Dr. B. Pathiraj
Ir. Wei YA (contact person)
February-2011 – February 2015
Laser cladding, laser profile, powder density, residual stress, clad defects
The main aim of this project, funded by the Materials Innovation Institute (M2i) research program, is to develop production methods and tools needed to achieve a high degree of reliability and integrity of the laser cladded components and simultaneously attaining high laser cladding (production) rates. Such methods and tools should be amenable to easy implementation and integration in manufacturing industry and be suitable for different materials combinations without the need for any trial and error approach.
Industries often experience that clad layers develop cracks either during production (hot cracking) or during storage (delayed cracking) or during subsequent machining or in service due to relaxation of residual stresses. The high cooling rates and differential shrinkages involved in the laser cladding process are responsible for such tensile residual stresses which can easily exceed the yield strength of the clad material resulting in cracking and/or deformations.
Thermal and thermo-mechanical FEM models capable of predicting melt pool characteristics, clad geometry, distortion and cracking due the thermal stresses and their gradients as a function of the laser processing parameters will be developed and experimentally validated. Such models will provide guidelines for the development of the feedback controller of the cladding system and other tools. A database (DB) architecture will be designed such that it will be able to suggest suitable laser processing conditions for the chosen material combination and clad characteristics. All existing data and results of this research will be incorporated for industrial use.
a) Modeling geometry of clad layer; b) First threshold of laser cladding.
Relations between laser processing conditions (power, cladding speed, laser beam size and shape, powder feed rate, initial substrate temperature) and the resulting clad properties (clad geometry – height & width, micro-structure, hardness, dilution at the interface region, residual stresses, wear at ambient and elevated temperatures and any other relevant properties) will be studied. Such relationships will be established for different substrate/clad materials combinations typical in industry.
Residual stress evaluation of the samples produced under optimal and extreme conditions
The project is funded by M2i and Stork Gear and Service B.V..