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Register a new userEffect of Aging Heat Treatment on Pitting Corrosion Resistance of Martensitic Stainless Steel
تأثير المعالجة الحرارية بالتعتيق في مقاومة التآكل الكيميائي النقري للفولاذ المارتنسيتي المقاوم للصدأ
1975
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محمد يعقوب( باحث )
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إن الهدف من هذا البحث هو دراسة تأثير المعالجة الحرارية بالتعتيق في مقاومة التآكل الكيميائي النقري للفولاذ المارتنسيتي المقاوم للصدأ إلى معالجة انحلالية عند درجة حرارة 1050درجة مئوية مدة ساعة و غطِّست بالماء سخَِّنت إلى درجة حرارة ضمن المجال(400-750) درجة مئوية لمدد إبقاء متنوعة (1-16) ساعة .. أُجري اختبار التآكل الكيميائي المسرع و اختبار التآكل الكيميائي بالغمر على العينات بعد المعالجة الحرارية. بينت نتائج البحث تأثر مقاومة التآكل النقري تأثرًا كبيرًا بدرجة حرارة التعتيق، إِذ وجد أن العينات المعتقة عند درجة حرارة 475 درجة مئوية تملك معدل تآكل أعظميًا الذي قد يكون بسبب زيادة نسبة فرايت نوع دلتا و ترسبات ناعمة جدًا من أطوار أخرى بشكل غير متجانس في الطور الأساسي المارتنسيتي؛ مما يؤدي إلى زيادة معدل التآكل في حين العينات المعتقة في مجال درجة حرارة ( 550-625 ) درجة مئوية لها قيم معدل تآكل أصغرية، و يعزى ذلك إلى النسبة الحجمية المرتفعة للأوستنيت المتبقي. و تبدي العينات المعتقة عند درجة حرارة أعلى من 625 درجة مئوية معدلَ تآكلٍ متوسطًا. و وجد كذلك أن نوع النقر الناتجة عن كلا اختباري التآكل الكيميائي و شكلها لا يتعلق بشكل الفريت نوع دلتا و الكربيدات الموجودة في البنية المجهرية.
The aim of this work is to study the effect of the aging heat treatment on the pitting corrosion resistance of martensitic stainless steel. In this research a number of specimens from martensitic stainless steel were subjected to solution treatment at 1050 for one hour followed by water quenching then aging in the temperatures range (400-750) for different holding times (1-16 hrs). After heat treatment, two types of corrosion tests (accelerated test and immersion test) were conducted. The results obtained in this research showed that the pitting corrosion resistance was affected by Aging temperature and three critical temperatures were found in corrosion test: the specimens aged at 475 0C had maximum corrosion rate. This may be due to the presence of stringer δ- ferrite and precipitation of very fine precipitates which precipitated heterogeneously in the martensitic matrix, which led to an increase in corrosion rate. The specimens aged at temperatures range (550 – 625) 0C had minimum values of corrosion rate, this is attributed to the high volume fraction of retained austenite. The specimens aged at temperatures above 625 had intermediate corrosion rate. The type of pits, which resulted from two pitting corrosion tests, was independent form the form of δ-ferrite and carbides which presence in microstructure.
References used
B. Tzaneva, “Effect Of pH ON The Corrosion Behaviour Of High Nitrogen Stanless Steel In Chloride Medium,” Journal of Chemical Technology and Metallurgy, 48, 4, 2013,pp 383- 390
R. C. Newman, “Understanding the Corrosion of Stainless Steel,” Corrosion, Vol. 57, No.12, Dec., 2001, pp1030-1041
. B. Miao, et al., “Microstructure of Tempered AISI 403 Stainless Steel,” Material Science and Engineering, A171, 1993, pp 21-33
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