Microstructure and Mechanical Properties of Large-diameter and Large-deformation Middle-frequency Induction Pipe Bend of 16Mo3 Steel

The large-diameter and large-deformation 16Mo3 steel pipe bend was made by means of the middle-frequency induction bending procedure through heating a narrow circumferential band around the pipe, of which the pipe size was 790 mm×30 mm, the relative bend radius was 1.8 and the bend angle was 70°. The pipe bend was inspected and then sampled to examine the microstructure and test the mechanical properties. The results showed that the wave shape degree, ovality and wall thinning rate of the bending portion could meet the requirement of the corresponding standard, the microstructure of the bend was ferrite+pearlite+little carbide and no intergranular cracks, tensile and impact properties in room temperature and 500 ℃ tensile properties were in accordance with the corresponding standard, the test results of the pipe bend mechanical properties in different location of the bending portion were uniform and in the same level as the pipe raw material properties.