Fatigue life of exhaust manifolds including corrosion and creep interaction

Important results from the project

The overall goal is to focus on the combined effects of creep and corrosion on fatigue life and thereby contribute to reliable material-data and material-model for the development of exhaust components. The scientific highlight is a deep understanding of high-temperature fatigue, including the influence of corrosion and creep. During 2.5 years, the project has delivered 6 scientific publications and two doctoral dissertations. A prototype turbo manifold has been developed and tested in a motor cell. The goal of the project is met.

Expected long term effects

Expected results are new material data. The results are expected to lead to deep understanding of the interaction between corrosion, fatigue and creep on high temperature cast materials. The expected effect is contributing to the development of energy-efficient propulsion by facilitating the development of exhaust components for future energy-efficient engines. Scania is an important global heavy-duty vehicle manufacture. A reduction in each engine´s CO2 emissions has the potential to reduce global emissions overall.

Approach and implementation

The project is led by Scania and the main staff are two doctoral students at KTH. In work package 1, three creep test methods, constant load test, sequential tensile test and stress relaxation with thermal cycling have been used to study the creep mechanism. Sequential tensile test was performed at VW Research Group. Constant load test was performed by Swerim AB. In work package 2, LCF-test in controlled environments has been run on KTH´s equipment. The microscopic damage mechanisms and synergy effects of fatigue, corrosion and creep were studied in cooperation between KTH and Scania.