In quenching process many parameters have an effect on this process such as steel type, quenching medium type, quenching medium temperature and the volume of the workpiece. In order to give a workpiece free of defect, it’s very important to understand the effect of these parameters on this process. In the present work a mathematical heat transfer model have been used to simulate the heat treatment (quenching process). This model used to investigate the temperature distribution in the workpiece at different time. A numerical scheme based on a control volume formulation and a computer program with C++ language was used to solve the set of heat transfer equations. The developed model was used also to evaluate the effect heat treatment parameters such as quenching media, carbon steel type and cross sectional area of the workpiece. The model also can be used to simulate the heat treatment process (quenching process) of various materials and alloys with different conditions. The results of the model were compared with experimental published data give good agreement.

هنالك عوامل كثيرة تسيطر على عملية الاصلاد بالتقسية والمنتج من هذه المعاملات ومن اهم هذه العوامل هي نوعية الفولاذ او نوع المعدن , نوع وسط التبريد ودرجة حرارته وكذلك حجم القطعة المعاملة حراريا.لذلك من الضروري جدا معرفة تاثير هذه العوامل للحصول على منتج خالي من العيوب قدر الامكان وباقل جهد عملي. في هذا البحث تم وضع انموذج رياضي لوصف عملية الانتقال الحراري خلال عملية الاصلاد بالتقسية لانواع مختلفة من الفولاذ , حيث تم استخدام هذا الانموذج المقترح لمعرفة وفحص توزيع درجات الحرارة في القطع المعاملة حراريا وتاثير العوامل المذكورة في اعلاه وبالفترات الزمنية المختلفة. تم استخدام الطرق العددية لايجاد الحلول النهائية للمعادلة الخاصة بابانموذج الرياضي وكذالك تم بناء برنامج بلغة الـ C++ لايجاد الحلول لهذه المعادلات.باستخدام هذا النموذج تم دراسة تاثير العوامل التي تتحكم بالمعاملات الحرارية بصورة عامة وعملية الصلاد بصورة خاصة وقد استخدم هذا الانموذج ايضا بدراسة عملية الاصلاد لمعادن اخرى غير الفولاذ حيث اظهرت المقارنة بين نتائج البحث الحالي مع نتائج عملية منشورة اظهرت تطابق جيد بينهما.

Quenching --- heat transfer --- mathematical model.

The goal of this study is to specify the optimal factors for the hardening process (tempering temperature, the percentage of nanoparticles, type of base media, nanoparticles type and tempering time) in order to maximize the hardness of medium carbon steel by using Taguchi technique. An (L18) orthogonal array was chosen for the design of the experiment. The optimum process parameters were determined by using signal-to-noise ratio(larger is better) criterion. The important levels of process parameters on hardness were obtained by using analysis of variance which applied with the help of (Minitab17) software to investigate the effect of parameters on the hardness. Percentage of volumetric fractions of nanoparticles with three different levels (0.01, 0.03 and 0.08%) was prepared by dispersing nanoparticles that are (α-Al2O3, TiO2 and Cuo) with base fluids (De-ionized water, salt solution, and engine oil). Medium carbon steel specimens were suffered to hardening and tempering heat treatment process. Tempering temperature was (400℃, 550℃) for (30,45and 60 minutes). Results ended up with a conclusion that tempering temperature (400℃) had the major influence on hardness behavior then type of nanoparticles (TiO2) followed by time tempering (30min) then base media (salt solution) and finally volume fraction of nanoparticles (0.03%).

Nanofluids --- quenching --- hardness --- Taguchi technique.

A study has been made to evaluate wear behavior of AISI 52100 steel underdifferent quenching media. This investigation was accomplished by two stages. Inthe first stage of the study , quenching treatment was applied to the steel alloy andthen cooling was carried out in various media (Oil , Polyvinyl Alcohol , Glycerol),and finally low temperature tempering (200Co) was applied to the quenchedsamples to eliminate internal stresses after transformation from austenizationtemperature to the temperature which the samples were cooled. Microstructuralexamination was achieve using light microscopic for all heat treated specimens aftermetallographic preparations . In the second stage , pin - on - disk technique wasused to determine the wear rate of the treated specimens depending on weight lossmethod . Worn surfaces of the steels were examined using light microscopic tocharacterize the topography of the surfaces.The results exhibited that (i) Martensitic matrices with retained austenite can beobtained depending on the quenching medium . (ii) Chromium carbides have beenprecipitated as a result of quenching heat treatment in different quenchants . (iii)Quenching in oil and then tempering revealed wear resistance more than otherquenchants . (iv) wear cracks were presented on the worn surfaces of the steelswhich was used in this work .

Quenching Media / Wear resistance /AISI 52100 Steel

The purpose of this study is designate quenching and tempering heat treatment by using Taguchi technique to determination optimal factors of heat treatment (tempering temperature, percentage of nanoparticles, type of base media, nanoparticles type and tempering time)for increasing ultimate tensile strength, yield strength and ductility properties of medium carbon steel. An (L18) orthogonal array was chosen for the design of experiment. The optimum process parameters were determined by using signal-to-noise ratio (larger is better) criterion. The importance levels of process parameters on tensile properties were obtained by using analysis of variance, which applied with the help of (Minitab18) software. Percentage of volumetric fractions of nanoparticles with three different levels(0.01, 0.03 and 0.08 %) were prepared by dispersing nanoparticles that are (α-Al2O3,TiO2 and CuO) with base fluids (De-ionized water, salt solution and engine oil).Medium carbon steel specimens were suffered to hardening and tempering heat treatment process. The variables of tempering heat treatment were temperatures (400 C˚, 550 C˚) and a soaking times (30, 45 and 60 minutes) respectively. Tensile testing performed on samples using united universal hydraulic machine. The results for ( S/N) ratios showed the order of the factors in terms of the proportion of their effect on ultimate tensile strength, yield strength and ductility properties as follow: Tempering temperature ( 400 C˚) ,Nanoparticles type (TiO2 ),Tempering time (30 min),Type of base media (salt solution, engine oil) and Percentage of nanoparticles ( 0.03%) was the least influence for ultimate strength and yield strength while for the elongation were as follows: Tempering temperature (550 C˚),Tempering time(60min), Nanoparticles type (CuO),Type of base media (deionized water) and last percentage of nanoparticles (0.08%).

Nanofluids --- quenching --- tempering --- tensile properties --- Taguchi technique.

The Al-Cu aluminum alloys are primarily used in the aerospace industry as structural components. This study aim to improve properties of Al-4.3%, Cu-0.7%, Fe-0.6%, Mg alloy such as compression resistance, thermal stability and microstructure by quenching in 30% polyethylene glycol. Results showed that compression resistance improved by (10%) when quenching in 30% polyethylene glycol corresponding to the base alloy (quenching in water) when aging at 175 ºC for 3 hour. Also results showed that the thermal stability improved when quenching in polyethylene glycol.

إن سبيكة (Al-Cu) مِنْ ِ سبائكِ الألمنيومِ التي تستعملُ في صناعة المركبات الفضائيةِ كمكوّنات هيكلية . إن الهدف من هذه الدراسةِ هو تَحسين خواص سبيكة (Al-4.3%Cu-0.7%Fe-0.6%Mg) مثل مقاومة الانضغاط , الاستقرارية الحرارية من خلال استخدام الإخماد في البولي اثيلين كلايكول لهذه السبيكةِ. أظهرت النتائج إن السبيكة يحدث فيها تحسنا كبيرا في الاستقرارية الحرارية وكذلك تحسن في مقاومة الانضغاط بنسبة (10%) عند الإخماد في (30%) من البولي اثيلين كلايكول بالمقارنة عند الإخماد عند إجراء التعتيق في درجة ºC 175 .

Effect of Quenching --- Polyethylene Glycol --- PAG --- Aluminum Alloy