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Search Results: 1 - 10 of 16215 matches for " surface work hardening. "
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Influência da rugosidade na resistência à corros?o por pite em pe?as torneadas de a?o inoxidável superaustenítico
Gravalos, Márcio Tadeu;Martins, Marcelo;Diniz, Anselmo Eduardo;Mei, Paulo Roberto;
Rem: Revista Escola de Minas , 2010, DOI: 10.1590/S0370-44672010000100013
Abstract: pitting corrosion resistance has been correlated to the morphological conditions of the surface: a smooth surface finishing decreases the potential for pitting. this study aimed at investigating the relationship between pitting corrosion resistance and surface roughness in the machined surfaces of superaustenitic stainless steel astm a744 grade cn3mn. the samples of the casting steel were cylindrically turned sunder different combinations of cutting conditions, producing different surface roughness patterns. the surfaces of the samples, as machined, were characterized by roughness and hardness. after the application of an accelerated immersion corrosion test, these surfaces were examined in a stereoscope and the weight loss by corrosion was also determined. it was revealed that the samples exhibited different corrosion resistance behaviors, according to the machining conditions applied. a correlation between pitting resistance corrosion and machined surface roughness was evident, and also, the weight loss due to the formation of pits. this study has identified that corrosion can be controlled through the selection of appropriate machining parameters.
Superficial tribological transformation of a ferritic stainless steel by dynamic microindentation  [PDF]
H. Boudoukha, S. Djabi
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.511147

Currently, the stainless steel starts to widen its fields of application in an extraordinary way in medicine and surgery, in the domestic utensils (flatware) and in heavy industry (petrochemistry, nuclear industry and transport). This work consists of making an experimental study on a type of ferritic stainless steel having undergone the test of the microindentation at controlled load and knowing the Superficial Tribological Transformations (STT) caused by this test. It is supposed that it is a simulation with the damages caused on the stainless steels which are in the environment (the effect of hail) or in industry (shot-blasting of the turbines). The analysis of the repeated shocks is based on the mechanical characterization (microhardness, microstructures of the impacts) and geometrical to see the evolution of the diameter and depth of the impacts according to the number of shocks (cycles of impact), in order to know the plastic deformation.

Study on the Effect of Production Parameters and Raw Materials Used on the Mechanical Properties of Leaded Brass (CuZn40Pb2) Alloy  [PDF]
Abdulsalam A. Fadhil, Tawakol A. Enab, Magdy Samuel, Berlanty A. Iskander, Sami A. Ajeel
World Journal of Engineering and Technology (WJET) , 2017, DOI: 10.4236/wjet.2017.52028
Abstract: Leaded brass alloys used progressively in many applications such as gas valves production owing to their excellent machinability, corrosion resistance and some other specifications. However, the production processes of these alloys involve some problems appearing in the last activities of production as a result of cumulative defects of previous production processes. Therefore, the current investigation studies the effect of process parameters during casting, hot extrusion and cold drawing production stages of CuZn40Pb2 leaded brass alloy on the mechanical properties. Starting with casting process, two types of charges were used. The first charge consists of 100% recycles while the second contains 30% of pure materials such as Cu, Zn and Pb in addition to the recycles. For each production stage, alloy hardness, micro-hardness, ultimate tensile strength and elongation were examined. The results illustrated that high hardness values are obtained during casting process due to some impurities such as iron and the effect of cooling rate through solidification. The hardness values decrease during extrusion process and then rise again by cold drawing for the charge of 30% pure materials. Micro-hardness values for the fractured tensile test samples appeared higher than others due to work hardening effect. The best mechanical properties as ultimate tensile strength of CuZn40Pb2 alloy products are appeared into cold forming samples with the 30% pure material added.

SHI Deke,LIU Junhai X'ian Jiaotong University,

金属学报 , 1989,
Abstract: Work hardening of Hadfield manganese steel is mainly from twocauses: 1) a large amount of twinning makes perfect dislocal is or shockley dislo-cations to be blocked up at the coherent twin boundaries. 2) deformation leads tostrong unsymmetrical distortion due to a large number of Mn-C pairs or Mn-vaca-ncy carbon-carbon clusters. It has been demonstrated by TEM observation and in-ternal friction tests. As deformation proceeds, slip constantly accommodates twin-hing shear giving rise to stress relaxation. Thus, Hadfield steel possesses both rapidwork hardening and good ductility.
SHI Deke LIU Junhai Xi'an Jiaotong University,Xi'an,China SHI Deke,Associate Professor,
SHI Deke LIU Junhai Xi''''an Jiaotong University
,Xi''''an,China SHI Deke,Associate Professor

金属学报(英文版) , 1990,
Abstract: The work hardening of Hadfield manganese steel arises mainly form two causes;1)a large amount of twinning makes perfect dislocations or Shockley dislocations to be blocked at the coherent twin boundaries.2)the deformation leads to strong unsymmetrical distortion due to the occurrence of a large number gf Mn-C pairs or Mn-vacancy carbon-carbon cluster.It has been demonstrated by TEM observation and internal friction tests.As deformation pro- ceeds,the slip constantly accomodates twinning shear giving rise to stress relaxation.Thus, the Hadfield steel exhibits both rapid work hardening and good ductility.
Influence of impact energy on work hardening ability of austenitic manganese steel and its mechanism
Li Xiaoyun,Wu Wei,Zu Fangqiu
China Foundry , 2012,
Abstract: To further understand the hardening mechanism of austenitic manganese steel under actual working conditions, the work hardening ability was studied and the microstructures of austenitic manganese steel were observed under different impact energies. The work hardening mechanism was also analyzed. The results show that the best strain hardening effect could be received only when the impact energy reaches or exceeds the critical impact energy. The microstructural observations reveal that dislocations, stacking faults and twins increase with raising impact energy of the tested specimens. The hardening mechanism changes at different hardening degrees. It is mainly dislocation and slip hardening below the critical impact energy, but it changes to the twinning hardening mechanism when the impact energy is above the critical impact energy.
A DFT Calculation of Nb and Ta (001) Surface Properties  [PDF]
Amall Ahmed Ramanathan
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.43A060
First principle calculations are performed using the super cell method with pseudopotentials and plane waves based on the Density Functional Theory (DFT) for the surface structural properties at T = 0 K. Thin slabs of 7 - 13 atomic layers of the clean Nb and Ta (001) surfaces are considered and relaxations, surface energies, and work functions of the fully relaxed slabs are presented. Consistent results are obtained with the Generalized Gradient Approximation (GGA) and the Local Density Approximation (LDA) for the exchange-correlation functional and they compare well with experimental and other theoretical works.
Compaction Behavior of Isomalt after Roll Compaction
Julian Quodbach,Johanna Mosig,Peter Kleinebudde
Pharmaceutics , 2012, DOI: 10.3390/pharmaceutics4040494
Abstract: The suitability of the new isomalt grade galenIQ? 801 for dry granulation and following tableting is evaluated in this study. Isomalt alone, as well as a blend of equal parts with dibasic calcium phosphate, is roll compacted and tableted. Particle size distribution and flowability of the granules and friability and disintegration time of the tablets are determined. Tensile strength of tablets is related to the specific compaction force during roll compaction and the tableting force. In all cases, the tensile strength increases with raising tableting forces. The specific compaction force has a different influence. For isomalt alone the tensile strength is highest for tablets made from granules prepared at 2 kN/cm and 6 kN/cm and decreases at higher values, i.e., >10 kN/cm. Tensile strength of the blend tablets is almost one third lower compared to the strongest tablets of pure isomalt. Friability of pure isomalt tablets is above the limit. Disintegration time is longest when the tensile strength is at its maximum and decreases with higher porosity and lower tensile strengths. Isomalt proves to be suitable for tableting after roll compaction. Even though the capacity as a binder might not be as high as of other excipients, it is a further alternative for the formulation scientist.
Caracteriza??o microestrutural dos alumínios comerciais AA1100, AA1050 e AA1070 e do alumínio superpuro AA1199
Oliveira, Janaina da Costa Pereira Torres de;Padilha, Angelo Fernando;
Rem: Revista Escola de Minas , 2009, DOI: 10.1590/S0370-44672009000300017
Abstract: a comparative study was carried out among three commercial purity aluminums with different levels of purity: aa1100 (99.00%), aa1050 (99.50%) and aa1070 (99.70%), produced on an industrial scale by direct chill (dc) process, and super pure aluminum, aa1199 (99.995%) produced in the laboratory. several techniques of microstructural analysis were used: conventional optical microscopy, scanning electron microscopy, optical microscopy with polarized light, measurements of electrical conductivity and vickers hardness. the three commercial purity aluminums showed an increase in work hardening and a decrease in electrical conductivity as the impurity content increased.
TAO Zengyi LUO Jiaming Huazhong University of Science,Technology,Wuhan,China TAO Zengyi,Faculty of Metallic Materials,Deptof Mechanical Engineering No,Huazhong University of Science,Technology,Wuhan,China,
TAO Zengyi LUO Jiaming Huazhong University of Science and Technology
,Wuhan,China TAO Zengyi,Faculty of Metallic Materials,Dept.of Mechanical Engineering No.,Huazhong University of Science and Technology,Wuhan,China

金属学报(英文版) , 1990,
Abstract: The influence of laser surface melting and induction hardening on the surface structure,con- tact fatigue life and failure behaviour of the nodular cast iron has been investigated.The con- tact fatigue life can be improved by both laser treatment and induction hardening,but the fail- ure process and type are different from each other.The former is due to lumpy and deep spal- ling caused by crack propagation between the quenching zone and the substrate,and the latter is due to nubby and surface flaking caused by the oil wedged action into surface cracks.
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