the steel and enhance its mechanical properties. This study investigates the effect of precipitation hardening on the properties of 17-4PH steel. To examine microstructure and morphology, metallographic tests were performed together with phase composition and chemical composition analyses. Mechanical parameters were determined via Vickers hardness testing and the Oliver-Pharr method. Samples were fabricated using direct metal laser sintering (DMLS), which is one of the powder bed fusion methods. The use of a constant solution treatment temperature of 1040_C and different ageing temperatures made it possible to evaluate the effects of ageing temperature on the mechanical properties and microstructure of 17-4PH. The presence of face-centered cubic FCC g-austenite and body-centerd cubic BCC a-martensite structures were detected. The tests revealed that – similarly to the wrought material – the highest hardness of 382_10:3 HV0:2 was obtained after ageing at 450_C. The nanoindentation test showed the same H/E ratio for the sample after fabrication and after solution treatment at 0.016769, but this value increased after ageing to 127–157.5%. The sample aged at 450_C was characterized by the highest H/E ratio of 0.026367, which indicates the highest wear resistance of this material under employed treatment conditions. In general, the sample treated at 450_C showed the best performance out of all tested samples, proving to have the smallest grain size as well as high Vickers and nanoindentation hardness. On the other hand, the use of solution treatment led to reduced hardness and improved workability of the AM material.

2

The Effect of the Parameters of Robotic TIG Welding on the Microstructure of 17-4PH Stainless Steel Welded Joint

Nalborczyk-Kazanecka Agnieszka, Mrowka-Nowotnik Grażyna

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 1

339--344

EN

17-4PH stainless steel finds application in the aerospace industry owing to its good mechanical properties and corrosion resistance. In the literature, this steel is described as good for welding, but research shows that it may be problematic due to the formation of defects. In this study, the welded joints were made by the robotic TIG welding method with various welding speeds (2 and 3 mm/s). The joints were subjected to non-destructive testing and were free from defects. The microstructure was observed by light microscopy and scanning electron microscopy. Changes in the microstructure of the heat affected zone were observed and discussed. Based on the observation of the microstructure and the change in the hardness profile, the heat affected zone was divided into 4 characteristic regions. δ-ferrite and NbC were observed in the martensite matrix. The welded joints were subjected to heat treatment consisting of solution and aging in 550°C for 4 h. The microstructure of the heat affected zone become homogenized as a result of the heat treatment. The content of stable austenite in the welded joint after the heat treatment was about 3%.

3

Microstructural Evolution and Oxidation Behavior of Fe-4Cr-6Ti Ferritic Alloy with Fe2Ti Laves Phase Precipitates

Demirel Ahmet, Çetin Emre Can, Karakuş Ali, Ataş Mehmet Şahin, Yildirim Mehmet

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 3

827--836

EN

The microstructural properties and hardness of a model ternary Fe-4Cr-6Ti ferritic alloy aged at 800°C for 8, 16 and 24 h are investigated in detail. Fine Fe2Ti Laves phase particles precipitate in the α-Fe (ferrite) matrix phase after solutionizing and subsequent aging treatments. The size and amount of Fe2Ti precipitates gradually increase with increasing aging time. The magnetic measurements of the aged samples confirm the variations in the microstructural properties including the volume fraction of the constituent phases, and Ti content of the α-Fe matrix phase. The mean Vickers microhardness value also increases from 203.5 to 238.4 with increasing aging time from 8 to 24 h. In addition, the cyclic oxidation behavior of 24 h aged sample, which contains maximum amount of Fe2Ti precipitates, is also investigated in detail. X-ray diffraction analysis reveals that scale product is α-Fe2O3 (hematite). Significant scale spallation and void formation is observed on the surfaces of 24 h aged Fe-4Cr-6Ti sample oxidized at 500°C.

4

Use of the Precipitation Hardening to Improve the Properties of Combustion Engine Pistons Made of Eutectic Silumins

Trepczyńska-Łent Małgorzata, Műller K.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 4

77--81

EN

The study presents methods to be used for improving the performance parameters of car engine pistons made of EN AC-AlSi12CuNiMg alloy according to the PN-EN 1706: 2011. Pistons of slow sucking and turbocharged engines were researched. A solution heat and ageing treatments were applied according to four variants. Temperatures of the solution heat treatment were: 550 ±5°C; 510°C ±5°C; and alternate: 276 ±5°C/510 ±5°C. The solution time ranged from 6 min to 4 h. Temperatures of the ageing heat treatment were 20°C and 250°C, while the ageing time ranged from 1,5 to 3h. Natural ageing was performed in 5 days. Measurements of hardness HRB and the piston diameters were performed. An improvement in the performance parameters of combustion engines was observed. Three solution heat treatment and ageing variants, allowed to obtain the pistons with hardness equal/higher than pistons of the turbocharged engines. The test results confirmed the possibility of providing a piston with properties exceeding the high load parameters specified by the manufacturer. Further studies will make it possible to improve the effects of the proposed solutions.

5

The Precipitation Hardening of Continuous Ingots of AlSi2Mn and AlCu4MgSi Alloys

Wróbel T., Nuckowski P. M., Jurczyk P.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 2

181--186

EN

The paper presents the research results of the influence of the precipitation hardening on hardness and microstructure of selected Al-Si and Al-Cu alloys obtained as ϕ30 mm ingots in a horizontal continuous casting process. The ingots were heat treated in process of precipitation hardening i.e. supersaturation with subsequent accelerated or natural ageing. Moreover in the range of the study it has been carried out investigations of chemical constitution, microscopic metallographic with use of scanning electron microscope with EDS analysis system, and hardness measurements using the Brinell method. On basis of obtained results it has been concluded that the chemical constitution of the investigated alloys enables to classify them into Al alloys for the plastic deformation as EN AW-AlSi2Mn (alternatively cast alloy EN AC-AlSi2MgTi) and as EN AW-AlCu4MgSi (alternatively cast alloy EN AC-AlCu4MgTi) grades. Moreover in result of applied precipitation hardening has resulted in the precipitation from a supersaturated solid solution of dispersive particles of secondary phases rich in alloying element i.e. Si and Cu respectively. In consequence it has been obtained increase in hardness in case of AlSi2Mn alloy by approximately 30% and in case of AlCu4MgSi alloy by approximately 20% in comparison to the as-cast state of continuous ingots.

6

Wear resistance characteristics of thermo-chemically treated structural steels

Senatorski J., Tacikowski J., Mączyński P.

Tribologia

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2017

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nr 3

171--178

EN

The article presents results of investigations of wear resistance by friction, employing the “3 cylinder – cone” method, of selected structural steels subjected to given thermo-chemical treatment, i.e. nitriding, carburizing, and precipitation hardening after nitriding. The investigated steels were C45, 21NiCrMo2, 18HGT, and 41Cr4. These materials, after thermo-chemical treatment undergo metallurgical characteristics of diffusion layers formed on steel. It was observed that proportionality exists between their wear resistance and the value of surface unit loading. Moreover, the friction – wear properties of these layers exhibited certain differences, depending on their microstructure and chemistry.

PL

Artykuł ten przedstawia wyniki badań odporności na zużycie, wykorzystując metodę „3 wałeczki – stożek”, dotyczące wybranych stali konstrukcyjnych poddanych określonej obróbce cieplno-chemicznej, tj. azotowaniu, nawęglaniu i utwardzaniu wydzieleniowemu po azotowaniu. Badanymi stalami były: C45, 21NiCrMo2, 18HGT i 41Cr4. Stale te po obróbce cieplno-chemicznej podlegają ocenie metaloznawczej warstw dyfuzyjnych wytwarzanych na stali. Zauważa się ich proporcjonalną zależność pomiędzy odpornością na zużycie a wartością nacisku jednostkowego powierzchni. Jednakże własności tarciowo-zużyciowe wyraźnie różnią się, zależąc od ich mikrostruktury i budowy chemicznej.

7

Wpływ obróbki cieplnej na własności stopu AlSi11 konsolidowanego plastycznie z wiórów

Noga P., Wiewióra M., Wzorek A.

Mechanik

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2017

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R. 90, nr 7

621--623

PL

Przedstawiono wyniki badania prętów otrzymanych w procesie wyciskania współbieżnego z wiórów stopu AlSi11 pozostałych po procesie toczenia. Określono własności mechaniczne podczas jednoosiowej próby rozciągania oraz pomiaru twardości metodą Vickersa. Zbadano wpływ warunków starzenia na własności mechaniczne.

EN

The paper presents study results on AlSi11 alloy, which was obtained by extruding chips obtained from turning process. Mechanical properties from uniaxial tensile test and Vickers hardness test were determined. The influence of aging conditions on mechanical properties was invetsigated.

8

Modelling and simulation of core-shell precipitates under tensial loading using the cellular automata method

Staszczyk A., Debyser M., Sawicki J.

Mechanics and Mechanical Engineering

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2017

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Vol. 21, nr 3

443--452

EN

The equivalent truss method has been known for years as a numerical model used in problems with structural optimization. It is often implemented in computational algorithms based on cellular automation (CA). This method (CA) is highly versatile and allows the modelling of phenomena which occur in multiple dimensional scales, including material engineering issues. This paper describes a numerical model used to simulate the stress caused by the external load in a multi-phase material. The authors propose applying the algorithm in modelling the behavior of alloy materials following a thermal treatment which leads to precipitate hardening.

9

The influence of aging process parameters on selected mechanical properties of profiles from EN AW-6106 aluminium alloy

Romański P., Pilarczyk J. W., Wiewiórska S., Muskalski Z.

Hutnik, Wiadomości Hutnicze

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2017

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Vol. 84, nr 1

62--65

EN

The aim of this article was to analyze the influence of temperature and time period of artificially aging process on selected mechanical properties: Brinell hardness, yield strength, tensile strength, and elongation of hot extruded profiles from EN AW-6106 aluminum alloy. The result of the conducted research has pointed out that the temperature and the time of aging process had a significant effect on the selected mechanical properties. In the study it was found that the highest mechanical properties such as the yield strength and tensile strength for analyzed aluminum alloy were achieved for samples aged in temperature of 165°C for time period of 6 hours. The value of mechanical properties required be the standards for T6 temper were achieved after 2 hours of artificial aging in temperature of 165°C.

PL

Celem pracy była analiza wpływu temperatury i czasu procesu sztucznego starzenia na wybrane właściwości mechaniczne: twardość Brinella, umowną granice plastyczności, wytrzymałość na rozciąganie i wydłużenie wyciskanych na gorąco profili ze stopu aluminium EN AW-6106. Wyniki przeprowadzanych badań wykazały, że temperatura i czas procesu sztucznego starzenia ma istotny wpływ na wybrane do badań właściwości mechaniczne. W badaniach stwierdzono, że najwyższą wartość własności mechanicznych takich jak: umownej granicy plastyczności oraz wytrzymałości na rozciąganie uzyskano po przeprowadzonym procesie sztucznego starzenia w temperaturze 165°C przez czas 6h. Niezbędny poziom własności mechanicznych wymaganych przez normy dla stanu T6 osiągnięto już po dwóch godzinach procesu starzenia w temperaturze 165°C.

10

Study of the precipitation hardening process in recycled Al-Si-Cu cast alloys

Kuchariková L., Tillová E., Matvija M., Belan J., Chalupová M.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 1

397--403

EN

The formation of extremely small uniformly dispersed particles of a second phase within the original phase matrix during heat treatment changed material properties. Therefore the characterization of precipitation had been investigated using high resolution transmission electron microscopy (TEM) and electron diffraction of thin foils for an AlSi9Cu3 cast alloy. For investigation the hardening effect onto mechanical properties of aluminium cast was used heat treatment, which consisted from solution treatment at 515°C / 4 hours (h), followed by quenching into water with temperature 50°C and artificial aging using different temperatures 170°C and 190°C with different holding time 2, 4, 8, 16, and 32 hours. The observations of microstructure and substructure reveals that precipitation hardening has caused great changes in size, morphology and distributions of structural components, the formation of precipitates of Cu phases, and the change of mechanical properties as well.

11

Application of an equivalent truss model for determining the stress state in multi-phase materials with cellular automata method

Staszczyk A., Sawicki J.

Advances in Science and Technology. Research Journal

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2017

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Vol. 11, no 2

51--57

EN

The Cellular Automata represent a universal method of modelling and simulation. They enable the performance of calculations for even the most complex processes and phenomena. They are also used successfully in mechanical and material engineering. In this paper, the concept of application of the Cellular Automata method for simulating the behaviour of material under stress is presented. The proposed numerical algorithm created performs a number of calculations of local stress states in the structure of precipitation hardened material. The principle of its operation is based on the application of the equivalent truss model, which is often used in the optimisation and design of structures. In this paper, this model was used to simulate a system embodying a section of the material containing various phases with different mechanical properties.

12

Nowe staliwo ledeburytyczne o osnowie umacnianej wydzieleniowo

Pacyna J.

Prace Instytutu Odlewnictwa

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2016

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Vol. 56, no. 1

3--6

PL

Zaprojektowano nowe staliwo ledeburytyczne o osnowie umacnianej wydzieleniowo związkami międzymetalicznymi, którego skład chemiczny uzupełniono zbilansowanym węglem i dodatkiem około 4,25% V. Uzyskano skłonną do umacniania związkami międzymetalicznymi martenzytyczno-austenityczną osnowę z siatką ledeburytu na granicach krystalitów. Twardość (około 400 HV20) i praca złamania KV (około 3 J) nowego tworzywa są minimalnie większe od tych samych właściwości dotychczas stosowanego staliwa G200CrNiMo4-3-3, które głównie stosowane jest na walce bruzdowe w walcowniach średnich i dużych. O zastosowaniu w praktyce przemysłowej nowego staliwa zdecydują jego właściwości tribologiczne.

EN

A new ledeburite cast steel was designed based on a matrix precipitation hardened with intermetallic compounds of a chemical composition enriched by adding about 4.25% V totally balanced with carbon. A martensitic-austenitic matrix with a ledeburite network at the crystallite boundary prone to the strengthening effect with intermetallic compounds was obtained. Both hardness (about 400 HV20) and fracture energy KV (about 3 J) of the new material are only slightly superior to the same properties offered by the cast G200CrNiMo4-3-3 steel used so far for the section rolls operating in medium and large rolling mills. The applicability of the new cast steel in industrial practice will mainly depend on its tribological properties.

13

Analiza odporności na zużycie obrobionych cieplno-chemicznie stali konstrukcyjnych

Senatorski J., Tacikowski J., Mączyński P.

Inżynieria Powierzchni

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2016

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nr 2

31--35

PL

W artykule przedstawiono wyniki badań metaloznawczych oraz odporności na zużycie przez tarcie wybranych stali konstrukcyjnych poddanych azotowaniu, nawęglaniu oraz utwardzaniu wydzieleniowemu po azotowaniu. Ten ostatni proces okazał się wyjątkowo korzystny w porównaniu z nawęglaniem, jak również z samym azotowaniem.

EN

This article presents the results of the metallurgical and wear by friction resistance research of the selected constructional steels subjected to: nitriding, carburizing, and also precipitation hardening after nitriding. This last process has proved to be exceptionally advantageous when compared to both the carburizing and also to the nitriding itself.

14

The Influence of Aluminum on the Microstructure and Hardness of Mg-5Si-7Sn Alloy

Rzychoń T., Dybowski B.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 1

425--432

EN

Magnesium alloys due the low density and good mechanical properties are mainly used in the automotive and aerospace industry. In recent years, magnesium alloys are extensively developed for use in high temperatures (above 120°C). Among these alloys, magnesium alloys containing tin and silicon have large possibilities of application due to the formation of thermally stable intermetallic Mg2Sn and Mg2Si. In this paper the influence of aluminum and heat treatment on the on the microstructure and hardness of Mg-7Sn-5Si alloy is reported. It was found that the microstructure of Mg-7Sn-5Si alloy consist of α-Mg solid solution, Mg2Sn and Mg2Si compounds. Addition of 2 wt% of Al to Mg-7Sn-5Si alloy causes the formation of Al2Sn phase. Moreover, Al dissolves in the α-Mg solid solution. The solution heat-treatment of tested alloys at 500°C for 24 h causes the dissolve the Mg2Sn phase in the α-Mg matrix and spheroidization of Mg2Si compound. The Mg2Si primary crystals are stable at solution temperature. After ageing treatment the precipitation process of equilibrium Mg2Sn phase was found in both alloys. The addition of aluminum has a positive effect on the hardness of Mg-7Sn-5Si alloy. In case of Mg-5Si-7Sn-2Al alloy the highest hardness was obtained for sample aged for 148 h at 250°C (88 HV2), while in case of Al-free alloy the highest hardness is 70 HV for material aged for 148 h at 250°C.

15

Precipitation Processes during Non-Isothermal Ageing of Fine-Grained 2024 Alloy

Kozieł J., Błaż L., Włoch G., Sobota J., Lobry P.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 1

169--176

EN

Mechanical alloying and powder metallurgy procedures were used to manufacture very fine-grained bulk material made from chips of the 2024 aluminum alloy. Studies of solution treatment and precipitation hardening of as-received material were based on differential scanning calorimetry (DSC) tests and TEM/STEM/EDX structural observations. Structural observations complemented by literature data lead to the conclusion that in the case of highly refined structure of commercial 2024 alloys prepared by severe plastic deformation, typical multi-step G-P-B →θ” →θ’ →θ precipitation mechanism accompanied with G-P-B →S” →S’ →S precipitation sequences result in skipping the formation of metastable phases and direct growth of the stable phases. Exothermic effects on DSC characteristics, which are reported for precipitation sequences in commercial materials, were found to be reduced with increased milling time. Moreover, prolonged milling of 2024 chips was found to shift the exothermic peak to lower temperature with respect to the material produced by means of common metallurgy methods. This effect was concluded to result from preferred heterogeneous nucleation of particles at subboundaries and grain boundaries, enhanced by the boundary diffusion in highly refined structures. Transmission electron microscopy and diffraction pattern analysis revealed the development of very fine Al4C3 particles that grow due to the chemical reaction between the Al matrix and graphite flakes introduced as a process control agent during the preliminary milling of chips. Al4C3 nano-particles are formed at high temperatures, i.e. during hot extrusion and the subsequent solution treatment of the samples. Highly refined insoluble particles such as aluminum carbide particles and aluminum oxides were found to retard recrystallization and reduce recovery processes during solution treatment of preliminarily milled materials. Therefore, the as-extruded material composed of a milled part and chip residuals retained its initial bimodal structure in spite of solution heat treatment procedures. This points to a high structural stability of the investigated materials, which is commonly required for new technologies of high-strength Al-based materials production.

16

Effect of the Combined Heat Treatment and Severe Plastc Deformation on the Microstructure of Cunisi Alloy

Głuchowski W., Rdzawski Z., Sobota J., Domagała-Dubiel J.

Archives of Metallurgy and Materials

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2016

|

Vol. 61, iss. 2B

1207--1214

EN

The aim of this work was to study the microstructure and functional properties of CuNi2Si1 alloy. The material was prepared classically by melting, casting, hot rolling and cold rolling. The obtained strips were processed with combined operations of supersaturation, ageing and one of the intensive deformation method - repetitive corrugation and straightening. The efficiency of RCS operation in shaping of functional properties in precipitation hardened copper alloys depends not only on tool geometry and operating parameters but also on whether and at what stage of strip production the supersaturation operation was applied. Application of the supersaturation before RCS operation broadens the potential to shape the set of functional properties. Comparable functional properties of the precipitation hardened copper alloy strips can be reached without application of the supersaturation operation in their manufacturing processes. The process of RCS applied after annealing, and the potentially slightly lower mechanical properties would be compensated by higher electrical conductivity.

17

Badania zmęczeniowe na zginanie stopów PA6 i PA7 nieutwardzonych i po utwardzaniu wydzieleniowym

Rozumek D., Hepner M., Faszynka S.

Mechanik

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2015

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R. 88, nr 3

246--249

PL

Przedstawiono wyniki badań doświadczalnych rozwoju pęknięć zmęczeniowych i prędkości wzrostu pęknięć zmęczeniowych przy cyklicznym zginaniu próbek ze stopów aluminium PA6 i PA7 bez utwardzenia wydzieleniowego i po nim. Badania przeprowadzono na maszynie zmęczeniowej MZGS-100, w zakresie wysokiej liczby cykli, przy współczynniku asymetrii cyklu R = −1. Rozwój pęknięć zmęczeniowych mierzono na powierzchni bocznej próbek za pomocą mikrometru i lunety o powiększeniu 25×, z dokładnością nie mniejszą niż 0,01 mm. Wyniki badań doświadczalnych opisano na wykresach prędkości wzrostu pęknięć zmęczeniowych w funkcji zakresu współczynnika intensywności naprężenia ΔK za pomocą związku Parisa. Związek ten w sposób zadowalający opisuje wyniki uzyskane doświadczalnie.

EN

Presented are results of experimental tests of the fatigue crack development and crack growth rate under cyclic bending of the PA6 and PA7 aluminum alloy specimens in non-hardened and in precipitation hardened condition. The tests were performed on the fatigue test stand MZGS-100 in the high cycle fatigue regime for the stress ratio R = −1. The fatigue crack growth was measured on the side surface of specimens with use the micrometer and the microscopic telescope of 25-time magnification, with accuracy reaching 0.01 mm. The test results were described on graphs of the fatigue crack growth rate versus changes of the stress intensity factor range ΔK with use of the Paris equation. This relationship satisfactorily describes the results obtained experimentally.

18

Wpływ prędkości procesu ciągłego odlewania i walcowania na strukturę i własności przewodowego stopu Al-Mg-Si

Osuch P., Smyrak B., Knych T.

Hutnik, Wiadomości Hutnicze

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2013

|

Vol. 80, nr 1

74--76

PL

Utwardzane wydzieleniowo stopy aluminium serii 6XXX (Al-Mg-Si), z uwagi na właściwości takie jak: niska masa właściwa, wysokie własności wytrzymałościowe, dobra odporność korozyjna, a także relatywnie niska rezystywność, znajdują zastosowanie jako materiał do wytwarzania przewodów elektroenergetycznych. Druty z przewodowych stopów Al-Mg-Si wytwarzane są z walcówki otrzymywanej w linii ciągłego odlewania i walcowania. W artykule przedstawiono wyniki badań wpływu prędkości odlewania i walcowania na własności i strukturę walcowanego pasma.

EN

A precipitation hardened 6XXX series aluminum alloys (Al-Mg-Si), due to a properties, such as low specific weight and high mechanical properties, good corrosion resistance, and a relatively low resistivity, can be used as material for the manufacture of power cables. The Al-Mg-Si conductor alloy wires are produced from wire rod, obtained in continuous casting and rolling line. This paper presents results of research of influence of casting and rolling velocity in the Continuus-Properzi line on properties and structures of the rolled strip.

19

Structure and mechanical properties of Al-Li alloys as cast

Augustyn-Pieniążek J., Adrian H., Rzadkosz S., Choroszyński M.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 2

5--10

EN

The high mechanical properties of the Al-Li-X alloys contribute to their increasingly broad application in aeronautics, as an alternative for the aluminium alloys, which have been used so far. The aluminium-lithium alloys have a lower specific gravity, a higher nucleation and crack spread resistance, a higher Young’s module and they characterize in a high crack resistance at lower temperatures. The aim of the research planned in this work was to design an aluminium alloy with a content of lithium and other alloy elements. The research included the creation of a laboratorial melt, the microstructure analysis with the use of light microscopy, the application of X-ray methods to identify the phases existing in the alloy, and the microhardness test.

20

New Nano-Precipitates Hardened Steels of Wide Range of Strength and Toughness and High Resistance to Piercing With Projectiles

Marcisz J., Garbarz B., Adamczyk M., Wiśniewski A.

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

|

2012

|

Vol. 3, Nr 4 (10)

39-54

EN

Results of tests of mechanical properties and resistance to perforation with small-calibre armour-piercing projectiles for new designed grades of nano-precipitates hardened steels have been presented. The results comprise of mechanical properties essential for materials used in armour and microstructure which influences the mechanisms of piercing. Plate segments of high-alloyed maraging steels and low-carbon Ni-Mo steels were produced using semi-industrial lines for melting, casting and thermo-mechanical treatment. Plate segments were produced with the use of different parameters of final heat treatment in order to achieve a wide range of mechanical properties. Preliminary assessment of the protection capability concerning piercing was carried out based on the results of firing tests with 12.7 mm B-32 incendiary projectiles at square steel plates of 50÷150 mm in dimension and of 5÷10 mm in thickness placed on an RHA (Armox 500T and Armox 600T) "witness" plate. A minimal thickness of plates which protected the "witness" plate and did not fragment was determined. The microstructure in the area of the projectile impact was examined. The usability of newly designed grades of steel in layered armour and the possibilities of the production of these plates from the steel in domestic steel plants were pointed out.