Improved Wear Resistance of Austempered Gray Cast Iron Using Shot-Peening Treatment 2020-01-1098
In this research, ball-on-plate reciprocating sliding wear tests were utilized on austempered and quench-tempered gray cast iron samples with and without shot-peening treatment. The wear volume loss of the gray cast iron samples was compared under equivalent hardness. The microstructure transformations in the matrix was studied using metallurgical evaluation and hardness measurement. It was found that thin needle-like ferrite became coarse gradually with increasing austempering temperature and was converted into feather-like shape when using the austempering temperatures at or above 343°C (650°F). No martensitic structure could be observed since full transformation to ausferrite has achieved. The residual stress on the surface and sub-surface before and after shot-peening treatment was analyzed using x-ray diffraction. Compressive residual stress was produced after shot-peening treatment and showed an increasing trend with austempering temperature. In sliding wear tests, austempered gray cast iron had lower wear volume loss than quench-tempered gray cast iron before and after shot-peening treatment. The wear tracks were examined using scanning electron microscopy. Abrasive wear and adhesive wear were believed to be the main wear mechanisms on the gray cast iron samples. The improvement of wear resistance after shot-peening was associated to the benefits of compressive stress preventing or retarding the nucleation and propagation of micro-cracks.
Yu Liu, Gary Barber, Weiwei Cui, Bingxu Wang
Oakland University, Zhejiang Sci-Tech University