Optimisation of the Deoxidation Degree and Modification on the Cast Steel Properties Improvement at Low Temperature

2013 ◽  
Vol 58 (3) ◽  
pp. 763-767
Author(s):  
Z. Sierant
Keyword(s):  
Low Temperature ◽  
Liquid Metal ◽  
Impact Strength ◽  
Directional Solidification ◽  
Cast Steel ◽  
Steel Grade ◽  
Gating System ◽  
The Impact ◽  
Steel Properties ◽  
Selection Of

Abstract Industrial conditions of obtaining thick-walled and shaped castings intended for operations at temperatures: minus 40÷60°C are presented in the paper. The selection of a cast steel grade is based on known studies [1,10,14], however due to castings wall thickness (70-240mm), the way of preparing liquid metal (deep deoxidation and modification, argon stirring in a ladle) and conditions of filling mould cavities (gating system assuring quiet filling, directional solidification and avoiding a formation of inessential heat centres), were developed to assure the required impact strength. Maintaining these parameters as well as the selection of heat treatments for the produced massive castings allowed to achieve the impact strength over 50 J/cm2 at minus 40°. This value was obtained for walls of various thickness

scholarly journals Impact Strength of Austenitic and Ferritic-Austenitic Cr-Ni Stainless Cast Steel in -40 and +20°C Temperature

2014 ◽  
Vol 59 (3) ◽  
pp. 1103-1106
Author(s):  
B. Kalandyk ◽  
R. Zapała ◽  
Ł. Boroń ◽  
M. Solecka
Keyword(s):  
Impact Strength ◽  
Volume Fraction ◽  
Cast Steel ◽  
Testing Machine ◽  
Charpy Impact ◽  
Impact Testing ◽  
Two Phase ◽  
Steel Grades ◽  
Charpy Impact Testing ◽  
The Impact

Abstract Studies described in this paper relate to common grades of cast corrosion resistant Cr-Ni steel with different matrix. The test materials were subjected to heat treatment, which consisted in the solution annealing at 1060°C followed by cooling in water. The conducted investigations, besides the microstructural characteristics of selected cast steel grades, included the evaluation of hardness, toughness (at a temperature of -40 and +20oC) and type of fracture obtained after breaking the specimens on a Charpy impact testing machine. Based on the results of the measured volume fraction of ferrite, it has been found that the content of this phase in cast austenitic steel is 1.9%, while in the two-phase ferritic-austenitic grades it ranges from 50 to 58%. It has been demonstrated that within the scope of conducted studies, the cast steel of an austenitic structure is characterised by higher impact strength than the two-phase ferritic-austenitic (F-A) grade. The changing appearance of the fractures of the specimens reflected the impact strength values obtained in the tested materials. Fractures of the cast austenitic Cr-Ni steel obtained in these studies were of a ductile character, while fractures of the cast ferritic-austenitic grade were mostly of a mixed character with the predominance of brittle phase and well visible cleavage planes.

Improvement of Impact Strength of Polyglycolic Acid for Self-Degradable Tools for Low-Temperature Wells

2015 ◽  
Author(s):  
Masayuki Okura ◽  
Shinya Takahashi ◽  
Takuma Kobayashi ◽  
Hikaru Saijo ◽  
Takeo Takahashi
Keyword(s):  
Low Temperature ◽  
Impact Strength ◽  
Recovery Process ◽  
Polyglycolic Acid ◽  
Suitable Material ◽  
Well Completion ◽  
Morphological Studies ◽  
Completion Process ◽  
The Cost ◽  
The Impact

Abstract Recent increases in the stage count of hydraulic fracturing has increased the time and cost for well completion. Simplifying time-consuming processes is crucial for economic success. The use of degradable materials for components of downhole tools has several advantages, such as eliminating or simplifying the recovery process of the tools. Polyglycolic acid (PGA), a hydrolyzable polymer, is a suitable material for these components. PGA has already been used in frac balls because of its high mechanical strength and appropriate degradation characteristics. However, in low-temperature wells close to the glass transition temperature of PGA, there are problems with tool breakage during installation or stimulation because of the changes in the mechanical properties of PGA at low temperatures. This paper focuses on the improvement of the impact strength of PGA. A study of modifiers identified the additives that are highly compatible with PGA. Morphological studies of mixtures showed finely dispersed additive domains within a PGA matrix. The impact strength of the mixture was twice as high as that of neat PGA. A formulation was identified that optimized the impact strength while retaining degradability, processability, and machinability similar to that of neat PGA. The improvement of the impact strength broadens the range of applications that PGA tooling is suitable for and helps to reduce the cost and time of the well completion process.

Raising the impact strength of cast steel by modification with yttrium

1976 ◽  
Vol 10 (5) ◽  
pp. 586-587
Author(s):  
I. P. Volchok ◽  
A. V. Tsarev ◽  
V. P. Rudenko
Keyword(s):  
Impact Strength ◽  
Cast Steel ◽  
The Impact

scholarly journals The Impact of the Melting and Pouring Process on the Quality of the Biggest Rocking Bell Called Vox Patris

2019 ◽  
Vol 1 (1) ◽  
pp. 230-237
Author(s):  
Dariusz Bartocha ◽  
Czesław Baron
Keyword(s):  
Liquid Metal ◽  
Computer Simulations ◽  
Final Stage ◽  
Gating System ◽  
System Parameters ◽  
University Of Technology ◽  
Filling System ◽  
Alloy Properties ◽  
The Impact

Abstract The paper describes the process of melting, metalworking and pouring the form of the world's largest 55-ton rocking bell called Vox Patris. The project was carried out by Pracownia Ludwisarska of Jan Felczyński from Przemyśl in cooperation with Rduch Bells & Clocks from Czernica and Metalodlew SA from Kraków. Comprehensive scientific and technical support of the project was provided by the Department of Foundry of the Silesian University of Technology. The bell is made of bronze, which is an alloy of copper and tin with a content of tin at the level of 20%. The foundry, where the melting and pouring process took place, had two 14 ton electric furnaces, 15 ton transport pouring ladle and a 60 ton collection ladle. Therefore, it was necessary to determine the minimum temperature of the pouring and the conditions for holding the liquid metal so that the metal from the first cast would not solidify before accumulating its total amount (four melts) (Bartocha and Baron, 2015; Bartocha and Baron, 2016). The study presents the tests of alloy properties and a series of computer simulations. Thanks to them the maximum and minimum permissible temperature of metal overheating has been determined (Bartocha, 2017). The final stage of the cast was the mold pouring process. The filling system was responsible for the correct performance of this process. This system comprised a tank (collector) under a doublestopper 60-ton main ladle, an eleven-meter tapping spout, an infusion tank and a downgate. The task of the gating system is uniform and continuous supply of liquid metal to the mold until it is completely filled. The unusual layout, that was used, required checking many factors. Various configurations of the system parameters have been tested based on the series of computer simulations (Czochlarski and Bukowski, 1935; Ignaszak, 1999).

scholarly journals Wide – Ranging Influence of Mischmetal on Properties of GP240GH Cast Steel

2012 ◽  
Vol 12 (4) ◽  
pp. 85-94
Author(s):  
J. Kasińska ◽  
M. Gajewski
Keyword(s):  
Rare Earth ◽  
Impact Strength ◽  
Cast Steel ◽  
Rare Earth Metals ◽  
Plastic Properties ◽  
Metallic Inclusions ◽  
Inclusion Morphology ◽  
Three Point Bend Test ◽  
Point Bend ◽  
The Impact

Abstract This paper presents influence of rare earth metals (REM) on the properties of GP240GH cast carbon steel. The research has been performed on successive industrial melts. Each time ca 2000 kg of liquid metal was modified. The rare earth metals were put into the ladle during tapping of heat melt from the furnace. Because of this the amount of sulphur in the cast steel was decreased and the non-metallic inclusion morphology was significantly changed. It was found that non metallic inclusions the cracking mechanism of Charpy specimens and the impact strength were all changed. The following properties were tested: mechanical properties (σy, σUTS), plastic properties (necking, elongation) and impact strength (SCI). In the three-point bend test the KJC stress intensity factor was evaluated.

Methods for Restricting Maximum Exposure Rate in Computerized Adaptative Testing

Methodology ◽  
2007 ◽  
Vol 3 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Juan Ramon Barrada ◽  
Julio Olea ◽  
Vicente Ponsoda
Keyword(s):  
Measurement Accuracy ◽  
Computerized Adaptive Testing ◽  
Computation Time ◽  
Adaptive Testing ◽  
Exposure Rate ◽  
Control Parameters ◽  
The Impact ◽  
Two Alternatives ◽  
Selection Of ◽  
Maximum Exposure

Abstract. The Sympson-Hetter (1985) method provides a means of controlling maximum exposure rate of items in Computerized Adaptive Testing. Through a series of simulations, control parameters are set that mark the probability of administration of an item on being selected. This method presents two main problems: it requires a long computation time for calculating the parameters and the maximum exposure rate is slightly above the fixed limit. Van der Linden (2003) presented two alternatives which appear to solve both of the problems. The impact of these methods in the measurement accuracy has not been tested yet. We show how these methods over-restrict the exposure of some highly discriminating items and, thus, the accuracy is decreased. It also shown that, when the desired maximum exposure rate is near the minimum possible value, these methods offer an empirical maximum exposure rate clearly above the goal. A new method, based on the initial estimation of the probability of administration and the probability of selection of the items with the restricted method ( Revuelta & Ponsoda, 1998 ), is presented in this paper. It can be used with the Sympson-Hetter method and with the two van der Linden's methods. This option, when used with Sympson-Hetter, speeds the convergence of the control parameters without decreasing the accuracy.

Расчетные методы оценки ударной вязкости сварных элементов с трещинами

2020 ◽  
Vol 44 (3) ◽  
pp. 22-36
Author(s):  
Keyword(s):  
Stress Intensity ◽  
Impact Strength ◽  
Welded Joints ◽  
Development Process ◽  
Welded Joint ◽  
Operating Temperature ◽  
Crack Development ◽  
Heterogeneous Structure ◽  
Critical Crack Length ◽  
The Impact

Практика показывает, что для сварных конструкций, эксплуатируемых в условиях Крайнего Севера необходимо уделять внимание работоспособности сварных соединений при низких температурах. Металл сварных соединений в процессе воздействия обработки изменяет свои свойства, снижается ударная вязкость, образуется гетерогенная структура с большой степенью разнозернистости. Чтобы оценивать и иметь возможность правильно контролировать термическое воздействие и последствия сварочного процесса, требуется решить задачу аналитического определения ударной вязкости для всех зон сварного соединения. В настоящей статье представлен инженерный метод оценки ударной вязкости, применимый для любой зоны сварного соединения, в которой имеется острый или особый концентратор напряжений – трещина. Разработанный аналитический метод расчета ударной вязкости отражает качественную и количественную картину взаимосвязи структурно-механических характеристик и работы развития трещины в диапазоне температур 77…300 К. Предложенная схематизация зависимости критического коэффициента интенсивности напряжений от температуры позволила найти коэффициенты, характеризующие свойства материала, и выполнить расчеты изменения предела текучести и предела прочности от температуры эксплуатации. Построены графики зависимости работы развития трещины от температуры эксплуатации для сталей 15ГС и 17ГС, сравнение которых с экспериментальными данными показывает удовлетворительное согласование. Найдено, что при напряжениях предела выносливости отношение работы развития трещины к критической длине трещины постоянно, не зависит от температуры и для сталей 15ГС и 17ГС равно около 10. Ключевые слова: ударная вязкость, работа разрушения, коэффициент интенсивности напряжений, трещина, феррито-перлитная сталь, зона термического влияния. For welded structures under operation in the Far North, attention must be paid to the performance of welded joints at low temperatures. The properties of metal of welded joints are changed in the process of treatment, its toughness decreases, and a heterogeneous structure with a large range of different grain sizes is formed. In order to evaluate and be able to correctly control the thermal effect and the consequences of the welding process, it is necessary to solve the problem of analytical determination of impact strength for all zones of the welded joint. The paper presents an engineering method for evaluation of the impact strength applicable to any area of the welded joint in which there is a sharp or super sharp stress concentrator – a crack. The developed analytical method for calculating the impact strength reflects a qualitative and quantitative codependency of structural and mechanical characteristics and the process of crack development in the temperature range of 77–300 K. The proposed schematization of dependence of the critical coefficient of stress intensity on the temperature made it possible to find coefficients characterizing the properties of the material and to perform calculations of changes in yield strength and tensile strength on operating temperature. Graphs of the crack development process dependency on the operating temperature for 15ГС and 17ГС steels were constructed, and their comparison with experimental data displays satisfactory agreement. It was found that at endurance limit stresses, the ratio of the crack development process to the critical crack length is constant, non-dependent on temperature, and is equal to 10 for 15ГС and 17ГС steels. Keywords: impact strength, fracture work, stress intensity factor, crack, ferrite-pearlite steel, heat affected zone, steel tempering.

Impact Strength, Flexural Modulus and Wear Rate of PMMA Composites Reinforced by Eggshell Powders

2020 ◽  
Vol 38 (7A) ◽  
pp. 960-966
Author(s):  
Aseel M. Abdullah ◽  
Hussein Jaber ◽  
Hanaa A. Al-Kaisy
Keyword(s):  
Impact Strength ◽  
Wear Rate ◽  
Flexural Modulus ◽  
Matrix Material ◽  
Weight Fraction ◽  
Pure Pmma ◽  
Calcination Process ◽  
The Matrix ◽  
The Impact ◽  
Interface Bond

In the present study, the impact strength, flexural modulus, and wear rate of poly methyl methacrylate (PMMA) with eggshell powder (ESP) composites have been investigated. The PMMA used as a matrix material reinforced with ESP at two different states (including untreated eggshell powder (UTESP) and treated eggshell powder (TESP)). Both UTESP and TESP were mixed with PMMA at different weight fractions ranged from (1-5) wt.%. The results revealed that the mechanical properties of the PMMA/ESP composites were enhanced steadily with increasing eggshell contents. The samples with 5 wt.% of UTESP and TESP additions give the maximum values of impact strength, about twice the value of the pure PMMA sample. The calcination process of eggshells powders gives better properties of the PMMA samples compared with the UTESP at the same weight fraction due to improvements in the interface bond between the matrix and particles. The wear characteristics of the PMMA composites decrease by about 57% with increases the weight fraction of TESP up to 5 wt.%. The flexural modulus values are slightly enhanced by increasing of the ESP contents in the PMMA composites.

BOFORS 2RM2

Alloy Digest ◽  
1965 ◽  
Vol 14 (5) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Low Temperature ◽  
Mechanical Strength ◽  
Physical Properties ◽  
Tensile Properties ◽  
Cast Steel ◽  
Heat Treating ◽  
High Mechanical Strength ◽  
Temperature Performance

Abstract BOFORS 2RM2 is a hardenable stainless cast steel having good weldability, high mechanical strength and improved corrosion resistance. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on low temperature performance and corrosion resistance as well as casting, forming, heat treating, machining, and joining. Filing Code: SS-169. Producer or source: Aktiebolaget Bofors.

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