Degree Of Cold Deformation Research Articles

Influence of the Degree of Cold Drawing on the Microstructure and Properties of Pipes Used for Dampers

Dumpers are the main components of the suspension system with vertical oscillations role in the absorption of the automobile. The combination of suspension coil with dumper is forming the main body of the suspension system. Shock absorber pipe is mainly used for production of motorcycles, cars (sedan) car shock absorber, is the size of the relatively high precision seamless pipe products, its manufacturing costs and lower selling prices relatively seamless, with excellent cost performance, got the car and motorcycle manufacturing industry recognition, are gradually replacing the use of seamless pipes in the area. The cold work process of pipes drawing consists of reducing the cross-section of a pipe by pulling the pipe through series of conical dies. The metal pipe drawing technology has been widely used to manufacture fine pipes. The influence of the degree of cold drawing on the mechanical properties of the carbon steel material were studied using the tensile test and hardness test experiments in order to replicate the service condition of the pipes used for automotive dumpers. Microstructure analysis were perfomed using optical analysis on a LEICA 5000DMI microscope up to 1000X magnitude and SEM images with a dual beam QUANTA 200 3D FEI SEM scanning electron microscope. The purpose of the work is to observe the main effects of the degree of reduction at different gradations by analysing the microstructure and mechanical proprieties behavior. The study used the stress-strain relationship of the tensile test experiment to study the effect of the degree of cold-drawing deformation on the yield strength and tensile strength properties of the dumpers used in automotive industry. The toughness of the low carbon steel used for the dumper manufacture reduces as the degree of drawing deformation increases. The ductility of the material also reduces with increasing degree of rawing deformation. The yield strength of the material was observed to reduce with increasing degree of cold-drawing, an indication of reduction in the ductility and the tensile strength of the material reduced with increasing degree of cold-drawn deformation. After high degrees of cold deformation by drawing, the hardness proprieties are increasing highlighted by cold-straining.

Influence of cold deformation on the corrosion behavior of Ni–Fe–Cr alloy 028

Ni–Fe–Cr alloy 028 (a nickel based super alloy also known as UNS N08028) was subjected to different degree of cold deformation by laboratory rolling to investigate the influence of microstructure on corrosion behavior under two simulated environments, (0.5M NaCl and 1M H2SO4). Experimental results showed that texture had influence on the corrosion rate of this alloy. The corrosion rate under both environments significantly decreased with increase in the ND//〈110〉 orientation. Significant differences in the corrosion rate with increased degree of deformation were mainly related to different amount of the CSL (coincident site lattice) Σ3 boundaries in the ND//〈110〉 oriented grains. The present study contributes to discussion on the CSL boundary formation for improved corrosion resistance.

In-vitro long term and electrochemical corrosion resistance of cold deformed nitrogen containing austenitic stainless steels in simulated body fluid

This work was focused on the evaluation of the corrosion behavior of deformed (10% and 20% cold work) and annealed (at 1050°C for 15min followed by water quenching) Ni-free high nitrogen austenitic stainless steels (HNSs) in simulated body fluid at 37°C using weight loss method (long term), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Scanning electron microscopy (SEM) was used to understand the surface morphology of the alloys after polarization test. It has been observed that cold working had a significant influence on the corrosion resistant properties of these alloys. The weight loss and corrosion rates were observed to decrease with increasing degree of cold working and nitrogen content in the alloy. The corrosion resistance of the material is directly related to the resistance of the passive oxide film formed on its surface which was enhanced with cold working and nitrogen content. It was also observed that corrosion current densities were decreased and corrosion potentials were shifted to more positive values. By seeing pit morphology under SEM, shallower and smaller pits were associated with HNSs and cold worked samples, indicating that corrosion resistance increases with increasing nitrogen content and degree of cold deformation. X-ray diffraction profiles of annealed as well as deformed alloys were revealed and there is no evidence for formation of martensite or any other secondary phases.

Microstructure and Properties of Cu-Nb Wire Composites

Abstract Nowadays, there is much activity all over the world in development of Cu-Nb composites for their potential use as conductors in high field magnets. This study was aimed at investigation of microstructure, mechanical and electrical properties of Cu-Nb composite wires. The investigated materials have been processed by vacuum furnace melting and casting, and then hot forging and cold drawing. Initial results of research into Cu-Nb composite material obtained using repeated iterative drawing of niobium wires compacted into copper tube, have been also presented in this article. The ultimate tensile strength versus cold deformation degree has been presented. These changes have been discussed in relation to microstructure evolution. It was assumed that repeated drawing of compacted wires is a promising method for fibrous composite production (more than 823,000 Nb fibres of nanometric diameter) characterized by high mechanical properties and electrical conductivity. Original SPD technique applied for Cu-Nb composite deformation result in initial microstructure refinement and improves effectiveness of wire production process.

Optimization of the technological conditions of producing thin sheets and strips from corrosion-resistant VNS9-Sh steel

The technological conditions of producing thin sheets and strips from corrosion-resistant VNS9-Sh steel are optimized at the stages of casting, deformation, and heat treatment. The effect of the as-cast phase composition of VNS9-Sh steel on the ductility of the metal during cold rolling and on the mechanical properties of the end products in the form of thin sheets and strips is studied. It is shown that, for the required level of the mechanical properties of sheets and strips to be achieved, the magnetization of as-cast steel samples should be J = 3–10 mV on the scale of an IFSS (MKL) device, which corresponds to 1.5–5% martensite in the as-cast steel. It is also shown that the required level of mechanical properties (σu ≥ 1470 MPa, δ ≥ 12%) is achieved after work hardening of 17–35% and that 40–50% deformation martensite and 50–60% cold-worked austenite exist in a ready strip if the magnetization of as-cast steel samples is 3–10 mV and the strip is subjected to work hardening. The effect of tempering temperature in the range 100–450°C is studied to increase the yield strength of the steel in the form of a ready strip at low degrees of cold deformation (17–25%). The increase in the yield strength without a decrease in the ultimate tensile strength is maximal after tempering at 125°C for 1 h due to strain aging processes.

Cold deformation and heat treatment influence on the microstructures and corrosion behavior of AISI 304 stainless steel

In the present study AISI 304 stainless steel with different degrees of cold deformation and annealing parameters were investigated. Microstructural evolutions by optical micrography and scanning electron microscopy showed relatively fully austenitic ultrafine-grained structure obtained after annealing at 700°C for 80 min. The volume fraction of α′-martensite increased with increasing compressive deformation rate and maximum volume fraction of α′-martensite was attained in the samples subjected 0⋅65% strain. The potentiodynamic polarization results in 3% NaCl indicated that the corrosion current density increased with cold deformation, while after annealing, it reduced from 2⋅86 to 2⋅29 μA cm−2, showing an enhancement of corrosion resistance. The immersion test showed that the austenitic ultrafine-grained structure exhibits moderate and more uniform pitting corrosion attack compared to the coarser grain in NaCl solution.Dans cette étude, on a examiné un acier inoxydable AISI 304 ayant différents taux de déformation à froid et différents paramètres de recuit. L’analyse de l’évolution de la microstructure par micrographie optique et par microscopie électronique à balayage a montré une structure à grains ultrafins et presque complètement austénitique obtenue après un recuit à 700°C pendant 80 minutes. La fraction volumique de martensite α′ augmentait avec l’augmentation du taux de déformation en compression et la fraction volumique maximale de martensite α′ était atteinte par les échantillons soumis à une déformation de 0·65%. Les résultats de polarisation potentiocinétique dans 3% de NaCl indiquaient que la densité du courant de corrosion augmentait avec la déformation à froid, alors qu’après le recuit, elle était réduite de 2·86 μA/cm2 à 2·29 μA/cm2, montrant ainsi une augmentation de la résistance à la corrosion. L’épreuve d’immersion dans la solution de NaCl a montré que la structure austénitique à grains ultrafins exhibait une attaque par corrosion localisée modérée et plus uniforme comparée au grain plus grossier.

Defect-induced Au precipitation in Fe–Au and Fe–Au–B–N alloys studied by in situ small-angle neutron scattering

Nanoscale Au precipitation in high-purity Fe–Au and Fe–Au–B–N alloys has been studied by in situ small-angle neutron scattering during isothermal aging at 550°C and complementary ex situ transmission electron microscopy. The high temperature precipitation behavior in samples having received different degrees of cold deformation has been studied to explore the potential self-healing of deformation-induced defects by Au precipitation. It is found that dislocations induced by prior plastic deformation strongly facilitate the formation of Au precipitates, as no significant precipitation is observed for undeformed samples. Defect-induced Au precipitates are formed both at dislocations and along grain boundaries where the defect density is high. The fact that the Au atoms only precipitate on deformation-induced defects demonstrates that solute gold atoms act as efficient self-healing agents in the ferrous matrix. The addition of B and N is found to retard the Au precipitation.

Effect of Tempering Temperature on Microstructure and Properties of Cold Deformed Low Carbon Bainitic Steel

In order to research the cold deformation work hardening characteristic of new type low carbon bainitic steel, this article studies the effect of different degrees of cold deformation (elongation and compression) and different tempering temperatures on microstructure and mechanical properties of 15SiMn2Mo low carbon beinaitic steel. The results showed that with the tempering temperature increasing after 10% pre-tension deformation, the tensile strength and yield strength of the test material increased first and then decreased, and reached its peak value at 300°C, roughly the same as the strength of hot-rolling and 300°C tempering. With the compression deformation degree rising, the hardness of test material increased and showed the test material has good work hardening performance. Streamline and "z" shape ferrite banding appeared in microstructure. With the tempering temperature increasing, the microstructure of compressed deformation steel recoveried and recrystallized, the tendency of ferrite along the streamline was weakened, the new refining granular phase was enhanced and uniformity of microstructure was improved. The microstructure refinement was significantly increased with the compressive deformation degree rising.

Optimization of the structure and properties of high-strength microalloyed steel rolled product in relation to degree of cold deformation

The effect of small degrees of reduction on the properties of high-strength microalloyed steel cold-rolled product are studied. Features are established for rolled product structure and property formation in relation to chemical composition and production parameters. Production recommendations are developed providing the highest set of rolled product properties for the steels in question. Production processes developed on the basis of established features are approved under industrial manufacturing conditions.

Combined thermal desorption spectroscopy, differential scanning calorimetry, scanning electron microscopy and X-ray diffraction study of hydrogen trapping in cold deformed TRIP steel

Thermal desorption spectroscopy (TDS) is a very important tool when evaluating hydrogen–material interactions. It allows a distinction to be drawn between different hydrogen traps in the material based on determination of the peak temperatures for hydrogen desorption during heating. These temperatures depend on the metallurgical and microstructural characteristics of the material and provide important information on the possible mechanisms of hydrogen embrittlement. In the present work TDS experiments were performed on a transformation-induced plasticity (TRIP) steel and combined with an in-depth characterization of the microstructure by scanning electron microscopy, X-ray diffraction and differential scanning calorimetry. The TRIP steel was subjected to different degrees of cold deformation in order to correlate the changing microstructure with the TDS peaks. In order to improve our understanding the results obtained for the TRIP grade steel were also compared with those obtained for electrolytically pure iron, which contained only a limited amount of possible trap sites. Here as well, an increasing number of defects were introduced by cold deformation. Significant differences between the two materials and a significant impact of the degree of cold deformation were observed for TRIP steels, allowing a correlation between the TDS peaks and specific microstructural features.

Study of the Hydrogen Traps in a High Strength TRIP Steel by Thermal Desorption Spectroscopy

Thermal desorption spectroscopy (TDS) is a very important tool in hydrogen related research. It allows to distinguish between the different types of microstructural hydrogen traps based on the analysis of the different temperatures at which hydrogen desorbs from the material during heating. These peak temperatures depend on the metallurgical and microstructural characteristics of the steel under investigation and provide important information on the possible mechanisms for hydrogen embrittlement (HE). In the present work, multiple TDS experiments and an in-depth study of the microstructure were performed on a TRIP steel (TRIP700) that was previously cold deformed in order to make a correlation between the microstructural features of this material, e.g. grain boundaries, dislocations, martensite formation and the peaks that became visible during TDS. The results obtained for the TRIP grade were compared with those obtained for electrolytic pure iron, which only contained a limited amount of possible trap sites such as grain boundaries and an increasing amount of dislocations due to previous application of cold deformation. Significant differences between both materials and a significant impact of the degree of cold deformation for TRIP steels were observed.

New Ti-Alloy with Negative and Zero Thermal Expansion Coefficients

Most materials expand upon heating due to the anharmonicity of the atomic potential energy. This thermal expansion is one of the intrinsic properties of any material which is very difficult to be controlled. Recently, a negative thermal expansion factor was introduced to those Ti-alloys with high elastic softening when cold deformed. This negative thermal expansion factor is changeable in these types of alloys depending on the alloy composition, degree of cold deformation, and thermal history of the alloy. This change gives a lot of room to control the coefficient of thermal expansion (CTE) of those Ti-alloys to turn from positive though zero to negative values and vice versa. In this paper, the appearance of the NTE factor is discussed and the possible methods to control the final thermal expansion coefficient to achieve a zero thermal expansion coefficient are presented. The unique thermal expansion behavior of the alloys will locate them as an excellent candidate in sensing apparatus and other precious equipments.

Effect of cold plastic deformation on the structure of granular pearlite in carbon steels

Carbon steel with a structure of granular pearlite has been investigated by methods of scanning electron microscopy and transmission electron microscopy as a function of the degree of cold deformation. It has been shown that with increasing degree of deformation the microstructure of the ferritic constituent changes regularly from dislocation to cellular and to microbanded. It has been established that the structural state of the granular pearlite is stable upon deformation to 50%. An increase in the carbon concentration in the ferrite occurs. Fragmentation of carbide particles into blocks and their subsequent dissolution hawe been observed upon deformation exceeding 50%. Fine-dispersed globular carbides are formed in the ferrite matrix.

Specific features of the formation of the microstructure of titanium nickelide upon thermomechanical treatment including cold plastic deformation to degrees from moderate to severe

X-ray diffraction, electron microscopy, microhardness measurements, and differential scanning calorimetry have been used to investigate the formation of the dislocation substructure and nanocrystalline and amorphous structures in Ti-Ni shape-memory alloys depending on the degree of cold deformation by rolling and post-deformation annealing. The moderate deformation (e = 0.25) leads to the formation of a developed dislocation substructure; with an increase in the deformation to e = 2, the dislocation substructure is gradually substituted by a mixed nanocrystalline and amorphous structures. The residual martensite completely disappears as the deformation increases in the interval of e = 2−3 or upon annealing in the interval of 200–300°C. Annealing at 400°C after a moderate deformation leads to the formation of a polygonized (“nanosubgrain”) dislocation substructure in austenite. As the initial deformation increases to e = 2, this structure is gradually substituted by a nanocrystalline structure of austenite. Annealing after deformation to intermediate degrees (e = 0.75−1.0) results in the formation of a mixture of nanocrystalline and submicrocrystalline polygonized structures.

The impact of cold deformation, annealing temperatures and chemical assays on the mechanical properties of platinum

In order to form the necessary data base on platinum and platinum metals, certain tests were carried out on platinum samples of different purity of 99.5%, 99.9% and 99.99%. The degree of cold deformation, annealing temperature and chemical assays were tested as well as their impact on the mechanical properties of platinum. The Vickers hardness (HV) values were determined with different deformation degree, starting from annealing temperatures for platinum of different purity and tensile strength (Rm), flow limit (Rp0,2) and elongation (A) in the function of annealing temperatures and annealing time at a constant deformation degree.

On the Significance of Nature of Strain-Induced Martensite on Phase-Reversion-Induced Nanograined/Ultrafine-Grained Austenitic Stainless Steel

We recently described the reversal of strain-induced martensite to the parent austenite phase in the attempt to produce nanograins/ultrafine grains via controlled annealing of heavily cold-worked metastable austenite. The phase-reversion-induced microstructure consisted of nanocrystalline (d < 100 nm), ultrafine (d ≈ 100 to 500 nm), and submicron (d ≈ 500 to 1000 nm) grains and was characterized by high strength (800 to 1000 MPa)–high ductility (30 to 40 pct) combination, which was a function of cold deformation and temperature-time annealing sequence.[1] In this article, we demonstrate that the success of the approach in obtaining nanograined/ultrafine-grained (NG/UFG) structure depends on the predominance of dislocation-cell–type structure in the severely deformed martensite. Electron microscopy and selected area electron diffraction analysis indicated that with an increase in the degree of cold deformation there is transformation of lath martensite to dislocation-cell–type martensite, which is a necessary prerequisite to obtain phase-reversion-induced NG/UFG austenite. The transformation of lath-type to dislocation-cell–type martensite involves refinement of packet and lath size and break up of lath structure. Based on detailed and systematic electron microscopy study of cold-deformed metastable austenite (~45 to 80 pct deformation) and constant temperature-time annealing sequence, when the phase reversion kinetics is rapid, our hypothesis is that the maximization of dislocation-cell–type structure in lieu of lath-type facilitates NG/UFG structure with a high strength–high ductility combination. Interestingly, the yield strength follows the Hall–Petch relation in the NG/UFG regime for the investigated austenitic stainless steel.

Effect of cold deformation on the properties and structure of corrosion-resistant alloy KhN30MDB

The effect of the degree of cold deformation on the structure and mechanical and corrosive properties of the corrosion-resistant alloy KhN30MDB have been studied in detail. Deformation regimes that provide for a high level of strength properties and satisfactory plasticity, combined with high corrosion resistance, including general and pitting corrosion and sulfide corrosion cracking in hydrogen sulfide, have been determined.

Modelling the correlation between processing parameters and properties of maraging steels using artificial neural network

An artificial neural network (ANN) model is developed for the analysis and simulation of the correlation between the properties of maraging steels and composition, processing and working conditions. The input parameters of the model consist of alloy composition, processing parameters (including cold deformation degree, ageing temperature, and ageing time), and working temperature. The outputs of the ANN model include property parameters namely: ultimate tensile strength, yield strength, elongation, reduction in area, hardness, notched tensile strength, Charpy impact energy, fracture toughness, and martensitic transformation start temperature. Good performance of the ANN model is achieved. The model can be used to calculate properties of maraging steels as functions of alloy composition, processing parameters, and working condition. The combined influence of Co and Mo on the properties of maraging steels is simulated using the model. The results are in agreement with experimental data. Explanation of the calculated results from the metallurgical point of view is attempted. The model can be used as a guide for further alloy development.

Influence of hard cold working on microstructure and properties of annealing copper tubes

This work gives results of influence of temperature and deformation degree on changes in the metal grain growth of drawn copper tubes, because this mutual dependence was observed. Copper tubes samples, chemical content of 99,97 % Cu and 0,024 % P, were exposed to recrystallized annealing after drawing. The annealing was carried out at temperatures of 573, 623, 673, 723, 773, 823 and 873 K, for 60 minutes, in laboratory conditions. Investigation results show that after drawing with high cold deformation degree (96 - 99 %), the annealing leads to the changes in the continuous grain growth with increased temperature. The smaller grain size appears at 823 K in comparison with the lower annealing temperature. Annealing has influence on mechanical characteristics of tested samples and during drawing of copper tubes these characteristics are adequately changed: with regard to the annealing at the 773 K, the characteristics of strength and plasticity increase as a result of decreased grain size. The increase of annealing temperature to 873 K leads to the increased grain size and decreased values of strength and plasticity characteristics.

Electrochemical and corrosion behaviour of cold rolled AISI 301 in 1 M H 2SO 4

Stainless steels (SS) are widely used in several fields. In recent years, the good corrosion resistance as well as the remarkable mechanical properties of SS have made it an even more utilised material. Such extensive utilisation produces new concern about its ability to maintain good properties after many working processes. In this paper an AISI 301 SS with different degrees of cold deformation has been considered. The cold working of these materials produces some important changes in the microstructure (i.e. grain size, crystallographic texture) and involves phase transformations (γ→α′). Electrochemical measurements have been used to investigate the corrosion behaviour of the alloy in sulphuric acid in the presence of chlorides. In the anodic behaviour of the cold rolled with respect to the annealed SS, a moderate variation of the passivity region but a remarkable increase of the current density was observed. Morphological analyses have been performed to relate the electrochemical results to the alloy structure. The relationship between metallurgical properties and corrosion behaviour has been discussed.