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Experimental Study of Steady-State Tube Expansion by using Conical Mandrel
دراسة تجريبية لعملية التوسيع المستقر للأنابيب باستخدام قوالب مخروطية

Authors: Tahseen Taha Othman تحسين طه عثمان --- Hazim Khalil Khalaf حازم خليل خلف --- Jalal Khorshed Alyan جلال خورشيد
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2015 Volume: 33 Issue: 7 Part (A) Engineering Pages: 148-166
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

An Experimental study Conducted for the continuous expansion process of the brass (70/30) tubes by pushing a conical rigid mandrel inside the tube mechanically.This study included an empirical part throughout the test of (60) tube samples to give a different expanding ratios up to (40%) and almost at semi-cone angle of the mandrel ranging from small, medium and large angles (10°,20° and 30°) in addition to that the samples with different relative thicknesses (0.05, 0.1, 0.15 and 0.2).The theoretical part ensures that for the predicted with relative forming stress that needed to complete the expansion process in addition to the changes in the stresses of the various exposed a wall of the sample tube ,The study included the influence of work hardening property which earns this study has a great importance in how to deal with this property. This study showed a good agreement between both theoretical and practical parts, especially in determining the relative forming stress necessary for the success of the operation that showed the relative forming stress increases as the expansion ratio and the semi-cone angle of the mandrel increases has ranged between (0.1-0.7) of the samples tested. Noting that the formation is influenced by the first was much larger than the second was. Whereas the relative forming stress decrease as the relative thickness increase for the same expansion ratio and the semi-cone angle of the mandrel formation.

أجريت دراسة تجريبية لعملية توسيع الأنابيب المستقرة وذلك من خلال دفع قالب تشكيل فولاذي مخروطي الشكل بداخل أنابيب من البراص(70/30) ميكانيكيا. وتضمنت الدراسة جانباً عملياً من خلال اختبار (60) عينة أنبوبية لتعطي نسب توسيع مختلفة تصل إلى (40%) تقريباً، وبزوايا نصفية لقوالب التشكيل تراوحت ما بين زوايا صغيرة ومتوسطة وكبيرة وهي (30° , 20°, 10°) علاوة على كون العينات ذات أربعة اسماك نسبية مختلفة هي (0.2 , 0.15 , 0.1 , 0.05) كما وتضمن الدراسة جانبا نظريا استند على كون الأنابيب ذات جدران سميكة للتنبؤ بعلاقة الإجهاد التشكيل النسبي مع نسبة التوسيع ، وتضمنت الدراسة تأثير خاصية الأصلاد الانفعالي الأمر الذي يكسب هذه الدراسة أهمية في كيفية التعامل مع هذه الخاصية. أثبتت الدراسة توافقاً جيداً بين الجانبين النظري والعملي وخصوصا في تحديد إجهاد التشكيل النسبي مع نسبة التوسيع، وبينت الدراسة أن إجهاد التشكيل النسبي يزداد كلما زادت نسبة التوسيع والزاوية النصفية لقوالب التشكيل وقد تراوح بين (0.7-0.1) للعينات ألمختبره علماً إن تأثره بنسبة التوسيع كان أكبر بكثير من تأثره بالزاوية النصفية بينما قل إجهاد التشكيل كلما زاد السمك النسبي لنفس نسبة التوسيع والزاوية النصفية لقلب التشكيل.


Article
DESTABILIZATION HEAT TREATMENT EFFECT ON EROSIVE WEAR CHARACTERISTICS OF HIGH CHROMIUM WHITE CAST IRON

Authors: Ali H. Ataiwi --- Israa F. Yousif
Journal: KUFA JOURNAL OF ENGINEERING مجلة الكوفة الهندسية ISSN: 25230018 Year: 2018 Volume: 9 Issue: 2 Pages: 45-56
Publisher: University of Kufa جامعة الكوفة

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Abstract

In the present investigation, erosive wear property of high chromium white cast irons (HCWI) is reported. HCWI were destabilized at two different temperatures of 955oC and 1100°C, air cooling followed by tempering heat treatment at 400°C and 700°C at each destabilized temperature. Erosion damage was evaluated by the removed material mass at impact angle 45° and time of 10 Hours. The surface metal flow was observed. Surface morphology of each specimen was characterized with scanning electron microscopy (SEM). The effect of heat treatment on differences in wear features of specimens is discussed. Experiment showed that the erosion rate of specimen destabilized at 1100°C, air cooled followed by tempering at 400°C air cooling is the best than other treatments. The hardness of test surface by this treatment increased from the initial 57 to 58 HRC after 10 hour. It showed that austenite in the surface structure has been transformed to martensite , which hardened the surface. Similarly, work- hardening effect also occurred on specimen destabilized at 955°C, air cooled followed by tempering at 400oC, air cooling to make its surface hardness increased to 59 HRC. It was shown that HCWI series heat treated at 955°C and 1100°C and tempered at 400°C have a very good erosive wear resistance and they are expected to find wide application as wear-resistant materials.

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