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العنوان
Some mechanical and physical properties of welded steel joints /
المؤلف
Estafonos, Amany Nagy Kamel.
هيئة الاعداد
باحث / أماني ناجي كامل اسطفانوس
مشرف / طارق أحمد فؤاد خليفه
مناقش / محمود أحمد شافعي
مناقش / طارق أحمد فؤاد خليفه
الموضوع
Welded steel.
تاريخ النشر
2004.
عدد الصفحات
180 p. :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
الهندسة الميكانيكية
تاريخ الإجازة
1/1/2004
مكان الإجازة
جامعة بنها - كلية الهندسة بشبرا - Mechanics
الفهرس
Only 14 pages are availabe for public view

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from 186

Abstract

The aim of the present work is to evaluate the physical, microstructure and mechanical properties of weld deposit metal of 316L stainless steels and stainless steels welded joints.
The ferrite numbe for the weld deposit metal specimens was measured in three orthogonal surface directions F,B &Talso the opposite transverse section of specimens were measured Tn.It was found that the average of the measurements has the highest value at the top surface (F), while the lowest average of measured value is recorded in the bottom (B).However the both transverse sides surface do not have the same average.
It was found that ferrite number (FN) population means is varied by_+ 0.14533 FN compared with the arithmetic mean at 95 % confidence level. Some of these specimens were aged at low temperatures 400ْ C for various holding time, ranging from 100 to 5000 hours.The effect of aging on FN and structure was investigated and compared with as-weld condition. The ferrite numbers were measured as a function of agind time to evaluate the ferrite stability.Measurements were taken on each specimen before and after aging (500 hr the FN = 15.091,2000
hr the FN=13.55 and at 5000 hr the FN=13.098)
The measured of ferrite phase using mange gauge showed diffeent values after aging compared with the values which were evaluated using optical metallography. The mange gauge measure value of ferrite after 500 hr aging is about 6% reduction from the as weld value. While for 5000 hr aging is about 17.5% redution from the as weld value. The microstructure of the weld metal which shows a significant reduction on the ferrite phase (black phase), When observing the microstructure chang of feerrite content by optical metallorgraphy, it can be noted that the ferrite phase content was reduced to 30% after aging for 500 hr, while the ferrite phase content reduction reached to 60 % adter aging for 5000 hr.
This contradiction between the appearance of ferrite phase the microstructure at the measured ferrite content is transformed into other phases which have the same magnetic i.e. magnetic phase.
Charpy V-notch impact tests were performed for eadh of the as-weld metal, and deposits material before and after aging at low temp. 400ْ C. The tests were carried out at - 197, - 150, -100, -50, 25 RT (room temperature) 100, 150 and 300ْ C. The impact energy transition curves show less impact values in both upper and lower shelves after aging . The transitions cuves of the aged are shifted to the right side with respect to the as weld oneVickers micro-hardness was carried out for the weld joint : at the base metal, heat affected and weld metal zones. It was measured in as-weld condition and after aging for 100, 200, 500, 1000, 2000, 3000, 4000, and 5000 hr at low temperature aging 400ْ C. The maximum variation in the hardness values is through the weld joint zones after aging for 2000 hr . For aging at 5000 hr the hardness variations through each weld zones become less.