Analysis of Microstructure,Properties and Fracture Mechanism of Stainless Steel Pipeline Repaired by Laser Deposition
The 316L stainless steel powder was selected for different process parameters of 316L stainless steel nuclear power pipeline by laser deposition,and the macroscopic morphology and microtissue of the repair area were measured by microhardness meter and tensile test machine.The fatigue test machine was used to repair the fatigue life of the sample at different scanning speeds,and the morphology characteristics of the fracture port were characterized via SEM.The results show that the repair area is composed of fusion zone and cladding zone,which is composed of cell crystal,column crystal and branch crystal,and the fusion zone presents a mesh crystal structure.The microhardness distribution showed fusion zone＞cladding zone＞thermal influence zone＞substrate.Within a certain range,with the increase of laser power,the decrease of scanning speed and powder delivery rate,the grain size gradually increases,the microhardness of the repair area decreases,and the hardness of the thermal influence area shows an increasing trend.When the laser power is 1 300 W,the scanning speed is 9 mm/s,the powder feeding rate is 0.5 g/min,the sample elongation is 61.61％,and at the 400 MPa stress level,the cycle number is 67 225 times.Due to its good macroscopic morphology,refined crystals in the repair area,and a small degree of processing hardening,the samples showed good plasticity and fatigue resistance,and had optimal mechanical properties.
NETL
NSTL
万方数据
维普
