Comparison of the high-temperature corrosion-fatigue resistance of cast alloys for exhaust manifolds

• The corrosion fatigue behavior, fatigue resistance and corrosion resistance of four materials used in exhaust manifolds have been evaluated through conducting low-cycle fatigue tests at 800oC in synthetic exhaust and argon atmospheres as well as oxidation tests in the exhaust atmosphere. The four materials are two ferritic ductile cast irons SiMo51 and SiMo1000, one austenitic ductile cast iron Ni-resist D5S and one austenitic cast stainless steel HK30. Quantitative material rankings were given for the four materials in the two atmospheres through comparing the corresponding e-N and S-N curves. The crack growth mechanisms of the austenitic materials were studied in detail in the paper. Brittle intermetallic phases have been found in both materials but observed to have different levels of impact on their corrosion fatigue properties. The Ni-, Mn-, Si-rich intermetallic phase found in D5S greatly affects both fatigue and corrosion behavior of this material. However, the Fe-,Cr-rich sigma phase shows an insignicant impact as the crack growth path only occasionally follow the distribution pattern. In addition, severe oxide spallation was found in D5S leading to a rapid weight loss during the oxidation test.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Metallurgi och metalliska material (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Metallurgy and Metallic Materials (hsv//eng)

Nyckelord

Corrosion fatigue

ductile cast iron

cast stainless steel

high temperature

low-cycle fatigue

controlled atmosphere

sigma phase

Materials Science and Engineering

Teknisk materialvetenskap

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)