The Microstructures And Performances Of 12Cr1MoV Tlp Bonding Joints With Different Bonding Parameters

Pearlitic heat-resistant steel 12Cr1MoV were bonded by transient liquid phase diffusion bonding with different process parameters, the bonded results were texted include the tensile test, metallographic observation, scanning electron distribution of elements and fracture analysis, the research results of their joint organization and performance showed that:12Cr1MoV joint can be achieved with the TLP bonding methods, the joints performance can be close to the performance of the base material, when the bonding temperature: 1200℃, bonding pressure: 4MPa, and holding time: 3min, the joint performance can reach the base material properties.The bonding temperature have a great influence on the bonding joints properties and the TLP bonding process, with the bonding temperature increased from 1150℃to 1170℃, 1200℃, the organization and performance of TLP bonding 12Cr1MoV joint had been improved, the spread of the melt pointing depressant element getting better and better, however, when the bonding temperature increased to 1220℃, the lower joint tensile strength was obtained. Studies have shown that: there is a critical bonding temperature. During the TLP bonding process, for a given interlayer alloy and base metal, the width of the weld is determined by the bonding temperature. The bonding temperature plays a dual role: the increasing temperature can enhance the diffusion coefficient of the melt pointing depressant element, but at the same time, increasing the liquid maximum width, reduces the concentration gradient of the interface elements which are not conducive to the completion of isothermal solidification.The bonding pressure also have a great impact on the TLP process and the joint performance, as the pressure increased from 3MPa, to 4MPa, 5MPa, the organization and properties of bonded joints have been improved and enhanced. Research showed that: during the transient liquid phase diffusion bonding process, there exists a critical value about the choice of the bonding pressure. In the bonding process, the pressure applied can reduce the maximum width of the liquid, at the same time; reduce the contents of the melt pointing depressant element, so the time required of the completion of isothermal solidification can be reduced.Holding time is also a key factor to determine the TLP bonding joint microstructures and performance, with the holding time increased from 1min to 4min, the joints mechanical properties and microstructure have been improved and the connection interface become better and better. From the study follow conclusions can be gotten: there is an optimum of the choice about the holding time during the TLP connection process. At the same time, the change of the holding time can not change the width of the weld, which only can improve the connectivity interface conditions. Holding time and the bonding temperature affects the grain size of the welded joints, which determine the joint microstructures and performances so must be controlled during the bonding process.