Wyniki wyszukiwania - BazTech

1

A micro-cooled high-strength weld for heavy transport means

Węgrzyn Tomasz, Szczucka-Lasota Bożena, Szymczak Tadeusz, Łazarz Bogusław, Piwnik Jan

Transport Problems

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2024

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T. 19, z. 1

83--96

EN

This paper focuses on the technical problem of repairing the main operating elements of heavy vehicles (semitrailers, dumps, and drums). If these vehicles are in service, significant changes in work schedules can occur, and costs can be generated immediately. Therefore, using the correct technology for repairs is crucial to minimizing financial and logistic difficulties. The article aims to analyze the mechanical properties of an MMA (Manual Metal Arc) welding (covered electrodes) joint made of Hardox 450 steel. This kind of material has a martensitic microstructure, which is difficult to weld because of changes in the components to the other ones during the joint process. Other inconveniences are related to the different chemical composition of steel and covered electrodes, their mechanical resistance, and thermodynamic conditions (consisting of the pre-heating temperature and the cross-pass temperature). Therefore, the joint quality should be determined using a few methods. In this case, NDT (magnetic and radiographic tests) and DT (microstructural analysis and static as well as fatigue tests) were used. All obtained results have enabled the proposed guides for the MMA welding of the steel grade. This is indicated as follows: (1) the method of bevelling the sheets before welding should be used, (2) pre-heating is necessary at temperature levels of 100 C and 125 C, and (3) the recommended interstitial temperature is between 170 C and 200°C.

2

The Investigation on flexural performance of prestressed concrete-encased high strength steel beams

Wang Jun, Jiao Yurong, Cui Menglin, Yang Wendong, Fang Xueqi, Yan Jun

Archives of Civil Engineering

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2024

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Vol. 70, nr 1

405--420

EN

This paper reports an experimental on the flexural performance of prestressed concrete-encased high-strength steel beams (PCEHSSBs). To study the applicability of high-strength steel (HSS) in prestressed concrete-encased steel beams (PCESBs), one simply supported prestressed concrete-encased ordinary strength steel beam (PCEOSSB) and eight simply supported PCEHSSBs were tested under a four-point bending load. The influence of steel strength grade, I-steel ratio, reinforcement ratio and stirrup ratio on the flexural performance of such members was investigated. The test results show that increasing the I-steel grade and I-steel ratio can significantly improve the bearing capacity of PCESB. Increasing the compressive reinforcement ratio of PCEHSSB can effectively improve its bearing capacity and ductility properties, making full use of the performance of HSS in composite beams. Increasing the hoop ratio has a small improvement on the load capacity of the test beams; setting up shear connectors can improve the ductile properties of the specimens although it does not lead to a significant increase in the load capacity of the combined beams. Then, combined with the test data, the comprehensive reinforcement index considering the location of reinforcement was proposed to evaluate the crack resistance of specimens. The relationship between the comprehensive reinforcement index and the crack resistance of specimens was given.

3

Experimental study of a new type of high-strength monolithic square-section concrete columns with spiral stirrups

Xianchao Zheng, Liyun Fan, Zhao Jun

Archives of Civil Engineering

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2023

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Vol. 69, nr 4

319--337

EN

In this paper, four full-scale concrete columns with high-strength spiral stirrups (HSSS) are constructed and tested under low-cycle repeated loading. The specimens consisted of two cast-in-place columns and two precast concrete columns encased by a partly square steel pipe and bolt bars. The structural analysis of the HSSS columns of precast concrete conducted here is novel, and past experimental data for this are not available. To assess the seismic behavior and failure mechanisms of the new connections, quasi-static tests were carried out on columns prefabricated with them and cast-in-place specimens. The responses of all columns were compared, and the results showed that the failure modes of all columns are the large eccentric damage, and the destruction of all specimens occur at the column foot. The anti-seismic property of the precast HSSS concrete columns was comparable to that of the HSSS cast-in-place columns. A comparison of such performance parameters as energy dissipation and coefficient of ductility revealed that the precast HSSS concrete columns are suitable for use in earthquake zones.

4

Tailoring the mechanical properties of austempered low‑carbon ferritic-bainitic/martensitic dual‑phase steel

Motallebi Reza, Mirzadeh Hamed

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 1

art. no. e32, 2023

EN

A simple heat treatment of austenitization followed by austempering was proposed to obtain ferritic-bainitic/martensitic dual-phase (DP) microstructure with ~ 18% bainite and ~ 30% martensite in low-carbon steel, which provides a promising way for processing of low-cost high-performance advanced high-strength steels (AHSSs) with improved strength-ductility trade-off, tensile toughness, and fracture behavior. The processed bainite-aided DP steel exhibited high yield stress and high ultimate tensile strength while maintaining high total elongation to failure, which were beyond the expected trends for conventional steels, ferritic-martensitic DP steels, and ferritic-bainitic DP steels. The continuous yielding behavior (with the disappearance of the yield point phenomenon) and more ductile fracture surface appearance were also remarkable. Accordingly, besides grain refinement by cold rolling and intercritical annealing, the present work proposed an alternative way for processing high-performance DP steels.

5

Overall buckling performance of high strength steel welded I-sections under combined axial compression and bending

Huang Bin, Zhang Wen-Fu

Archives of Civil Engineering

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2022

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Vol. 68, nr 3

369--384

EN

This paper presents a numerical investigation into the high strength steel (HSS) welded I-section overall buckling performance with respect to the major axis under combined axial compression and bending. The validation of FE models compared with the existing test data to verify the appropriateness of the element division and boundary condition was firstly conducted. In line with the FE arrangement verified, separate 890 numerical models, covering a broader range of eight steel grades (460 MPa, 500 MPa, 550 MPa, 620 MPa, 690 MPa, 800 MPa, 890 MPa and 960 MPa), different overall slenderness and various eccentricities were designated. Subsequently, the comparison of the resistance prediction codified design rules in EN 1993-1-1, ANSI/AISC 360-10 and GB50017-2017 was preferentially operated, by the instrumentality of the normalized axial compression-bending moment curves. The results graphically revealed that, the provision given in ANSI/AISC 360-10 concerned in the present work was the most loose, whereas, the corresponding content set out in EN 1993-1-1 and GB50017-2017 was relatively on the safe side. Taking account of the FE results, the conservative shortcomings of the considered rules in EN 1993-1-1 and GB50017-2017 were further highlighted. Especially, the disparity of EN 1993-1-1 and numerical results was higher to 27%, from the perspective of a definition given in the present work. In contrast, the provision in ANSI/AISC 360-10 yielded a relatively accurate prediction, on average. Based on the numerical program, an alternative formula for the HSS welded I-section beam-columns with a general expression form was sought, which intimately reflected the effect of overall slenderness.

6

Cold unidirectional/cross‑rolling of austenitic stainless steels: a review

Mohammadzehi Sara, Mirzadeh Hamed

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 3

art. no. e129

EN

The effects of cold unidirectional/cross-rolling on the development of substructure, strain-induced martensitic transformation, crystallographic texture (preferred orientation), and mechanical properties, as well as the microstructure after subsequent annealing of metastable austenitic stainless steels were overviewed. First, the deformed state was discussed. Compared to unidirectional rolling, it was revealed that cross-rolling leads to the formation of a greater amount of deformation-induced martensite, which is related to the generation of numerous intersecting shear bands and nano-twins, as well as a higher dislocation density in the austenite phase (activation of higher number of slip/twinning systems). It was concluded that these effects are more pronounced at low reductions in thickness. Regarding texture evolution, cross-rolling tends to strengthen the Brass component in the retained austenite phase. Subsequently, the mechanical properties were reviewed, where it was concluded that a more rapid work-hardening and higher strength/hardness at low strains can be obtained due to the effects of cross-rolling on the microstructure. Moreover, while the effects of cross-rolling on the strength at high rolling reductions might not be significant, it is possible to decrease the anisotropy of the sheet due to the alternate change in the rolling direction. Afterward, the annealing of cold-rolled sheets was discussed. It was deduced that cross-rolling might be used for more intense grain refinement based on the thermomechanical processing of cold-rolling and reversion/recrystallization annealing, where the activation of greater number of slip systems, higher dislocation density, and greater martensite content in the deformed state are responsible in this regard. Finally, the suggestions for future works were proposed.

7

Microstructure and residual stress analysis of Strenx 700 MC welded joint

Trško Libor, Lago Ján, Jambor Michal, Nový František, Bokůvka Otakar, Florková Zuzana

Production Engineering Archives

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2020

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Vol. 26, Iss. 2

41--44

EN

High strength low alloy (HSLA) steels are a new generation of plain carbon steels with significantly improved mechanical properties while maintaining good weldability with common commercial techniques. Residual stress and microstructural analysis of welded HSLA Strenx 700 MC was carried out in this research. Results have shown that the welding process causes significant grain coarsening in the heat affected zone. The microstructural changes are also accompanied with creation of tensile residual stress field in the weld metal and heat affected zone, reaching up-to depth of 4 mm. Tensile residual stresses are well known for acceleration of fatigue crack initiation and together with coarse grains can lead to significant decrease of the fatigue properties of the welded structure.

8

Assessment of the possibility of the laser welding of high strength steel having a yield point of 1100 MPa

Tuz Lechosław, Sulikowski Krzysztof

Biuletyn Instytutu Spawalnictwa w Gliwicach

|

2019

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Vol. 63, No. 6

25--31

EN

The article presents selected results of technological tests involving the welding of high-strength steel (with a guaranteed yield point of 1100 MPa) using a robotic laser beam welding station. The joints made in the tests were subjected to visual, macroscopic and microscopic tests as well as to hardness measurements. The obtained results revealed the presence of martensitic-bainitic structure in the cross section of the welded joint and the presence of a narrow zone characterised by low hardness (softened zone).

PL

Przedstawiono wybrane wyniki z prób technologicznych spawania stali o wysokiej wytrzymałości (gwarantowanej granicy plastyczności 1100 MPa) przy wykorzystaniu zrobotyzowanego stanowiska do spawania wiązką laserową. Wykonane złącza poddawano badaniom wizualnym, makroskopowym i mikroskopowym oraz pomiarom twardości. Uzyskane wyniki wskazują na występowanie martenzytyczno-bainitycznej struktury w przekroju poprzecznym złącza spawanego oraz występowaniu wąskiej strefy o niskiej twardości (strefy zmiękczenia).

9

Minimum value approach for modelling of the buckling resistance of welded I-section high strength steel columns

Gajewski M. D., Giżejowski M. A., Szczerba R. B.

Archives of Civil Engineering

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2019

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Vol. 65, nr 4

113--126

EN

The paper deals with determination of flexural resistance buckling curves for welded I-section steel members made of high strength steel (S 690). In the paper the previously proposed BF analytical model is used for approximation of FEM results obtained using moderately large deformation shell theory and ABAQUS/Standard software. Final formulation of flexural resistance buckling curves is possible through the use of the Merchant-Rankine-Murzewski approach adopted extensively in the authors’ previous papers. For nonlinear optimization, which is needed for analytical model parameters determination, the Wolfram Mathematica package is used. Obtained results for S 690 steel are presented against the results for S 355 steel.

PL

Celem artykułu jest wyznaczenie krzywych wyboczeniowych w przypadku spawanych elementów ściskanych wykonanych ze stali S 690. Rozważane zagadnienie stanowi kontynuację pracy [3], gdzie analogiczne zagadnienie rozważano dla stali S 355. Zastosowano, zweryfikowane w [3] jako najbardziej wiarygodne, podejście analityczne Best Fit z uwzględnieniem metody randomizacji Merchanta-Rankine’a-Murzewskiego. Kalibrację sformułowania analitycznego przeprowadzono na podstawie wyników symulacji MES z programu ABAQUS. Wyniki obliczeń numerycznych posłużyły do wyznaczenia parametrów materiałowych zaproponowanego modelu analitycznego. Wyznaczenie parametrów materiałowych było możliwe dzięki zastosowaniu metod optymalizacji nieliniowej i pakietu Wolfram Mathematica. Elementy ściskane modelowano w MES stosując teorię powłok dużych deformacji oraz modele konstytutywne sprężysto-plastyczności ze wzmocnieniem izotropowym. Naprężenia pospawalnicze modelowano poprzez wstępne samozrównoważone pole naprężeń rezydualnych. Pole naprężeń rezydualnych określone było przez dwa parametry: ψten i ψcom odpowiednio dla strefy rozciąganej i strefy ściskanej. Parametr naprężenia rezydualnego ψten jest utrzymywany na stałym poziomie dla różnych historii wymiany ciepła przy spawaniu. W konsekwencji tylko ψcom jest dalej uważany za zmienną. W analizie przyjęto wartości dyskretne z zakresu od 0.1 do 0.5, uwzględniając różne historie obciążenia termicznego wynikającego z przebiegu procesu spawania.

10

Effect of Welding Parameters on the Structure, Mechanical Properties and Crack Resistance of Welded Joints Made of Steel 14HGN2MDAFB

Markaszowa L. I., Poznjakow W. D., Berdnikowa E. N.

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2018

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Vol. 62, No. 2

41--49

EN

The article presents test results concerning the structure and the phase composition of the weld and HAZ metal of welded joints made of high yield point (above 700 MPa) steel 14HGN2MDAFB using the mechanised welding method. The tests involved the analytical assessment of the effect of structural parameters on the mechanical properties (Re, К*1C) of welded joints as well as the determination of the role of structural factors (phase composition, grain structure, subgrain structure and dislocation) in terms of changes in local internal stresses (τj), i.e. crack formation concentrators. The tests enabled the identification of optimum technological conditions ensuring the obtainment of high quality and reliable welded joints of structures characterised by high mechanical properties and crack resistance.

PL

Przedstawiono wyniki badań struktury i składu fazowego metalu spoin oraz strefy wpływu ciepła połączeń spawanych stali o wysokiej wytrzymałości 14ХГН2МДАФБ (o granicy plastyczności ponad 700 MPa), wykonanych za pomocą spawania zmechanizowanego. Przeprowadzono analityczne oceny wpływu parametrów strukturalnych na własności mechaniczne (Re, К*1с) połączeń spawanych. Określono rolę czynników strukturalnych (składu fazowego, struktur ziarnowej, podziarnowej i dyslokacyjnej) w zmianie poziomu lokalnych naprężeń wewnętrznych (τj) – koncentratorów powstawania pęknięć. Określono optymalne warunki technologiczne zapewniające uzyskanie jakościowych i niezawodnych połączeń spawanych z punktu widzenia tworzącej się struktury, która zapewnia wysokie wskaźniki własności mechanicznych i odporności na pękanie połączeń spawanych.

11

Assessment of Mechanical Properties of Laser Beam Welded Joints Made of Steel Strenx S700MC Subjected to High Impact Load

Prochenka P., Makowska K., Janiszewski J.

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2018

|

Vol. 62, No. 2

51--60

EN

The article assesses the strength and ductility of laser welded joints made of steel Strenx S700MC. The assessment was based on tests results concerning the material structure, hardness as well as quasi-static and dynamic tensile tests. The dynamic tests were performed using the tensile split Hopkinson pressure bar technique and strain rates of 103 s-1. The obtained results revealed that the strength of joints under quasi-static and dynamic tensile test conditions were high and similar, yet their ductility significantly deteriorated under the impact load.

PL

W artykule dokonano oceny wytrzymałości i ciągliwości złączy spawanych laserowo wykonanych ze stali Strenx S700MC na podstawie wyników badań struktury, rozkładu twardości oraz quasi-statycznej i dynamicznej próby rozciągania. Badania dynamiczne na rozciąganie z szybkością odkształcania rzędu 103 s-1 wykonano za pomocą techniki dzielonego pręta Hopkinsona. Uzyskane wyniki wykazały, że o ile wytrzymałość złączy w warunkach quasi-statycznego i dynamicznego rozciągania jest wysoka i zbliżona, to ich ciągliwość znacząco pogarsza się pod wpływem udarowego obciążenia.

12

Evaluation of microstructure and selected mechanical properties of laser beam welded S690QL high-strength steel

Tuz L.

Advances in Materials Science

|

2018

|

Vol. 18, nr 3(57)

34--42

EN

The paper presents results of microstructure and mechanical properties investigation of laser beam welded high-strength steel. Material for test was non-alloyed steel with yield strength of 690 MPa after quenching and tempering in delivery condition. Research carried out on the butt-welded joints shows fine-grain martensitic-bainitic structure of base metal and in the weld. Investigations of mechanical properties revealed the softened zone in HAZ where the hardness decrease without microstructural changes was observed. Moreover, an influence of softened zone and HAZ width on impact strength was observed where the occurrence of lower hardness led to fracture path deviation phenomenon.

13

Welding of High Strength Toughened Structural Steel S960QL

Madej K., Jachym R.

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2017

|

Vol. 61, No. 2

6--16

EN

The article discusses the effect of the thermal conditions applied during the MAG welding of steel S960QL and the mutual annealing of runs on the mechanical properties as well as on the macro and microstructure of welded joints made using various values of cooling time t8/5. The research described in the article also involved the comparison of the above-named results with those obtained during a thermal simulation. In addition, the article presents the test results concerning the examination of the coarse and fine-grained areas of the HAZ of welded joints. The test results made it possible to optimise the value of cooling time t8/5 when welding steel S960QL.

PL

Omówiono wpływ warunków cieplnych spawania stali S960QL metodą MAG oraz wzajemnego wyżarzania ściegów na własności mechaniczne oraz makro- i mikrostrukturę złączy spawanych, wykonanych z zastosowaniem różnych czasów chłodzenia t8/5, a następnie porównano te wyniki z rezultatami prób symulacji cieplnej. Przedstawiono również wyniki badań obszaru grubo- i drobnoziarnistego strefy wpływu ciepła złączy spawanych. Wyniki badań umożliwiają optymalizację czasu chłodzenia t8/5 spawania stali S960QL.

14

Spawanie laserowe nowoczesnej stali o wysokiej wytrzymałości Strenx 1100 MC

Kurc-Lisiecka A., Jurczyk R., Lisiecki A., Lis R., Ślizak D.

Stal, Metale & Nowe Technologie

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2016

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nr 3-4

52--57

PL

W artykule opisano wyniki badań wpływu parametrów procesu spawania laserowego nowego gatunku stali konstrukcyjnej o wysokiej wytrzymałości Strenx 1100 MC na jakość i właściwości mechaniczne złączy doczołowych o grubości 5,0 mm. Próby spawania wykonano za pomocą lasera dyskowego o średnicy ogniska wiązki laserowej 200 μm, techniką bez materiału dodatkowego. Badania wykazały, że możliwe jest zapewnienie poprawnego kształtu spoiny o drobnoziarnistej strukturze i wąskiej strefie wpływu ciepła. Jednak z uwagi na wyraźny spadek twardości w strefie wpływu ciepła, nawet przy stosunkowo niskich energiach liniowych spawania laserowego w zakresie od 130 do 200 J/mm, złącza próbne charakteryzują się niższą wytrzymałością na rozciąganie oraz udarnością na poziomie ok. 60% w porównaniu do materiału rodzimego.

EN

The article describes the results of the research on the influence of laser welding parameters of the new grade structural high-strength steel Strenx 1100 MC on the quality and mechanical properties of 5.0 mm thick butt joints. The tests of welding have been conducted by the means of a disk laser with a beam spot diameter of 200 μm, applying the autogenous technique, i.e. without the additional material. The results have shown that it is possible to provide a proper shape of the weld of fine-grained structure and narrow heat affected zone. However, due to the significant drop of hardness in the heat affected zone, even at relatively low energy inputs of laser welding in the range of 130 to 200 J/mm, the test joints are characterized by lower tensile strength and toughness at the level of about 60% as compared to the base material.

15

The influence of welding heat input on the microstructure of joints of S1100QL steel in one-pass welding

Nowacki J., Sajek A., Matkowski P.

Archives of Civil and Mechanical Engineering

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2016

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Vol. 16, no. 4

777--783

EN

Microstructure transformations of a welded joint of the of quenched and tempered advanced high-strength S1100QL steel in relation to the heat input and its effect on the strength of the joint. The gas metal arc welding method was used with varying values of the heat input in the range from 5.5 to 7.1 kJ/cm. Metallographic examination, hardness, impact strength, and tensile strength tests were carried out. Innovative methodology of welding impact test using drop tower impact resistance tester, has been applied. Joints with strength higher than that of welded steel were created. The amount of heat input necessary to produce joints of S1100QL steel whose strength would be higher than that of parent material was determined. The advantages of using S1100QL steel were indicated and a method of one-pass welding that allows for production of joints of optimum strength parameters with the use of mismatched filler metals was presented. As the result of detailed weld cracking dynamics analysis of the S1100QL steel the course of joint deformation was determined as a function of time, loading force and impact energy. It was found that the dynamically loaded samples welded with lower heat input display higher limit of elasticity, which is manifested by higher loading forces and longer deformation time.

16

Structural performance of rectangular section confined by squared spirals with no longitudinal bars influencing the confinement

Lee J. M., Kim Y. S., Kim S. W., Park J. H., Kim K. H.

Archives of Civil and Mechanical Engineering

|

2016

|

Vol. 16, no. 4

795--804

EN

Structural performance of rectangular concrete section confined by squared spirals was investigated. Through the uni-axial compression test using concrete prisms with squared spirals and without longitudinal bars, the enhancement of strength and deformation capacity of rectangular concrete section was scrutinized. By the experimental observations on the properties of lateral expansion of concrete prism, a moment of reaching the axial peak stress in section was predicted in a good accuracy. Qualitative relationships between the structural performance (the enhancement of strength and deformation capacity) of concrete prism and confinement efficiency were studied. Also, for the effective use of normal- and high-strength lateral reinforcement, a design implication using the qualitative relationship of the tensile stress in lateral reinforcement at failure of concrete prism with parameters was proposed.

17

Temper Bead Welding of S420G2+M Steel in Water Environment

Fydrych D., Świerczyńska A., Rogalski G., Łabanowski J.

Advances in Materials Science

|

2016

|

Vol. 16, nr 4(50)

5--16

EN

The article presents the idea of the use of Temper Bead Welding (TBW) technique to improve the weldability of high strength steel at underwater wet welding conditions. Wet welding method with the use of covered electrodes is described. This work shows results of metallographic examinations and hardness measurements of samples of S420G2+M steel with weld beads performed under water. It has been shown that Temper Bead Welding technique may provide a way to reduce the hardness of the welds, thus is a useful method for improving weldability of high strength steel welded in underwater conditions. The optimum overlap of weld beads (pitch) was set of 55÷100%.

18

Innovations in forming technologies

Kurka P., Schieck F.

Archives of Materials Science and Engineering

|

2014

|

Vol. 65, nr 2

72--76

EN

Purpose: of this paper is the research of implementation of lightweight materials (aluminium, magnesium) as an important contribution for significant weight savings. Design/methodology/approach: Higher process stability, improved material exploitations, and generall shortening of process chains are the most important aims of Fraunhofer IWU. The requirements of the future car ask for lightweight construction concepts, in which materials, design, and manufacturing processes harmonize optimally. Therefore, Fraunhofer IWU researches on forming and joining technologies in order to achieve the optimum usage of high-strength steels, aluminium, magnesium, and fiber composite materials. Findings: New forming technologies as press hardening or electromagnetic forming (EMF) bring positive effects by resource efficiency and energy savings. When developing new materials, it is important to design the whole process chain according to the specific material properties. Practical implications: Press hardening offers an effective method of forming high strength steels. EMF is a high-speed forming technology applicable for shaping, joining, and cutting electrically conductive sheet metal or hollow profile components. Originality/value: The usage of lightweight materials is only reasonable when their mechanical characteristics such as stability, stiffness, and temperature resistance are better than those of classic steel. The same is true for the material and production costs.

19

Wpływ procesów cięcia termicznego i strumieniem wody na właściwości i jakość powierzchni ciętych stali niskostopowych o wysokiej granicy plastyczności

Górka J., Skiba R.

Przegląd Spawalnictwa

|

2013

|

R. 85, nr 2

11-18

PL

W artykule opisano wpływ procesu cięcia strumieniem tlenu, plazmą powietrzną HD, laserem oraz strumieniem wody na jakość powierzchni stali obrobionej termomechanicznie S 700MC oraz ulepszonej cieplnie S 690QL o grubości 10 mm. Ocenie poddano jakość powierzchni pocięciu (odchyłkę prostopadłości, chropowatość powierzchni, kąt ukosu), szerokość szczeliny cięcia, sposób przebijania oraz zmiany strukturalne i zmiany twardości zachodzące przy powierzchni cięcia.

EN

In this paper an influence of oxygen, HTPAC plasma, laser and water cutting on 10 mm thickness plates from S 700MC and S 690QL steel surface quality was described. Quality assessment was measured by surface quality (square deviation, coarseness, angle chamfer), width of cutting gap, perforation method, structural and hardness changes in the area near the cutting surface.

20

Semi-industrial simulation of hot rolling and controlled cooling of Mn-Al TRIP steel sheets

Grajcar A., Skrzypczyk P., Woźniak D., Kołodziej S.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 57, nr 1

38--47

EN

Purpose: The aim of the work is a semi-industrial physical simulation of thermomechanical rolling and controlled cooling of advanced high-strength steels with increased Mn and Al content. Design/methodology/approach: Four steels of various Mn and Nb concentration were thermomechanically rolled in 3 and 5 passes using a modern LPS line for physical simulation of hot rolling at a semi-industrial scale. The hot deformation course is fully automated as well as controlled cooling applied directly after finishing rolling. Temperature-time and force-energetic parameters of hot rolling were continuously registered and assessed. Findings: The applied line consisting of two-high reversing mill, roller tables with heating panels, cooling devices and controlling-recording systems reflects industrial hot strip rolling parameters sufficiently. Reduction values and temperature-time regimes are similar to those used in industrial practice whereas strain rate is limited to about 10 s-1 what requires taking into account during comparison. All the steels investigated have high total pressure forces due to the high total content of alloying elements. The critical factor making it possible to obtain high-quality sheet samples with a thickness up to 3.3 mm is applying isothermal heating panels which decrease a cooling rate of thin sheets. Research limitations/implications: The real complete simulation of hot strip rolling requires extension of a used line with a further module for simulation of continuous finishing rolling stages. The work is in progress. Practical implications: The results can be successfully utilized in industrial hot rolling and controlled cooling practices after necessary modifications. Originality/value: The efficient semi-industrial physical simulation of hot strip thermomechanical rolling of some new model AHSS grades containing increased Mn and Al content as well as Nb microadditions was presented.