Abstract
The 12CrNi2 alloy steel powder studied in the present paper is mainly used to manufacture camshafts for nuclear power emergency diesel engines. Laser cladding deposition is of great significance for the manufacture of nuclear power emergency diesel camshafts, which has the advantages of reducing material cost and shortening the manufacturing cycle. However, due to the extremely uneven heating of the components during the deposition process, a complex residual stress field occurs, resulting in crack defects and residual deformation of the components. In the present paper, 12CrNi2 bulk specimens were prepared on the Q460E high-strength structural steel substrate at different preheating temperatures by laser cladding deposition technique, and a finite element residual stress analysis model was established to investigate the effects of different preheating temperatures on the microstructure, properties, and residual stress of the specimens. The results of the experiments and finite element simulations show that with the increase of preheating temperature, the content of martensite/bainite in the deposited layer decreases, and the ferrite content increases. The proper preheating temperature (150 °C) has good mechanical properties. The residual stress on the surface of each specimen decreases with the increase of the preheating temperature. The longitudinal stress is greater at the rear-end deposition part, and the lateral residual stress is greater on both sides along the scanning direction.
Highlights
Traditional technologies for the manufacturing of nuclear power emergency diesel engine camshafts are forging machining, post-forging heat treatment, etc
The longitudinal stress is greater at the rear-end deposition part, and the lateral residual stress is greater on both sides along the scanning direction
The 12CrNi2 metallic powder-based laser cladding deposition studied in the present paper will be mainly used for the production of camshafts for nuclear power emergency diesel engines, which provides a theoretical basis for ensuring safe operation and independent development
Summary
Traditional technologies for the manufacturing of nuclear power emergency diesel engine camshafts are forging machining, post-forging heat treatment, etc. From three aspects including the ratio of depth to width, laser energy density, and material dilution ratio, a characterization method of three-dimensional cladding layer was proposed, which provides a theoretical basis for the shape control of laser metal direct forming [5]. For the residual stress problem of laser metal direct forming, substrate preheating is an effective stress control method for increasing the laser absorption rate of metal materials, reducing temperature gradients and cooling rate, and improving defects such as cracks. The changes in microstructure, properties, and residual stress of the materials under different preheating conditions were explored, which effectively improved the defects due to the overall unevenness in heating during laser cladding deposition, and enhanced its performance to a certain extent while being applied in the process of manufacturing of nuclear power emergency diesel engine camshafts by laser cladding deposition
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