scholarly journals Evaluation of the Properties of an Electro-Sinter-Forged Bearing Steel

2020 ◽  
Author(s):  
Róbert Bidulský ◽  
Federico Simone Gobber ◽  
Alessandro Fais ◽  
Jana Bidulská ◽  
Marco Actis Grande
Keyword(s):  
Rupture Strength ◽  
Bearing Steel ◽  
The Other ◽  
Mechanical Resistance ◽  
Metallic Materials ◽  
Experimental Characterization ◽  
Transverse Rupture Strength ◽  
Sinter Forging ◽  
Bearing Steels ◽  
Conventional Press

In this study one of the most innovative sintering techniques up to date was evaluated: Electro-Sinter-Forging (ESF). Despite it has been proved to be effective in densifying several different metallic materials and composites, bearing steels such as 100Cr6 have never been processed so far. Pre-alloyed Astaloy CrM powders have been ad-mixed with either graphite or graphene and then processed by ESF to produce a 100Cr6 equivalent composition. Porosity has been evaluated by optical microscopy and compared to that one of 100Cr6 commercial samples. Mechanical properties such as hardness and transverse rupture strength were tested on samples produced by employing different process parameters and then submitted to different treatments (machining, heat treatment). The experimental characterization highlighted that porosity is the factor mostly affecting mechanical resistance of the samples, correlating linearly to the transverse rupture strength. Hardness on the other side does not correlate to the mechanical resistance because process related cracking has a higher effect on the final properties. Promising results were obtained that give room to the sinterability by ESF of materials difficult to sinter by conventional press and sinter techniques.

scholarly journals Innovative Densification Process of a Fe-Cr-C Powder Metallurgy Steel

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 665
Author(s):  
Federico Simone Gobber ◽  
Jana Bidulská ◽  
Alessandro Fais ◽  
Róbert Bidulský ◽  
Marco Actis Grande
Keyword(s):  
Heat Treatment ◽  
Powder Metallurgy ◽  
Process Parameters ◽  
Rupture Strength ◽  
Mechanical Resistance ◽  
Metallic Materials ◽  
Transverse Rupture Strength ◽  
Sinter Forging ◽  
Metallurgy Steel ◽  
Main Factor

In this study, the efficacy of an innovative ultra-fast sintering technique called electro-sinter-forging (ESF) was evaluated in the densification of Fe-Cr-C steel. Although ESF proved to be effective in densifying several different metallic materials and composites, it has not yet been applied to powder metallurgy Fe-Cr-C steels. Pre-alloyed Astaloy CrM powders have been ad-mixed with either graphite or graphene and then processed by ESF. By properly tuning the process parameters, final densities higher than 99% were obtained. Mechanical properties such as hardness and transverse rupture strength (TRS) were tested on samples produced by employing different process parameters and then submitted to different post-treatments (machining, heat treatment). A final transverse rupture strength up to 1340 ± 147 MPa was achieved after heat treatment, corresponding to a hardness of 852 ± 41 HV. The experimental characterization highlighted that porosity is the main factor affecting the samples’ mechanical resistance, correlating linearly with the transverse rupture strength. Conversely, it is not possible to establish a similar interdependency between hardness and mechanical resistance, since porosity has a higher effect on the final properties.

Effect of Nano-Carbides on the Microstructure and Mechanical Properties of Ti(C,N)-Based Cermets

2011 ◽  
Vol 105-107 ◽  
pp. 2071-2075
Author(s):  
Yan Lei ◽  
Jing Fu Liu ◽  
Bing Yang
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Formation Mechanism ◽  
Ostwald Ripening ◽  
Rupture Strength ◽  
The Other ◽  
Homogeneous Microstructure ◽  
Heterogeneous Microstructure ◽  
Transverse Rupture Strength ◽  
Black Core

In this paper, Ti(C,N)-Based cermets with addition of nano-carbides were fabricated by conventional powder metallurgy techniques. Then the mechanical properties, microstructure and corresponding formation mechanism have been investigated. According to the results, the microstructures of sintered cermets are composed of three kinds of hard grains: one with black core/grey shell, one with white core , and the other with no core. In addition, with more nano-carbides adding, the number of white core grains increases and that of black core grains decreases. It is also found that sintered cermets with nano-carbide additions exhibit higher transverse rupture strength and higher hardness than the others originated from much finer and more homogeneous microstructure. However, cermets with nano-micro carbide additions show the most poor mechanical properties among all sintered cermets, including conventional cermets, due to the obviously heterogeneous microstructure. And this can be explained by Ostwald ripening theory.

Effect of TaC on W-Ti-Co Ultrafine Cemented Carbides

2011 ◽  
Vol 306-307 ◽  
pp. 598-602 ◽  
Author(s):  
Chong Cai Zhang ◽  
Qun Qun Yuan ◽  
Quan Wang ◽  
Zhi Yong Sheng ◽  
Long Wang
Keyword(s):  
Rupture Strength ◽  
Average Particle Size ◽  
High Energy ◽  
The Other ◽  
Cemented Carbides ◽  
Average Particle ◽  
Transverse Rupture Strength ◽  
Comprehensive Performance ◽  
Energy Ball ◽  
Different Content

The W-Ti-Co powders was doped different content of TaC with an average particle size of 270nm were prepared by 72 hours high-energy ball milling. The powder was cold isostatic pressed and vacuum sintered at 1380°C. The physical properties and the micrographs of samples were detected. The main conclusions were as follow: the density and Cobalt magnetic decreased with the content of TaC increasing, the coercivity increased at first and then decreased, the coercivity of alloy with 0.6wt.% TaC was higher than the other. When the content of TaC was less than 0.6wt.%, the hardness increased with the content of TaC increasing .While when the content of TaC was more than 0.6wt.%, the hardness decreased obviously. Comparing with the alloy without TaC doped, the transverse rupture strength (TRS) of the alloy with 0.4wt.%TaC increased to a larger extent. When the content of TaC was more than 0.4wt.%, the transverse rupture strength (TRS) decreased with the content of TaC increasing. The TaC could inhibit the grain growth, and the comprehensive performance of the alloy with 0.4wt.% TaC was best.

scholarly journals Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 476 ◽  
Author(s):  
Chao Gu ◽  
Min Wang ◽  
Yanping Bao ◽  
Fuming Wang ◽  
Junhe Lian
Keyword(s):  
Fatigue Life ◽  
Quantitative Analysis ◽  
Critical Size ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Property ◽  
Bearing Steel ◽  
Fatigue Properties ◽  
Bearing Steels ◽  
Inclusion Distribution

The fatigue property is significantly affected by the inner inclusions in steel. Due to the inhomogeneity of inclusion distribution in the micro-scale, it is not straightforward to quantify the effect of inclusions on fatigue behavior. Various investigations have been performed to correlate the inclusion characteristics, such as inclusion fraction, size, and composition, with fatigue life. However, these studies are generally based on vast types of steels and even for a similar steel grade, the alloy concept and microstructure information can still be of non-negligible difference. For a quantitative analysis of the fatigue life improvement with respect to the inclusion engineering, a systematic and carefully designed study is still needed to explore the engineering dimensions of inclusions. Therefore, in this study, three types of bearing steels with inclusions of the same types, but different sizes and amounts, were produced with 50 kg hot state experiments. The following forging and heat treatment procedures were kept consistent to ensure that the only controlled variable is inclusion. The fatigue properties were compared and the inclusions that triggered the fatigue cracks were analyzed to deduce the critical sizes of inclusions in terms of fatigue failure. The results show that the critical sizes of different inclusion types vary in bearing steels. The critical size of the spinel is 8.5 μm and the critical size of the calcium aluminate is 13.5 μm under the fatigue stress of 1200 MPa. In addition, with the increase of the cleanliness of bearing steels, the improvement of fatigue properties will reach saturation. Under this condition, further increasing of the cleanliness of the bearing steel will not contribute to the improvement of fatigue property for the investigated alloy and process design.

scholarly journals Effect of Boride Layer on PM HSS AISI M2 on the Mechanisms Acting in the Transverse Rupture Strength Test

2017 ◽  
Vol 21 (1) ◽  
Author(s):  
Mateus Leal Arcego ◽  
Júlio César Giubilei Milan ◽  
César Edil da Costa ◽  
Elisangela Aparecida dos Santos de Almeida
Keyword(s):  
Rupture Strength ◽  
Boride Layer ◽  
Strength Test ◽  
Transverse Rupture Strength

scholarly journals Complex Precipitates of TiN-MCx in GCr15 Bearing Steel

2019 ◽  
Author(s):  
Qianren Tian ◽  
Guocheng Wang ◽  
Xinghu Yuan ◽  
Qi Wang ◽  
Seetharaman Sridhar
Keyword(s):  
Volume Fraction ◽  
Early Stage ◽  
Nucleation Site ◽  
Bearing Steel ◽  
Precipitation Behavior ◽  
Heterogeneous Nucleation Site ◽  
Bearing Steels ◽  
Advancing Front ◽  
Gcr15 Bearing Steel ◽  
Second Phases

Nitride and carbide are the second phases which play an important role in the performance of bearing steel, and their precipitation behavior is complicated. In this study, TiN-MCx precipitations in GCr15 bearing steels were obtained by non-aqueous electrolysis, and their precipitation mechanisms were studied. TiN is the effective heterogeneous nucleation site for Fe7C3 and Fe3C, therefore, MCx can precipitate on the surface of TiN easily, its chemistry component consists of M3C and M7C3 (M = Fe, Cr, Mn) and Cr3C2. TiN-MCx with high TiN volume fraction, TiN forms in early stage of solidification, and MCx precipitates on TiN surface after TiN engulfed by the solidification advancing front. TiN-MCx with low TiN volume fraction, TiN and MCx form in late stage of solidification, TiN can not grow sufficiently and is covered by a large number of precipitated MCx particles.

scholarly journals Tail-Actuator Propulsion Device for Aquatic Robot

2006 ◽  
Vol 18 (1) ◽  
pp. 89-96 ◽  
Author(s):  
Andrea Manuello Bertetto ◽  
◽  
Maurizio Ruggiu
Keyword(s):  
Mathematical Model ◽  
Numerical Procedure ◽  
Numerical Data ◽  
Operating Principle ◽  
The Other ◽  
Kinematics And Dynamics ◽  
Experimental Characterization ◽  
Fish Propulsion ◽  
Geometrical Dimensions ◽  
Simplified Mathematical Model

In this paper an aquatic device inspired to the fish propulsion is proposed. At the first, the operating principle of the fluidic actuator and its experimental characterization are presented. Then, the results of numerous tests carried out on the integrated tail-actuator device are shown either in terms of thrust exerted or as biomorphism of its kinematics. The tests were run at several driven frequencies with different fins depending on their geometrical dimensions and compliances. On the other hand, a simplified mathematical model of the propulsion system, based on the calculation of the instantaneous tail kinematics and dynamics by means of a numerical procedure, is proposed with the aim of simulating performances either in terms of thrust exerted or kinematics behavior. Finally a discussion about the results obtained and a comparison between experimental and numerical data are presented.

Sign in / Sign up

Export Citation Format

Share Document