Analiza przyczyn powstawania przebarwień na powierzchni elementów układów wydechowych wykonanych z aluminiowanych rur ze stali chromowej

• Autorzy: Żaba K. , Nowak S. , Wróbel M.

Warianty tytułu

EN

Analysis of causes of defects occurrence in a form of a tarnish on surfaces of exhaust system elements made of aluminized steel tubes

• Języki publikacji: PL

Abstrakty

PL

Przedstawiono wyniki badań eksploatowanych elementów układów wydechowych oraz taśm ze stali chromowej gatunku 1.4510Al z powłoką Al-Si o grubości ok. 80 g/m2, ukierunkowanych na poszukiwanie przyczyn nieakceptowanych przebarwień. Wykonano obserwacje makroskopowe powierzchni powłoki przed i po eksploatacji oraz mikroskopowe za pomocą mikroskopu optycznego i skaningowego. Wykonano mikroanalizy składu chemicznego podłoża i powłoki. Określono grubość powłoki, jej stan i poziom jej stabilności. Na próbkach blachy wsadowej wykonano badania efektów nagrzewania w podwyższonej temperaturze. Wykonano badania korozyjne w komorze solnej.

EN

Requirements, which should be satisfied by tubes intended for exhaust system elements, are determined by the vehicle users and by the plastic shaping of tubes. These requirements are, first of all, corrosion resistance, tightness and plasticity, which warrant compliance to deformations in processes of tubes formation - bending, expanding, etc. Exhaust systems are exposed - in operational conditions - to the influence of various corrosive factors, such as among others, environments containing Cl, SO4 and different contaminations, decreasing their working time. The corrosion resistance should be guaranteed by the proper steel grade or protecting coatings. Mainly tubes of low-carbon steel with a coating and of chromium steel also with coatings are used for the production of exhaust systems. Investigations performed for the exhaust system fragments of chromium steel 1.4510Al with the Al-Si hot-deep coating of a thickness of app. 80 g/m2, and on strips intended for tubes are presented in the paper. The characteristic feature constitutes an occurrence of the diffusive Al-Fe-Si layer, between the coating and base, influencing a good adherence and a high corrosion resistance. Thus, due to a significant chromium content (more precisely: chromium oxide coating) and additional strengthening by the Al-Si coating (more precisely: aluminium oxide coating) a certain kind of natural corrosion resistance should be expected. However, operational tests - performed under the supervision - did not confirm such expectations. Thus, it was found that, after using the exhaust systems at maximum surface temperatures 550-600 [degrees] C when gases flowing via the exhaust system were of a temperature of 800 [degrees] C, certain tarnishes occurred on the external surfaces. These defects appeared already after a few thousand kilometers of operation, causing the exhaust system quality questioning by the clients. In order to explain the reasons of the tarnish formation on tube fragments the macroscopic observations of the coating surface after the exploitation as well as the microscopic observations of these surface were performed by means of the optical microscope and by the scanning electron microscope equipped with the microanalyser of the chemical composition. The coating thickness was also estimated. In addition the tests of the heat treatment for strips from which exhaust system tubes were made. The heat treatment influence on surface changes of coatings and corrosion resistance were estimated. The obtained results are presented as photographs, diagrams and tables.

Słowa kluczowe

PL

odporność korozyjna; układ wydechowy

EN

corrosion resistance; exhaust system

• Wydawca: Wydawnictwo SIGMA-NOT
• Czasopismo: Rudy i Metale Nieżelazne
• Rocznik: 2011
• Tom: R. 56, nr 4
• Strony: 187--195
• Opis fizyczny: Bibliogr. 7 poz., rys., tab., fot.

Twórcy

autor

Żaba K.

autor

Nowak S.

autor

Wróbel M.

• Akademia Górniczo-Hutnicza, Wydział Metali Nieżelaznych

Bibliografia

• 1. ASTM A463/A463M – 06: Standard Specification for Steel Sheet, Aluminum‐Coated, by the Hot-Dip Process.
• 2. ASM Handbook: Surface Engineering, ASM International, Handbook Committee, 1994, t. 5, s. 346.
• 3. EN 10346:2009: Continuously hot-dip coated steel flat products. Technical delivery conditions.
• 4. Inoue Y., Kikuchi M.: Present and Future Trends of Stainless Steel for Automotive Exhaust System. Nippon Steel Technical Report No. 88, 2003, s. 62- 69.
• 5. Wang Chaur-Jeng, Chen Shih-Ming: The High-temperature Oxidation Behavior of Hot-dipping Al+Si Coating on Low Carbon Steel. Surface and Coatings Technology, 2006, t. 200, nr 22‐23, s. 6601- 6605.
• 6. Żaba K.: The influence of annealing temperature and time on the structure and features of the Al+Si coatings on steel sheets, purposed for pressured welded pipes applied in exhaust systems. Archives of Civil and Mechanical Engineering, 2009, t. 9, nr 2, s. 145-152.
• 7. Żaba K.: The influence of temperature and time of exhibition on a change of Al+Si coating thickness and surface texture on the steel plates. Archives of Metallurgy and Materials, 2010, t. 55, nr 1, s. 151-162.