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تاثير المعاملة بالليزر على مقاومة التاكل للفولاذ المقاوم للصدا نوع 304 == Effect of Laser Treatment On Corrosion Resistance of 304 Stainless Steel
Author name:
زمن عبد الرزاق عبد الوهاب
Supervisor name:
محمد جاسم كاظم | سامي ابراهيم جعفر
General topic:
Production engineering metallurgy and materials
Specific topic:
Metals Engineering
Degree:
Master
University:
University of Technology
Language:
English
University location:
Baghdad
First pages:
50T184 - p.pdf
Abstract:
تعتبر هذه الدراسة بانها محاولة لتحسين مقاومة التاكل للصلب المقاوم للصدا من نوع 304 عن طريق الانصهار السطحى بالليزر. تم استخدام تقنية منحني تافل لتحديد معدلات تاكل الصلب المقاوم للصدا نوع 304 في محلول 3.5? كلوريد الصوديوم عند اربعة حالات مختلفة. الاولى بدو | The present work represents an attempt to improve corrosion resistance of sensitized 304 stainless steel by laser surface melting treatment. Tafel extrapolation technique was used to determine the corrosion rates of stainless steel type 304 in 3.5% NaCl in four conditions. The first condition is as received, the second sensitized microstructures at temperatures 850 oC for one hour, the third condition is treating the stainless steel alloy by laser surface melting (LSM) without sensitization. The fourth condition is studying the effect of LSM on sensitized stainless steel.The main results obtained are expressed in terms of corrosion parameters through electrochemical behavior : E°, I°, E Corr., ICorr., EP., IP, EPit. and IPit.These parameters are strongly dependent on the microstructures of the alloy. The results reveal when the potentials increase, this means that the microstructure becomes thermodynamically more stable and has good corrosion resistance. The above electrochemical parameters for sensitized 304 stainless steel show that localized corrosion rate increases due to precipitation of chromium carbides on grain boundaries and to the sensitization process affecting the phases. The LSM treatment shifts the potential toward noble direction, the corrosion current densities values shift to lower values. Generally, a change in surface hardness shows a microstructure modification in metallic bonds. The comparison of anodic polarization curves indicates that the corrosion rates for laser treated specimens are reduced. Increase in corrosion resistance probably means that most inclusions at the surface have been dissolved in the structure due to melting or alternatively, they are covered by molten materials. An interesting feature is the systematic shift of the pitting potential in the noble region with a laser treatment. This result confirms that the laser treatment can be used successfully to improve the localized corrosion resistance.
