Local Heat Treatment of Goat Udders Influences Innate Immune Functions in Mammary Glands

The long time world railways practice has shown that the rail-wheel mechanical system is one of the most unique and complex systems. During transportation a variety of rail and wheel damages can take place due to service conditions, used material and technology of their production. Damage mechanisms such as wear, surface cracks, spalls, shells and elastic deformation as a result to rolling contact stresses can significantly reduce the service life of railway wheel sets and track and causing a negative impact on the rolling noise as well as on the ridding comfort. This paper presents that a proper understanding of the heating and cooling mechanisms of the wheel surface for the required hardening purpose is necessary and a mathematical model is developed to present hardening process (local heat treatment). As the material of wheel and rail is carbon steel and the heat treatment (hardening) is the most effective and efficient methods for decreasing wear on wheel sets because wheel sets are more prone to wear due to their excessive use as compare to rail or track.. The only local heat treatment is justifiable technically and economically which is applied to the most loaded working surface of wheel sets without dealing with the central part or bulk of the material. The quality of heat treatment of working surfaces of wheels is associated with the use of concentrated energy sources, such as electron and laser beam and plasma jets. This paper presents some experimental results besides the theoretical reasoning and discussions which show that the wear on the wheel sets ridges after plasma hardening is much lower (2.5 to 3 times) than the other standard heat treatments and hence due to the proper contact of railwheel the vehicle system dynamics improves as a result.

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Use of the Aging Effect to Change the Local Properties of Structure Components

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.137.35 ◽

2010 ◽

Vol 137 ◽

pp. 35-79 ◽

Cited By ~ 4

Author(s):

Mehdi Asadi ◽

Nicole Schulze ◽

Heinz Palkowski

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Aging Treatment ◽

Heat Treating ◽

Local Heat ◽

Local Deformation ◽

Strengthening Effect ◽

Subsequent Aging ◽

Local Heat Treatment ◽

Local Properties

This research deals with processes leading to local strengthening effects in Advanced High Strength Steels (AHSS). Dual phase (DP), retained austenite (RA) - both hot and cold rolled - and complex phase (CP) steels have been investigated to examine the effect of thermal and mechanical processing parameters on local properties. For this purpose, a method has been investigated to achieve local strengthening, namely local deformation and local heat treatment. Samples were locally deformed by bending and embossing processes. A local deformation with defined pre-strains leads to enhanced hardness and strengthening. A subsequent aging treatment leads to a further increase in mechanical properties. Local heat treatment was applied using a laser and an electron beam. Following local heat treatment with selected parameters, the microstructure of the surface and the cross section as well as the mechanical properties were evaluated by light optical, scanning as well as transmission electron microscopy, hardness measurement, tensile testing and thermal modelling. It can be stated that with partial heat treatment, local high strengthening can be produced. At lower heat treating temperatures, this effect could be attributed to bake hardening. With increased heat treating temperature, the initial microstructure near the surface is affected. A model can be improved, which defines the correlation between the influencing parameters and the local properties. The influence of over-aging in locally strengthen regions has been studied. For this investigation, parameters are stable to locally adjust the strengthening effect. Partial strengthening of AHSS by local deformation or local heat treatment can open up new fields of applications for locally using the strengthening effect to only influence relevant areas of interest, thus providing the potential for saving energy and designing the component’s behaviour.

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