Effect of Laser Clad Repair on Crack Growth Rate of TC4 Titanium Alloy
GE Maozhong1, XIANG Jianyun2, FAN Zhen1
1 School of Materials Engineering, Jiangsu University of Technology, Changzhou 213001; 2 Mould Department, Changzhou Vocational Institute of Light Industry,Changzhou 213164
Abstract: To investigate the effect of laser clad repair on crack growth rate of TC4 titanium alloy, surface groove of TC4 titanium alloy plate was repaired by adding TC4 titanium power layer by layer based on laser cladding technology. The microstructure and fracture surface morphology were characterized by optical microscopy and scanning electron microscopy, respectively. Fatigue crack growth experiment was used to obtain the crack length and cycle number. A modified incremental polynomial method was used to obtain the fatigue crack propagation rates of three samples per group under the same crack length. Experimental results indicated that the laser repairing zone was composed of β grains and α phase precipitating along the grain boundary, which belonged to typical Widmannstatten. The heat effect zone consisted of equiaxed α grains and β transformed structure, which was known as two-state structure. Comparing with the original sample, the fatigue crack growth rate of the laser cladding repaired samples was obviously decreased. The improvement of fatigue crack growth rate resistance for laser cladding repaired TC4 titanium alloy was attributed to a combination of high fracture toughness of Widmannstatten and the comprehensive mechanical properties of two-state structure.
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2018, Vol. 32 
