Research On Weld Microstructure And Properties Of 3Cr13/DC01 Laser Welding

CO2 laser welding is widely used because of its good controllability,high power,high beam quality and long service life.In this paper,a 2mm-thick cold-rolled steel plate DCO1 was selected.After drilling,the steel plate was fitted with a 4mm diameter 3Cr13 cylinder for narrow clearance,and the CO2 laser with a power of 2.5KW,welding speed of 0.8mm/s and spot diameter of 0.5mm was used for welding.After welding,the microstructure showed that the microstructure was different in each forming zone.It was observed that the microstructure in the fusion zone was mainly columnar and elongated.Further observation showed that the columnar crystals grew along the direction from the fusion zone to the center of the weld.The surrounding tissues of the fusion zone were long and narrow dendritic crystals with disorderly growth,and the tissues at the center of the weld of 3Cr13/DCO1 were tiny equiaxed crystals.XRD phase analysis results show that the weld area is mainly composed of chromium manganese silicon,and there is a certain amount of CrMn3 in the weld area.CrMn3 has high hardness and good wear resistance,which improves the comprehensive performance of the material.Mechanics performance test including hardness test,fracture test,hardness results show that the microhardness of welds between parent metal microhardness,this is because 3Crl 3 material organization to martensite,and the weld microstructure of pearlite+martensite,pearlite has good toughness,the existence of pearlite hardness is reduced,but the toughness increases accordingly.The hardness of the weld area is not uniform,which is caused by the uneven martensite distribution.The results of scanning fracture analysis in the failure test showed that the fracture mechanism in the weld seam was mainly characterized by cleavage fracture and the base material by dimple fracture.The temperature field,thermal stress field of 3Crl3/DC01 in laser welding and stress field of 3Crl3 axis under different impact loads were studied by ANSYS numerical simulation software.The results of numerical simulation show that the temperature field remains quasi－steady during laser welding with the movement of heat source.The thermal stress in welding process increases with time.The maximum residual stress during cooling after welding is 13MPa,and the workpiece deformation is 0.014mm after welding.The residual stress received by the workpiece after welding is small,and the deformation of the workpiece is small.The stress under the load of 70N is 81.6MPa,and the yield limit of the material at the welding seam is 610MPa,which obviously cannot destroy the shape of the welding seam.The welding seam under the current parameters is of good quality.