Improvement of Cyclic Strength of Carbon Steel by Various Surface Treatments

2010 ◽  
Author(s):  
Antanas Ciuplys
Keyword(s):  
Fatigue Strength ◽  
Carbon Steel ◽  
Surface Hardening ◽  
Sample Surface ◽  
Cyclic Strength ◽  
Metal Fatigue ◽  
Heating And Cooling ◽  
High Fatigue ◽  
Huge Impact ◽  
The Impact

Fatigue strength is one of the most important mechanical properties. Durability and reliability of car parts are often defined by their fatigue strength, since most of them are loaded with dynamic, repeating or variable loads and the main type of failure is metal fatigue. Various surface hardening methods have a huge impact on fatigue strength of structural materials. The choice of surface processing method is determined by properties and microstructure of a material, as well as the purpose and working conditions of part’s material. Very often the optimum processing is a combination of several methods, which enables to obtain the required properties (high fatigue strength, wear, etc.). The impact of several combined surfaces processing on the fatigue strength of carbon steel samples is investigated in the work. The surface was hardened using different processing combinations: by hardening with high frequency electricity currents, rolling by rollers, heating and cooling under different temperatures. Experimentally it is proved that thermal treatment of plastically deformed carbon steel significantly increases fatigue strength. Experiments showed that after surface hardening with the given regimes, the microstructure and residual stresses are formed in such way that fatigue crack begins to grow under the hardened sample surface.

Peculiarities of Fatigue Fracture of Steel Hardened by Various Surface Treatments

2012 ◽  
Vol 527 ◽  
pp. 107-112
Author(s):  
Antanas Ciuplys ◽  
Valdas Kvedaras
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Carbon Steel ◽  
Fatigue Fracture ◽  
High Frequency ◽  
Surface Hardening ◽  
Fatigue Crack Initiation ◽  
Sample Surface ◽  
Metal Fatigue ◽  
The Impact

Fatigue strength is one of the most important mechanical properties. Durability and reliability of car parts is often defined by their fatigue strength, since most of them are loaded with dynamic, repeating or variable loads and the main type of failure is metal fatigue. Fatigue crack usually starts on the metal surface. The interrelationship of the surface layer together with the characteristics of internal metal volume determine the value of fatigue limit and the coefficient level of stresses’ intensity, which is required for the start of fatigue crack. Various hardening methods of surface have a huge impact on fatigue strength of structural materials. The choice of surface processing method is determined by properties and microstructure of a material, as well as the purpose and working conditions of part’s material. Very often the optimum processing is a combination of several methods, which enables to obtain the required properties (high fatigue strength, wear, etc.). Hardening with high-frequency electric current (HfEC) is widely used process for the surface hardening of steel. The components are heated by means of an alternating magnetic field to a temperature within or above the transformation range followed by immediate quenching. The core of the component remains unaffected by the treatment and its physical properties are those of the bar from which it was machined. Investigation of specific fatigue fracture properties enables to determine the kinetic of processes, related with fatigue crack initiation and propagation. Analysing fractures of machine parts and comparing them with the most specific “mode” fractures it is possible to determine the nature of affecting loads and the reason of part failure. The impact of several combined surfaces processing on the fatigue strength and fractures of carbon steel samples is investigated in the work. The surface was hardened using different processing combinations: by hardening with high frequency electricity currents, rolling by rollers, heating and cooling under different temperatures. Experimentally it was proved that thermal treatment of plastically deformed carbon steel significantly increases fatigue strength. After surface hardening with the given regimes, the microstructure and residual stresses are formed in such way that fatigue crack begins to grow under the hardened sample surface. Samples, in which the fatigue crack initiates inside the sample, have higher fatigue strength than the samples, the fatigue crack of which initiates on the surface.

Impact Bending Fatigue Strength of Gear Teeth Case-Hardened by Nitriding and Carburizing

2000 ◽  
Author(s):  
Koji Maenosono ◽  
Akira Ishibashi ◽  
Keiji Sonoda
Keyword(s):  
Fatigue Strength ◽  
Power Transmission ◽  
Plasma Nitriding ◽  
Impact Fatigue ◽  
Gear Teeth ◽  
High Tension ◽  
High Fatigue ◽  
Alloy Steels ◽  
Almost All ◽  
The Impact

Abstract Almost all gears used for power transmission of automobiles have been case-hardened by carburizing. Recently, strict demand for reducing running noise and vibration from the power transmission gears requires, in most cases, an additional finishing operation such as grinding and/or honing after carburizing. Nitriding is conducted at a temperature of about 820 K which is lower than the transformation temperature, and thus quenching is not required, resulting in smaller heat treatment deterioration. However, nitrided gears hardly used in practice as for power transmission gears. In the present investigation, experiments were conducted, using test gears case-hardened by two different methods, carburizing and plasma-nitriding. Test results showed that the fatigue strength of carburized gears was higher than that of nitrided gears in most cases when the test gears were made from the same steel. However, the impact fatigue strengths of nitrided gears made from a high tension steel with additional alloy elements Mo and V were higher than those of carburized gears made from the carbon and alloy steels which have been, used as for gear material. The other high tension steel containing neither Mo nor V could not bring about a sufficiently high fatigue strength in comparison with the conventional carburized gears. It should be noted that the impact fatigue strength of carburized gears made from the high tension steel was higher than the ones made of conventional carburizing steel.

INFLUENCE THE QUENCHING AND TEMPERING ON THE MICROSTRUCTURE, MECHANICAL PROPERTIES AND SURFACE ROUGHNESS, OF MEDIUM CARBON STEEL

2018 ◽  
Vol 18 (1) ◽  
pp. 125-135
Author(s):  
Sattar H A Alfatlawi
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Surface Roughness ◽  
Carbon Steel ◽  
Cold Water ◽  
Medium Carbon Steel ◽  
Medium Carbon ◽  
Heating And Cooling ◽  
Treatment Processes ◽  
Quenching And Tempering

One of ways to improve properties of materials without changing the product shape toobtain the desired engineering applications is heating and cooling under effect of controlledsequence of heat treatment. The main aim of this study was to investigate the effect ofheating and cooling on the surface roughness, microstructure and some selected propertiessuch as the hardness and impact strength of Medium Carbon Steel which treated at differenttypes of heat treatment processes. Heat treatment achieved in this work was respectively,heating, quenching and tempering. The specimens were heated to 850°C and left for 45minutes inside the furnace as a holding time at that temperature, then quenching process wasperformed in four types of quenching media (still air, cold water (2°C), oil and polymersolution), respectively. Thereafter, the samples were tempered at 200°C, 400°C, and 600°Cwith one hour as a soaking time for each temperature, then were all cooled by still air. Whenthe heat treatment process was completed, the surface roughness, hardness, impact strengthand microstructure tests were performed. The results showed a change and clearimprovement of surface roughness, mechanical properties and microstructure afterquenching was achieved, as well as the change that took place due to the increasingtoughness and ductility by reducing of brittleness of samples.

LUCEFIN GROUP 20NiCrMo2-2(1.6523), 20NiCrMoS2-2 (1.6526)

Alloy Digest ◽  
2020 ◽  
Vol 69 (12) ◽  
Keyword(s):  
Wear Resistance ◽  
Fatigue Strength ◽  
Physical Properties ◽  
Tensile Properties ◽  
Heat Treating ◽  
Medium Size ◽  
Case Hardening ◽  
Low Carbon ◽  
High Fatigue

Abstract Lucefin Group 20NiCrMo2-2 and 20NiCrMoS2-2 are low-carbon, Ni-Cr-Mo, alloy case-hardening steels that are used in the carburized or carbonitrided, and subsequently quench hardened and tempered, condition. These steels are, in general, used for medium-size case-hardened parts requiring high fatigue strength and wear resistance. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on forming, heat treating, and joining. Filing Code: SA-866. Producer or source: Lucefin S.p.A..

SANBAR 20

Alloy Digest ◽  
1999 ◽  
Vol 48 (8) ◽  
Keyword(s):  
Wear Resistance ◽  
Fatigue Strength ◽  
Tensile Properties ◽  
High Strength ◽  
Heat Treating ◽  
Steel Company ◽  
High Fatigue ◽  
Molybdenum Steel ◽  
Rolled Condition

Abstract SANBAR 20 is a high-strength chromium-molybdenum steel with high-fatigue strength and excellent wear resistance in the as-rolled condition. The primary application is use as integral drill rods. This datasheet provides information on composition, hardness, and tensile properties. It also includes information on forming, heat treating, and machining. Filing Code: SA-501. Producer or source: Sandvik Steel Company.

scholarly journals Family reported outcomes, an unmet need in the management of a patient's disease: appraisal of the literature

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
R. Shah ◽  
F. M. Ali ◽  
A. Y. Finlay ◽  
M. S. Salek
Keyword(s):  
Quality Of Life ◽  
Family Members ◽  
Unmet Need ◽  
Reliability And Validity ◽  
Chronic Health Condition ◽  
Family Quality Of Life ◽  
Good Reliability ◽  
Huge Impact ◽  
The Impact

Abstract Background A person’s chronic health condition or disability can have a huge impact on the quality of life (QoL) of the whole family, but this important impact is often ignored. This literature review aims to understand the impact of patients' disease on family members across all medical specialities, and appraise existing generic and disease-specific family quality of life (QoL) measures. Methods The databases Medline, EMBASE, CINHAL, ASSIA, PsycINFO and Scopus were searched for original articles in English measuring the impact of health conditions on patients' family members/partner using a valid instrument. Results Of 114 articles screened, 86 met the inclusion criteria. They explored the impact of a relative's disease on 14,661 family members, mostly 'parents' or 'mothers', using 50 different instruments across 18 specialities including neurology, oncology and dermatology, in 33 countries including the USA, China and Australia. These studies revealed a huge impact of patients' illness on family members. An appraisal of family QoL instruments identified 48 instruments, 42 disease/speciality specific and six generic measures. Five of the six generics are aimed at carers of children, people with disability or restricted to chronic disease. The only generic instrument that measures the impact of any condition on family members across all specialities is the Family Reported Outcome Measure (FROM-16). Although most instruments demonstrated good reliability and validity, only 11 reported responsiveness and only one reported the minimal clinically important difference. Conclusions Family members' QoL is greatly impacted by a relative's condition. To support family members, there is a need for a generic tool that offers flexibility and brevity for use in clinical settings across all areas of medicine. FROM-16 could be the tool of choice, provided its robustness is demonstrated with further validation of its psychometric properties.

scholarly journals Time Granularity Impact on Propagation of Disruptions in a System-of-Systems Simulation of Infrastructure and Business Networks

2021 ◽  
Vol 18 (8) ◽  
pp. 3922
Author(s):  
Mateusz Iwo Dubaniowski ◽  
Hans Rudolf Heinimann
Keyword(s):  
Recovery Time ◽  
System Of Systems ◽  
Future Research ◽  
Business Networks ◽  
Simulation Experiments ◽  
Huge Impact ◽  
High Level ◽  
Systems Simulation ◽  
Different Characteristics ◽  
The Impact

A system-of-systems (SoS) approach is often used for simulating disruptions to business and infrastructure system networks allowing for integration of several models into one simulation. However, the integration is frequently challenging as each system is designed individually with different characteristics, such as time granularity. Understanding the impact of time granularity on propagation of disruptions between businesses and infrastructure systems and finding the appropriate granularity for the SoS simulation remain as major challenges. To tackle these, we explore how time granularity, recovery time, and disruption size affect the propagation of disruptions between constituent systems of an SoS simulation. To address this issue, we developed a high level architecture (HLA) simulation of three networks and performed a series of simulation experiments. Our results revealed that time granularity and especially recovery time have huge impact on propagation of disruptions. Consequently, we developed a model for selecting an appropriate time granularity for an SoS simulation based on expected recovery time. Our simulation experiments show that time granularity should be less than 1.13 of expected recovery time. We identified some areas for future research centered around extending the experimental factors space.

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