Laser Welding Of TA2 And 40Cr Steel

This topic of TA2 and 40 Cr steel the laser welding test,analysis of the joint,after adding transitional metal welding of TA2 and 40 Cr steel,to determine the metal V,Cu composite transition layer,the V thickness from 0.3 mm to 0.7 mm,the thickness of Cu from 0.5 mm to 1.5 mm.The influences of different thickness combinations and different laser welding parameters on the joint structure and performance were studied.By optical microscope,scanning electron microscope,XRD analysis test means such as organization of joint and fracture morphology and phase analysis,through the tensile strength and microhardness test evaluates the mechanical properties of the joint.Using ANSYS software of TA2/40 Cr steel add 0.3mmV/1mmCu metal transition layer and add 0.7mmV/1mmCu transition metal layer of laser butt welding temperature field and stress field numerical simulation,and validated by the measured residual stresses on the simulation results.The results show that:In TA2/40 Cr steel butt joint to join 0.5mmV/0.5mmCu composite transition layer metal after laser welding,unable to realize TA2 and reliable connection of 40 Cr steel,namely before and after the welding joint crack,fracture in brittle Ti-Cu series compounds,but not found between Fe-Ti brittle compounds.When compound V in the transition layer thickness 0.5 mm unchanged,while Cu layer thickness from 0.75 mm to 1.5 mm,lower after joint strength increase first,laser power in TA2 side of 2.9 KW and 40 Cr steel side is 2.7 KW,composite transition layer is 0.5 mmV/1 mmCu intensity is the highest,reached 251 MPa.When the Cu layer thickness in the composite transition layer remains unchanged at 1.0mm,and the thickness of the V layer is below 0.4mm,it is difficult to achieve reliable connection between TA2 and 40 Cr steel.When the thickness of V layer is 0.7mm and the thickness of Cu layer is 1.0mm,the laser power is 2.7kw and 40 Cr at the side of TA2 with the highest intensity of 2.5kw,reaching 311 MPa.The addition of intermediate transition layer can alleviate welding stress,and on the other hand,it can effectively prevent the combination of Ti and Fe elements,thus avoiding the formation of Fe-Ti brittleness compounds,thus enhancing the strength of joints.In a certain range,the change of focus and offset can also affect the strength of the joints.A composite transition layer with 0.5mmV/1mmCu was adopted,and the laser power was 2.7kw and 40 Cr on the TA2 side and 2.5kw on the side,and the highest intensity was 313 MPa.In the case that the defocusing amount is 0 and the other conditions are the same,the strength of the offset joint is reduced to different degrees,and the maximum strength is 252 MPa when the offset is 0.3mm.The hardness of the joints fluctuates greatly.The highest degree of hardness is located in the heat affected zone near the 40 Cr steel side fusion line,and the highest reaches 800HV0.3.The second is the second weld center,which is about 450 ~ 550HV0.3.The lowest is the original V/Cu contact surface,only about 50HV0.3.In addition,the softening zone in the 40 Cr steel heat affected zone is also a region with low hardness.The simulation results of welding temperature field and stress field of TA2 and 40 Cr steel show that the temperature rise and decrease rate are very fast during laser welding,and the solidification process of weld is extremely unbalanced.The maximum longitudinal residual tensile stress and transverse residual tensile stress are located in the Cu/40 Cr steel welds of the 40 Cr side.When the composite transition layer of Cu layer thickness to 1mm,and V layer thickness from 0.3mm to 0.3mm,the maximum longitudinal residual tensile stress and transverse residual tensile stress has the obvious drop,therefore,under the condition of this topic in the test,using 0.7 mmV/1.0mmCu composite transition layer can obtain better welding joint quality.