The aim of this paper is optimizing of parameters can be affected to depth of nitrided layer for improving the corrosion resistance of DIN 1.2344 low alloy steel by plasma nitriding.In this study, DIN 1.2344 low alloy steel samples were plasma nitrided at 3 level temperatures (450, 500 and 550℃), 3 level time (2, 4, 6 hour) and in 2 level gas compositions (25%N2-75%H2 and 75%N2- 25%H2). Diffusion zone was determined by optical microscopy. Phases formed in these layers were studied by X-ray diffraction method. The XRD pattern reveals that all specimens consist Fe3N, Fe2N and Cr2N phases.Results have shown that depth of diffusion zone increases byincreasing gas compositions from 25% N2 to 75% N2. In addition, thickness of this layer have increased by increasing temperature from 450℃ to 550℃, but It seems that by increasing nitriding time of 2 to 4 hour the depth of the white layer increased but by increasing to 6 hour the depth of this layer decreased sligthly. The optimun condition for plasma nitriding of DIN 1.2344 is 550℃, 4h and 75% N2.
One of the most important problems of transportation and reservoir of crude oil and gas liquids is corrosion of pipelines. The corrosion of pipeline has been caused deposition and contamination of groundwater and will be irreparable damage to environmental. Different methods are used for increasing the corrosion resistance of steel pipes.Nitriding is a surface treatment technique used to introduce nitrogen into metallic aterials to improve their surface hardness, mechanical properties, as well as wear and corrosion resistance and .In the plasma- nitriding process, by means of a glow-discharge using a mixture of N2 and H2, with the steel at the High constant temperature, nitrogen can penetrate the surface and diffuse into the steel and wear and corrosion resistant layer will be formed.This layer, which is called ‘‘white’’ or ‘‘compound’’ layer can consist of iron nitride phases, gamma prime, Fe4N, or epsilon, Fe2–3N .The diffusion zone with its induced compressive esidual stresses, enhances fatigue strength of the work piece. Detail of plasma nitriding process and its parameters have been described by Kovacs and Russell .
Publisher : 2nd National Iranian Conference on Gas Hydrate (NICGH)
By : H. Khorsanda , H. Aghajanib, N. Mohamadiana, A. Akrami
File Information: English Language/ 6 Page / size: 570 KB
سال : 1392
ناشر : دومین کنفرانس ملی هیدرات گاز (NICGH)
کاری از : خرسندی ,اقاجنیب ,محمدیان , اکرمی
اطلاعات فایل : زبان انگلیسی / 6 صفحه / حجم : KB 570