Dissertation
Dissertation > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallic materials > Steel > Special performance of steels > Stainless steel, acid-resistant steel

445M ferritic stainless steel performance

Author Gu
Tutor ZhanZhaoZuo;RongFan
School Kunming University of Science and Technology
Course Materials Processing Engineering
Keywords Ferritic stainless steel Alloying elements Precipitated phase Corrosion Pitting corrosion
CLC TG142.71
Type Master's thesis
Year 2011
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Paper reviewed the development status of the ferritic stainless steel, relying on the National Science and Technology Pillar Program, focused on the advanced production line of stainless steel in China and the development of advanced production technology, developed a new type of ferritic stainless steel, and study its impact toughness and corrosion. By test design ferritic stainless steel components, and to study the impact of alloying elements on the toughness and corrosion resistance of ferritic stainless steel. This novel ferritic stainless called 445M ferritic stainless steel containing Cr amount of 20-24%, the amount of Mo-containing 1-2%, and added an appropriate amount of Ti and Nb, by adjusting these The content of the element, and ultimately it has good application performance to meet the requirements of the different parts of the properties of the materials. The paper by the impact test, scanning electron microscopy and transmission electron microscopy analysis of the Impact Toughness 445M ferritic stainless steel cold rolled sheet, cold-brittle transition temperature and different solid solution treatment temperature and precipitation in the steel relative to its hot-rolled plates. The results showed that the stainless steel cold-rolled plate the cold brittle transition temperature between -40 - 60 ℃; toughness of hot-rolled plates after 850 ~ 900 ℃ temperature after solution treatment; 445M ferritic stainless steel Nb will give priority to the formation of TiC and Ti elements NbN and (Nb, Ti) (C, N) precipitated phase, they hinder the precipitation of chromium-rich Cr23C6 to improve the toughness of ferritic stainless steel; 445M ferritic stainless steel M6C carbides precipitation, σ Laves and × phase is a major factor in the decline in the toughness of stainless steel. Papers crevice corrosion, pitting corrosion and electrochemical corrosion corrosion investigated alloying elements such as Mo and Cr 445M ferritic stainless steel corrosion resistance, and contrast material 316L austenitic stainless steel. The experimental results show that, Cr, Mo, and other elements is to improve the corrosion resistance of stainless steels in the corrosive medium containing Cl-main alloying element, wherein the Cr element is rapidly formed on the stainless steel surface layer is very dense and stable chromium oxide passivation film, Mo elements to promote the passivation film Cr3 further enrichment, to make stainless steel passivation film is more dense, and better protection, thereby greatly enhancing its corrosion resistance; than 316L austenitic stainless steel, 445M ferritic The corrosion resistance of stainless steel can be more excellent. Thesis through the analysis of the above test results, and ultimately determine 445M ferritic stainless steel alloy composition. The stainless steel not only has excellent corrosion resistance and good toughness, and related test to prove its performance to meet the engineering application.

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