INFLUENCE OF AUTOFRETTAGE ON RESIDUAL STRESS INTENSITY FACTORS OF INTERNALLY OR EXTERNALLY CRACKED GUN BARRELS
Wissam Moustafa AI-Hozwany;
Abstract
A traditional method of improving structural strength against cracking is through the existence of residual stresses. In the case of gun barrels, the beneficial residual stresses can be obtained by using the autofrettage process. This technique is carried out by applying an internal pressure sufficient to plastify a portion of the wall leaving the outer part elastic. Then this applied pressure is released leaving behind appreciable residual stresses. The estimation of these residual stresses reqmres an accurate knowledge of mechanical properties of gun barrels materials. In addition, the cyclic pressurization of gun barrels ( firing and untiring) tends to produce radial cracks at the bore. The presence of residual stresses in the cracked gun barrels can significantly influence their fatigue and fracture behavior. In order to predict the fatigue growth rates of such cracks, and hence the safe-life , a knowledge of the residual stress intensity factor, Km, is very essential.
The first part of the present work is concerned with the chemical composition, heat treatment and microstructure of three types of high strength steels which are called gun steel. Also, impact toughness, tensile properties and reverse yielding in small plastic strain range are evaluated. In addition, fracture toughness and fatigue crack growth rates were estimated experimentally using compact tension specimens.
Charpy V-notch impact toughness is determined at the temperature range
-70 °C to +70 °C . Tensile testing results showed that the monotonic plastic tensile behavior is almost linear. Tensile loading up to different values of plastic pre-strain (up to 2.5%) followed by reverse loading in the compression mode are determined and described by relevant equations for future modeling of the autofrettage process of gun barrels. The experiments illustrated that the elastic unloading range is much less than twice the initial yield strength of the material, which indicates a high degree of Bauschinger effect. Also, it is
The first part of the present work is concerned with the chemical composition, heat treatment and microstructure of three types of high strength steels which are called gun steel. Also, impact toughness, tensile properties and reverse yielding in small plastic strain range are evaluated. In addition, fracture toughness and fatigue crack growth rates were estimated experimentally using compact tension specimens.
Charpy V-notch impact toughness is determined at the temperature range
-70 °C to +70 °C . Tensile testing results showed that the monotonic plastic tensile behavior is almost linear. Tensile loading up to different values of plastic pre-strain (up to 2.5%) followed by reverse loading in the compression mode are determined and described by relevant equations for future modeling of the autofrettage process of gun barrels. The experiments illustrated that the elastic unloading range is much less than twice the initial yield strength of the material, which indicates a high degree of Bauschinger effect. Also, it is
Other data
| Title | INFLUENCE OF AUTOFRETTAGE ON RESIDUAL STRESS INTENSITY FACTORS OF INTERNALLY OR EXTERNALLY CRACKED GUN BARRELS | Other Titles | تأثير الإجهادات المتبقية الناتجة عن عملية الفري – اللدن على معاملات شدة الإجهاد في مواسير المدافع المشروخة من الداخل أو الخارج | Authors | Wissam Moustafa AI-Hozwany | Issue Date | 1999 |
Attached Files
| File | Size | Format | |
|---|---|---|---|
| B11446.pdf | 957.27 kB | Adobe PDF | View/Open |
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