Turbine housing turned red hot
Raw Turbine Casting
Turbocharger cast parts for new high-performance engines require a material that is coordinated to the component behaviour, not least due to the aim to reduce exhaust gases and improving the performances. The requirements for these highly stressed casting components rise as the unit size and performance capability increase.
Regarding the exhaust gases, the turbine wheel in the turbine housing absorbs the energy from the exhaust gases and mechanically transmits it to the compressor via a shaft. The turbine wheel can turn with a speed of 160,000 to 300,000 rpm. In a spark-ignition engine, exhaust gas high temperatures must be endured in the area of the turbine housing. The turbine wheel, the bypass flap and the heat shield also reach correspondingly high temperatures. The heat shield prevents the heat from penetrating into the bearing housing.
The turbine housing is of key importance here, as it is placed under extremely high thermal stress and is also the most expensive component due to its size, complexity and material. The caster is confronted with thin housing walls, highly elaborate to fine structures with high temperature gradients within the component, and frequent temperature changes during operation. In addition, the turbocharger is also produced as a combined component in combination with the exhaust manifold nowadays. Under full load, the entire component is exposed to extreme thermal and mechanical stress. The fact that it becomes red-hot underlines this. Years of experience and the use of state-of-the-art design and simulation methods are necessary to meet these requirements.
Poor quality of turbine housing material will lead to premature failure such as
thermal cracking, creep or oxidation.
Cracked turbine housing
Rubbing or distortion of turbine housings due to over-heating
Niitsu has always been using ductile iron turbine housing
due to its high temperature endurance.
However, in order to keep on par with current technology, Niitsu HiT© turbine housing were developed to meet the increasing demands for high strength Ductile Irons capable of operating at high temperatures in applications such as exhaust manifolds or turbocharger casings. The primary properties required for such applications are oxidation resistance, structural stability, strength, and resistance to thermal cycling. Niitsu HiT© turbine housing will be applied for certain applications such as Caterpillar, Komatsu (KTR series), Cummins and etc.