Rupture Strength Research Articles

Classification of surface roughness for CNC face milling of Inconel 625 superalloy utilizing cutting force signal features with SVM and ANN

Superalloys, commonly referred to as high-performance alloys, possess remarkable characteristics that enable them to operate effectively at temperatures significantly surpassing their melting points. These alloys exhibit exceptional strength properties (i.e., corrosion resistance, high tensile strength, creep resistance, rupture strength, and the ability to retain their strength even at elevated temperatures). These inherent properties of superalloys introduce intricate challenges during the machining or cutting process, resulting in unforeseen and abrupt modifications to the interaction between the workpiece and the cutting tool. The fluctuations in interactions can give rise to inconsistencies in the surface finish of the work material. This research focuses on the characterization/classification of variations in surface roughness during face milling of INCONEL 625 using cutting force signals. Additionally, the study investigates the influence of machining parameters on cutting forces and surface roughness. The research considers five levels for each cutting parameter, including feed rate, cutting speed, and depth of cut. Interaction plots are generated to analyze the relationship between machining parameters and responses, namely surface roughness and cutting forces. In order to classify the surface roughness, a proposed methodology is employed, aiming to identify different classes such as refined, good, and satisfactory surface finishes during milling. Both time domain and frequency domain characteristics of the cutting force data collected during milling are utilized to determine surface quality. Bayesian optimized Support Vector Machine (SVM) and Artificial Neural Network (ANN) models are employed, and a comparison is conducted between them. The SVM model achieved an accuracy of 99.61%, while the ANN model slightly outperformed with an accuracy of 99.74%.

Endurance Strength and Residual Life Assessment of T23 Steel after 96000 Hours of High Temperature and High Pressure Service

The macroscopic morphology, oxide layer characteristics, rupture strength and residual life of T23 steel after 96000 hours of service at high temperature and high pressure were analyzed. The results show that T23 steel pipe has good macroscopic appearance, without obvious abnormal features such as cracks, folds, rolling breaks, double skin, scabs, delaminations and sharp scratches. The chemical composition of different pipe sections conforms to the standard, and the structure is mainly bainite, with uniform distribution and no obvious coarse phase. There is an obvious interface between the metal substrate and the internal oxide layer, and there is an obvious wavy line at the interface. The oxide layer is relatively dense and continuous. The tensile properties at room temperature and high temperature are good. At room temperature, the yield strength exceeds 420MPa, the tensile strength exceeds 540MPa, and the elongation exceeds 19%. After 96000 hours of use, the remaining creep life of T23 split platen superheater submitted for inspection is 84000 hours, and the remaining creep life of T23 rear platen superheater submitted for inspection is 40000 hours.

Influence of the base metal grain size and heat input on decarburization in single pass SAW and multi pass SMAW welded joints of dissimilar ferritic steels

This paper aims to assess a separate influence of heat input and base metal grain size on microstructural evolution in the weld adjacent zone of bainitic steels with 1.5…2.0% Cr, welded or overlayed with consumables with 9% Cr after post-weld heat treatment.Analysis of the width of decarburised layer on microphotographs of welded or overlayed specimens after tempering at 750C. Specimens were made by using different welding approaches: single-pass welding, multi-pass welding and overlaying.It is shown that with an increase of the heat input energy, the width of the resulting decarbonised layer decreases linearly; the increase of the base metal grain size leads to a decrease in the layer width after tempering at 750C. The microhardness testing showed the average hardness in the decarburised layer of 15Kh2M2FBS steel was 161 HV0.1 (minimum – 154 HV0.1), while the average hardness in the rest of the heat-affected zone was 192 HV0.1.Future research may include comparing the creep rupture strength of the weldments made with different welding parameters or base metal grain size to assess the influence of these factors on creep rupture strength.Results permit to achieve minimisation of the rate of carbon diffusion in the weld-adjacent area of the heat-affected zone by means of variation of welded parameters and base metal grain size.An influence of high-diffusivity paths (grain boundaries) on carbon diffusion in the heat-affected zone of dissimilar weldments was confirmed experimentally; the correlation between base metal grain size/welding parameters and the rate of the diffusion during high-temperature exposure was found.

Effect of WC particle size on the microstructure and mechanical properties of Ni–Co coarse grain cemented carbide

AbstractThe effect of different WC grain size additions on the microstructure and grain distribution of Ni–Co coarse crystalline cemented carbide was studied. And then the effect of grain distribution on the mechanical properties of cemented carbide was discussed. The effect of WC grain size on the grain size and coherency of cemented carbide was analyzed by microstructure. And the distribution of grains in the microstructure was investigated by the truncation method. The addition of fine (1.1–1.4 μm), medium (2.3–2.7 μm), and coarse WC (5.6–6.0 μm) particles can increase the nucleation rate of WC grains in the bonded phase. And the higher grain growth driving force can produce the theoretical limitation of nucleation and inhibit the coarsening of WC grains to a certain extent. The WC grain size has an insignificant effect on the frequency of the occurrence of super‐coarse grains in coarse crystalline cemented carbide. The average grain size and super coarse grains in microstructure gradually decrease, which promotes the improvement of transverse rupture strength. The increase of the adjacent degree and the decrease of the mean free path reduce which is beneficial to the improvement of the corrosion resistance of the alloy. The best overall performance of the alloy is achieved when fine‐grained WC is added.

Growing bio-tiles using microbially induced calcium carbonate precipitation

Using the biomimetic process known as microbially induced calcium carbonate precipitation (MICP), the growth of bio-tiles was investigated as an alternative to conventionally fired ceramic tiles which require operating temperatures above 1000 °C, therefore adding to global carbon emissions. The ureolytic activity of Sporosarcina pasteurii was controlled by centrifuging and dilution with fresh yeast extract media. The bio-tiles were grown using a novel submersion method in which custom moulds were placed in exact positions within the bio-reactor and each was mixed individually from beneath. Five parameters were optimised to achieve bio-tiles (dimensions of 100 × 100 × 10 mm) of breaking strength comparable to conventional tiles of equivalent thickness. By optimising ureolytic activity (4.0 mmol/L·min), the cementation solution concentration (0.3 M), the particle size distribution (D10 = 312 μm; D50 = 469 μm), the volume of cementation solution, as well as the addition of supplemental magnesium (0.3 M), bio-tiles with a breaking strength 637 N ± 60 N and a modulus of rupture of 13.0 N/mm2 ± 2.3 N were produced. These parameters exceed the conventional standards of breaking strength and modulus of rupture of 600 N and 8 N/mm2, respectively, the standards set for tiles with a water absorption above 10 %. This is also the first time that an optimum CaCO3 precipitation rate constant has been identified (0.11–0.18 day−1) for producing bio-tiles that meet the strength properties of conventional extruded ceramic tiles. The tile manufacturing technique described in this study is easy to operate and scale since multiple bio-tiles can be produced in larger cementation tanks. This natural tile making process also benefits the environment by operating at room temperature.

A reliable and replicable test protocol for the mechanical evaluation of synthetic meshes

Despite the worldwide spread of surgical meshes in abdominal and inguinal surgery repair, the lack of specific standards for mechanical characterization of synthetic meshes, used in hernia repair and urogynecologic surgery, makes performance comparison between prostheses undoubtedly difficult. This consequently leads to the absence of acknowledged specifications about the mechanical requirements that synthetic meshes should achieve in order to avoid patient discomfort or hernia recurrences.The aim of this study is to provide a rigorous test protocol for the mechanical comparison between surgical meshes having the same intended use. The test protocol is composed of three quasi-static test methods: (1) ball burst test, (2) uniaxial tensile test, and (3) suture retention test. For each test, post-processing procedures are proposed to compute relevant mechanical parameters from the raw data. Some of the computed parameters, indeed, could be more suitable for comparison with physiological conditions (e.g., membrane strain and anisotropy), while others (e.g., uniaxial tension at rupture and suture retention strength) are reported as they provide useful mechanical information and could be convenient for comparisons between devices. The proposed test protocol was applied on 14 polypropylene meshes, 3 composite meshes, and 6 urogynecologic devices to verify its universal applicability towards meshes of different types and produced by various manufacturers, and its repeatability in terms of coefficient of variation.The test protocol resulted easily applicable to all the tested surgical meshes with intra-subject variability characterized by coefficient of variations settled around 0.05. Its use within other laboratories could allow the determination of the inter-subject variability assessing its repeatability among users of alternative universal testing machines.

The role of strength distributions for premature creep failure

Premature and unexpected creep damage is a significant concern in high-temperature engineering. Identifying outliers in creep rupture data is essential for assessing the risk of premature creep failure. This study proposes a new method to evaluate premature creep failure using log-logistic distribution fit of prediction errors and outlier positions. Fitting results for seven different alloys were obtained from extrapolation procedures using soft-constrained machine learning algorithms (SCMLAs) and constrained time-temperature parameters (TTPs) based on prior research. A comprehensive statistical analysis was conducted for all materials. The log-logistic distribution was validated as a suitable method for fitting prediction error distributions. Regression plots demonstrate effective residual balance and accurate outlier capture. The best fitting methods were identified based on the width of the distributions. Outlier positions were used to evaluate the probability of premature creep failure quantitatively. For example, a 0.5% probability of observing creep rupture strengths that are approximately 50% lower than the standardized creep stress was found for TP316H, T321H, and high Cr steels SUH616B. These findings offer valuable insights for estimating premature creep failure in materials.

Effect of Prior Boriding on Microstructure and Mechanical Properties of Nanobainitic X37CrMoV5-1 Hot-Work Tool Steel.

The influence of prior pack boriding on the microstructure and properties of nanobainitised X37CrMoV5-1 hot-work tool steel was investigated in the present work. Pack boriding was conducted at 950 °C for 4 h. Nanobainitising consisted of two-step isothermal quenching at 320 °C for 1 h, followed by annealing at 260 °C for 18 h. A combination of boriding with nanobainitising constituted a new hybrid treatment. The obtained material exhibited a hard borided layer (up to 1822 ± 226 HV0.05) and a strong (rupture strength 1233 ± 41 MPa) nanobainitic core. However, the presence of a borided layer decreased mechanical properties under tensile and impact load conditions (total elongation decreased by 95% and impact toughness by 92%). Compared with borided and conventionally quenched and tempered steel, the hybrid-treated material retained higher plasticity (total elongation higher by 80%) and higher impact toughness (higher by 21%). It was found that the boriding led to the redistribution of carbon and silicon atoms between the borided layer and substrate, which could influence bainitic transformation in the transition zone. Furthermore, the thermal cycle in the boriding process also influenced the phase transformations during subsequent nanobainitising.

Investigation of microstructure, mechanical, and tribological properties of SiC/h-BN/Gr hybrid reinforced Al6061 matrix composites produced by hot extrusion method

In this study, new generation hybrid composite materials were produced by adding SiC, h-BN and Graphite (Gr) to the Al6061 alloy, which has light, corrosion resistant, good formability and weldability properties, giving it abrasion resistance and high strength properties. Five different reinforced and non-reinforced samples were produced, namely Al6061, Al6061%10SiC, Al6061%8SiC%2 h-BN, Al6061%8SiC%2Gr, and Al6061%8SiC%1 h-BN%1Gr, by the hot extrusion method. The density, hardness, microstructure, tensile strength, transverse rupture strength (TRS), and abrasion properties of the synthesized samples are reported in this study. While small agglomerations were observed in the composite materials (10%SiC) produced with a single reinforcement element, it was almost absent in the hybrid composite materials. The hardness of the SiC- and h-BN-containing composites were higher than those of Al6061. The tensile strength and TRS improved relative to those of the reinforcement elements. The addition of h-BN and Gr improved the wear properties.

Selecting a dependence for the approximation of experimental data on secondary creep and creep rupture strength

As a rule, for the evaluation of the mechanical characteristics of a metallic material by secondary creep and creep rupture strength, tests are carried out for uniaxial tension of cylindrical specimens under the influence of a stationary axial force. These mechanical characteristics include the experimental dependence of constant strain rate on nominal stress and the experimental dependence of rupture time on nominal stress. In order not to conduct a large number of experiments, so that these mechanical characteristics can be determined at any nominal stress, one of the two empirical dependencies is used, allowing the corresponding experimental dependences to be approximated with the smallest total error. As such empirical dependences, a power dependence with two material parameters and a fractional power dependence with four material parameters are considered, two of which acquire the definite physical meaning of starting creep stress (the maximum stress at which the strain rate is zero) and break creep stress (the minimum stress at which instantaneous rupture occurs). When choosing an empirical dependence, the author used experimental data obtained by him from mechanical tests for uniaxial tension of cylindrical VT5 and VT6 titanium alloy specimens at 650 °C. The calculated total errors testify that both empirical dependences satisfactorily approximate the considered experimental data.

The Assessment of the Transversal Rupture Strength (TRS) and Hardness of WC-Co Specimens Made via Additive Manufacturing and Sinter-HIP

This study is focused on the mechanical properties of WC-Co composites obtained via Selective Laser Sintering (SLS) using PA12 as a binder. The as-printed samples were thermally debonded and sintered, first in a vacuum, and then sinter-HIP (Hot Isostatic Pressure) at 1400 °C, using 50 bar Ar, which has led to relative densities up to 66%. Optical metallographic images show a microstructure consisting of WC, with an average grain size in the range of 1.4–2.0 µm, with isolated large grains, in a well-distributed Co matrix. The shrinkage of the samples was 43%, with no significant shape distortion. The printing direction of the samples significantly impacts the transversal rupture strength (TRS). Nevertheless, the mechanical strength was low, with a maximum of 612 MPa. SEM images of the fracture surface of TRS samples show the presence of defects that constitute the cause of the low measured values. The hardness values position the obtained composites in the medium coarse classical cemented carbides range. The results were also related to the amount of free Co after sintering, close to the initial one, as assessed by magnetic measurements, indicating a low degree of interaction with PA12 decomposition products.

Fatigue fracture failure analysis of 12Cr12Mo steam turbine blade

Turbine blade is one of the key components in thermal power plant, and its premature failure is a common accident. The fourth blade of the low-pressure turbine unit in a power plant broke, resulting in the unplanned shutdown of the turbine unit. Through different analysis methods, the failure cause of the steam turbine blade was determined. The macro morphology of the fracture was observed by optical light microscope (OLM), and the micro characteristics of the fracture were observed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The mechanical properties of the failed blade were analyzed by room temperature tensile test and Charpy impact test. The results indicated that the root cause of blade fracture was the decrease of fatigue strength and rupture strength caused by high δ-ferrite content. Consistency between crack propagation direction and banded δ-ferrite direction further promotes crack initiation and prolongation. Eventually leading to fatigue fracture of the blade. According to the test and analysis results, some recommendations to prevent the early failure of steam turbine blades are put forward.

Mechanical and GWP assessment of concrete using Blast Furnace Slag, Silica Fume and recycled aggregate

Demolition waste and cement production is responsible for 36 % of total waste produced on earth and 8 % of the worlds CO2 emissions, respectively. Due to limited research on concrete mixes containing ternary cementitious mixes (Ground Granulated Blast-furnace Slag (GGBS) and Silica Fume (SF)) and demolition waste, the paper reviewed the mechanical properties of concrete, and structural performance of reinforced beams. Thereafter, life cycle analysis (LCA) was investigated to understand the true environmental impact, focusing on Global Warming Potential (GWP). Results show that recycled concrete aggregates (RCA) had no significant negative impact on the compressive strength, tensile strength, and modulus of rupture of concrete. The inclusion of GGBS and SF in mixes containing RCA eliminated any negative impact and for all mixes produced greater strengths in comparison to the control mix, due to the secondary reaction of Ca (OH)2 and pore refinement. The flexural behaviour of the concrete beams with 0 %, 25 %, 50 % and 100 % RCA, 25 % GGBS and 5 % SF is similar. LCA results showed that replacing NA with 25 %, 50 % or 100 % RCA has no significant impact on the GWP emissions. This is because of the similar emissions associated with manufacturing and processing of recycled and natural aggregates. However, replacing cement with 5 % SF and 25 % GGBS improves the GWP environmental response of concrete significantly. Additionally, natural aggregates have a higher GWP contribution than that of recycled concrete aggregates by almost 80 % since the process of NA required quarry operation and transportation while the RCA are produced on site from an existing building waste.

Laboratory evaluation of the effect of rice husk fiber on soil properties and behaviors

Soil stabilization is usually used to enhance the soil properties and characteristics. Cement or supplementary cementitious materials (SAMs) are used for soil stabilization. Stabilized soil can be used in several civil constructions and structures such as roads bed, roadside stability and slop, and subgrade layers for pavement structures. Also, developing countries use stabilized soil for building houses due to low-cost, energy-efficient, and environment benefits. In this study, compressed earth blocks (CEBs) stabilized with Rice Husk Fiber without the use of cement are utilized to evaluate the effects of Rice Husk Fiber on the soil properties and behaviors. Different percentages of rice husk fiber (0.5, 1.0, 1.5, 2.0, 2.5, and 3.0%) are blended into the moist clay and pit sand mixture. The CEBs were extracted from the soil mixture and dried. CEB cube crushing strength and modulus of rupture were determined in laboratory tests. The effect of rice husk fiber on the fundamental structural properties of CEBs was studied and compared to those that did not contain rice husk fiber. The results show that increasing the amount of rice husk fiber reduced shrinkage, drying time, cube crushing strength, and modulus of rupture by half (50%) as well as load-carrying capacity by 25%. According to existing guidelines, the compressive strength and modulus of rupture of the CEBs presented in this study are sufficient for use in earth buildings.

Bio-Based Tannin-Furanic-Silk Adhesives: Applications in Plywood and Chemical Cross-linking Mechanisms

Wood polyphenolic extracts, commonly called tannins, are excellent candidates for the production of bioplastics due to their abundance in nature, their commercial availability, and their reactivity. In particular, they were tested as wood adhesives with several hardeners, but their low moisture resistance and their rigidity reduced their technological interest. In the present study, we combined regenerated silk (RS) with tannin-furanic formulations to improve their properties. Three-layer plywood glued with these several fully renewable tannin-silk-furanic adhesives were tested for their mechanical properties: the modulus of elasticity, the modulus of rupture, and both dry and wet shear strength were enhanced when 20 wt % of RS was added. Initially, the cross section of the prepared samples was investigated by scanning electron microscopy, indicating a good dispersion of RS within the tannin-furanic matrix. Afterward, thermomechanical analysis of the adhesive highlighted that RS slows down the polymerization rate, decreasing the cross-linking kinetics of polyfurfuryl alcohol. Chemical investigations through ATR-FTIR and 13C-NMR show the formation of covalent bonds between RS and the furanic matrix. In summary, the combination of bioresources from the vegetal and animal kingdom allows the manufacturing of fully bio-based adhesives with enhanced mechanical properties and water resistance. This represents an important breakthrough in the exploitation of polyphenols, opening perspectives for their application in material science.

Flexural behavior of structure of laminated cementitious composites with different types of mesh reinforcements

In this study, 17 plates of cementitious ferrocement composite structure reinforced with two types of fabrics (jute and polypropylene) derived from biaxially oriented jute and polypropylene canvas with three reference unreinforced plates are experimentally investigated. The aim was to increase the flexural load carrying capacity and ductility of unreinforced laminated composite. The matrix was prepared using a ratio of 1:2:0.3 (Portland cement: sand: fly ash) by weight and water-to-cementitious material ratios (w/cm) of 0.4, 0.5, and 0.6. In accordance with ASTM C1609 procedure, the structural behavior of studied laminated composites with a size of 450 × 100 × 25 mm under a four-point load configuration, including first crack, maximum post cracking strength or modulus of rupture (MOR), deflection, toughness, crack pattern, and failure modes, are investigated with the effectiveness of type of fiber and the number of fabric layer reinforcements. The results indicate that types of fiber and number of layers of fiber have a significant effect on enhancement of resistance, strength, and ductility of the cementitious material mortars. The results showed that the first cracking strength generally decreased as the number of fibric layers increased. In comparison to the reference plates, the first cracking strength decreased by 92.8, 83.0, and 34.3% for plates reinforced with polypropylene fiber at 0.4 w/cm, as layer number increased from zero to six, eight, and ten, respectively. The post-flexural strength of the jute fiber-reinforced plates increased as layer number increased relative to the reference plate, whereas this was completely the opposite for polypropylene fiber-reinforced plates. The maximum flexural strength was 10.82 MPa for plates reinforced with jute fabrics whereas polypropylene fibers had a maximum flexural strength of 5.21 MPa. The post flexural strength of plates reinforced with jute fiber increased for w/cm ratio of 0.6 by 2.1, 68.0, and 78.4%, whereas it dropped for plates reinforced with polypropylene fiber by 6.7, 9.0, and 53.6% as layer number increased from zero to six, eight, and ten, respectively. Polypropylene fiber reinforced plates have a wider crack width than jute fiber reinforced plates and the effect of increasing layer number was not clear, but it did generally reduce crack spacing. A comparison of the maximum post-cracking strength against the first cracking strength indicated that jute fiber plates exhibited deflection hardening behavior, while the behavior was completely reversed for plates reinforced with PP fiber, whose curve behavior was softening deflection. The maximum deflection recorded 18.5 mm, and the energy absorption and deflection capabilities of jute fabric reinforced composites have both improved with layer number increased. Conversely, for polypropylene fabric reinforced composites, where the maximum deflection was 21 mm and the deflection and energy absorption capacity decreased as layer number increased. However, laminates made of polypropylene fabrics displayed significantly weaker bonds than jute fabric laminates, resulting in the appearance of horizontal cracks that separated the Polypropylene laminate layers and spread towards both supports emphasized by SEM test. As a result, the indices described in ASTM C1608 specifications cannot be generalized to the behavior of such materials for such a curve because, based on the experimental data, the calculated residual strength ratio exceeded 100% in only three plates. The toughness values in the composites suggest that this eco-friendly, ductile composite has a promising future in the construction industry.

Influence of Ru content on mechanical, corrosion and oxidation behaviors of WC-15Co cemented carbides

In this work, ruthenium (Ru) was used as an additive for improving the microstructure, mechanical, corrosion and oxidation behaviors of WC-15Co alloy. By analysis, Ru could facilitate the formation of cubic carbides free layer (CCFL), refine the WC crystallite size and enhance the anti-corrosion and anti-oxidation abilities of alloy. The highest hardness, fracture toughness as well as transverse rupture strength (TRS) values of alloys could be obtained by adding 3.0 wt% Ru at the same time. However, all of these properties decreased simultaneously when the Ru content exceeded 3.0 wt%. For corrosion and oxidation behaviors, when the Ru content was 5.0 wt%, the anti-corrosion and anti-oxidation abilities of alloy were the strongest. Thus, an appropriate amount of Ru was regarded as an excellent additive for enhancing the properties of cemented carbides. The strengthening mechanism of Ru was attributed to grain refinement, solution strengthening and the formation of dense oxides (Co3O4 and CoWO4).

Small-Caliber Vascular Grafts Engineered from Decellularized Leaves and Cross-Linked Gelatin.

Despite advances in vascular replacement and repair, fabricating small-diameter vascular grafts with low thrombogenicity and appropriate tissue mechanics remains a challenge. A wide range of platforms have been developed to use plant-derived scaffolds for various applications. Unlike animal tissue, plants are primarily composed of cellulose which can offer a promising, nonthrombogenic alternative capable of promoting cell attachment and redirecting blood flow. By taking advantage of the biocompatibility and mechanical properties of cellulose, we developed small-diameter vascular grafts using decellularized leatherleaf viburnum and cross-linked gelatin. Different terrestrial plant leaves (leatherleaf, spinach, and parsley) were decellularized with sodium dodecyl sulfate, egtazic acid and/or Tergitol, followed by a bleach and Triton X-100 clearing solution, and then evaluated for decellularization efficiency, mechanical integrity, and recellularization potential. Hematoxylin and eosin staining and DNA quantification revealed successful removal of cells in all leatherleaf conditions. Methods of 3D graft fabrication were evaluated, and leatherleaf scaffolds maintained suitable tensile and rupture strength properties. 2D scaffolds and 3D grafts were seeded with rat endothelial cells. Cells remained viable for over 14 days with cell densities comparable to other natural and synthetic scaffolds. This study demonstrates the potential of cost effective and readily available decellularized plants to generate small-diameter vascular grafts capable of recellularization and with suitable mechanical properties. Impact statement Due to the prevalence of coronary heart disease in the United States, small-caliber vascular grafts for coronary bypass surgery are in high demand. We evaluate decellularized plant leaves as potential candidates for small-diameter vascular grafts with appropriate mechanical properties and recellularization potential.

Analysis of Worm Deformation Behavior of GH2132 Superalloy

GH2132 superalloy performances excellent properties, such as the good rupture strength and yield strength below 923K, the fine processing plasticity and the good welding properties. The warm working behavior of GH2132 superalloy at 673 K – 773K is investigated by a thermal simulator in this paper. The results show that the worm working effects at the center of specimen is the most significant compared with other positions. The deformation temperature and strain rate is the key parameters significantly affecting the warm working behavior. The increase of the temperature enhances the recovery softening effect, which reduces the stress and the work hardening effect slightly. The deformation heat is significant with the increasing strain rate, which results in the work hardening behavior does not change markedly. This study provides an important reference for the worm forming of GH2132 superalloy.

Effects of the vacuum hot pressing process on the microstructures, strengthening mechanisms, and mechanical properties of Ni-35Cr-12Mo-3Nb alloys

This research fabricates Ni-35Cr-12Mo-3Nb alloys using the vacuum hot pressing process of PM technology. The experiments used various hot pressing temperatures (1050, 1100, 1150, and 1200 °C) and hot pressing pressures (20, 35, and 50 MPa) to determine the optimal process parameters. The experimental results show that the optimal hot pressing parameters for this alloy were 1100 °C at 35 MPa for 1 h. Among them, the sintered density was enhanced to 8.15 ± 0.01 g cm−3, and the hardness, transverse rupture strength (TRS) and flexural modulus reached 78.0 ± 0.1 HRA, 1404.2 ± 36.8 MPa, and 75.4 ± 3.3 GPa, respectively, and the electrical conductivity was 1.92 ± 0.14 × 104 S cm−1. TEM observation proves that the MoNi and Ni3Nb intermetallic compounds do indeed exist in the Ni-35Cr-12Mo-3Nb alloy after 1100 °C hot pressing at 35 MPa for 1 h. MoNi is an orthorhombic system with diffraction along the [3 4‾ 4] crystal axis, and Ni3Nb is the same system, but along the [100] crystal axis. EBSD analysis results also confirm that this alloy has no obvious grain orientation preference.