Forming and uniformity of shaft parts without a stub bar by axial closed-open-type cross-wedge rolling

To realize cross-wedge rolling of shaft parts without a stub bar in a short process,an axial closed-open-type cross-wedge rolling technique was proposed.Based on the strain characteristics in the rolling,evaluation indices of deformation uniformity were provided,and the DEFORM-3D software was adopted to conduct numerical simulations of the rolling process.The metal flow and strain distribution in all stages of the rolling process were analyzed.It is shown that the strain value of the rolled piece close to the end is relatively high while the overall strain distribution is uniform in the rolling process.When the percentage reduction in area is smaller,the fluctuation range of the equivalent strain will be lower and the overall uniformity of the rolled piece will be better.A variable angle wedge was implemented to make metal flow inward and eliminate concavity.Finally,rolling experiment was performed,which indicate that the shape of the rolled piece obtained is consistent with the simulation results.Concavity value in the rolling is decreased by 92%as compared to conventional open rolling.The research results lay a theoretical basis for realizing closed-open-type cross-wedge rolling without a stub bar.

Effect of tempering on bonding characteristics of cross wedge rolling 42CrMo/Q235 laminated shafts

To further improve the comprehensive properties of 42CrMo/Q235 laminated shafts produced by cross wedge rolling.theheat treatment of the shafts was studied.Tensile and bending tests were carried out to compare the changes in mechanicalproperties before and after heat treatment.The results showed that the interfacial bonding strength increased most aftertempering at 350℃for 45 min.The microstructure of the interface was observed using a digital microscope.The resultsshowed that the dispersed oxides on the interface were basically eliminated by using the scheme of tempering at 350 cand holding for 45 min.The reasons for the change in mechanical properties were explained from the point of theinterfacial microstructure.Scanning electron microscopy was used to analyze the micro-morphology of the tensile fracture.lt was observed that after tempering at 350℃and holding for 45 min,the dimple holes became larger and deeper,and thestructure of fracture became more uniform and stable.From the point of the tensile fracture morphology.the reasons for thechange in mcchanical propcrties wcrc explained as well.

Influence of process parameters on interracial tensile strength of crosswedge rolling of 42CrMo/Q235 laminated shafts

Through rolling experiments and interfacial tensile strength tests of cross-wedge rolled laminated shafts of 42CrMo/Q235 composites, the influence of process parameters, including forming angle, spreading angle, area reduction, rolling temperature and core material diameter on the interfacial shear strength was analyzed. The results show that the sequence of process parameters in order of greatest influence on interfacial tensile strength was rolling temperature, area reduction, core material diameter, forming angle and spreading angle. At the interface of the combined materials, tensile strength decreased as forming angle and spreading angle increased, whereas the tensile strength first increased and then decreased as area reduction, rolling temperature and core material diameter increased.