Effect of grain size of primary α phase on bonding interface characteristic and mechanical property of press bonded Ti-6Al-4V alloy

The effect of grain size of primary α phase on the bonding interface characteristic and shear strength of bond was investigated in the press bonding of Ti-6Al-4V alloy. The quantitative results show that the average size of voids increases from 0.8 to 2.6 μm and the bonding ratio decreases from 90.9% to 77.8% with an increase in grain size of primary α phase from 8.2 to 16.4 μm. The shape of voids changes from the tiny round to the irregular strip. The highest shear strength of bond can be obtained in the Ti-6Al-4V alloy with a grain size of 8.2 μm. This is contributed to the higher ability of plastic flow and more short-paths for diffusion in the alloy with smaller grain size of primary α phase, which promote the void closure process and the formation of α/β grains across bonding interface.

Significance and interaction of bonding parameters with bonding ratio in press bonding of TC4 alloy

The variation of bonding ratio in the press bonding of TC4 alloy at temperatures from 850 to 900℃,pressures from 10 to 30 MPa,and time from 5 to 15 min was investigated.The bonding ratio increases with the increase of temperature,time and pressure.The maximum bonding ratio,i.e.98 %,can be obtained at 900℃,30 MPa and 15 min.The significance and interaction of bonding parameters with the bonding ratio were investigated.The results demonstrate that the effect of pressure on the bonding ratio is the most effective and the effect of temperature is secondary,while the effect of time is not very powerful.The interaction of bonding parameter on the bonding ratio exists but that is distinguishing in different bonding parameter ranges.It is concluded that increasing pressure can be considered as the primary method to increase the bonding ratio.

Mechanical Properties and Microstructure Evolution of AA1100 Aluminum Sheet Processed by Accumulative Press Bonding Process

Accumulative press bonding（APB） is a novel variant of severe plastic deformation processes,which is devised to produce materials with ultra-fine grain.In the present work,the mechanical properties and microstructural evolution of AA1100 alloy,which is produced by APB technique,were investigated.The study of the microstructure of AA1100 alloy was performed by optical microscopy.The results revealed that the grain size of the samples decreased to 950 nm after six passes of APB process.The yield strength of AA1100 alloy after six passes of the process increased up to 264 MPa,which is three times higher than that of the as-cast material（89 MPa）.After six passes,microhardness values of AA1100 alloy increased from 38 to 61 HV.Furthermore,the results showed that the behavior of variations in mechanical properties is in accordance with the microstructural changes and it can be justified by using the Hall-Patch equation.Moreover,the rise in the yield strength can be attributed to the reduction in the grain size leading to the strain hardening.

The Influence of Preheat Temperature of Steel Plate on Steel-mushy Cu-graphite Bonding

The pressing bonding of steel plate to QTi3.5-3.5 graphite slurry was conducted. Under the conditions of 530 ℃ for the preheat temperature of dies, 45% for the solid fraction of QTi3.5- 3.5 graphite slurry, 50 MPa for the pressure and 2 min for the pressing time, the relationship between the preheat temperature of steel plate and interfacial mechanical property of bonding plate was studied. The results show that when the preheat temperature of steel plate is lower titan 618 ℃ , the interfacial shear strength of bonding plate increases with the increasing of the preheat temperature of steel plate. When the preheat temperature of steel plate is higher than 618 ℃ , the interfacial shear strength decreases with the increasing of the preheat temperature of steel plate. When the preheat temperature of steel plate is 618 ℃ , the highest interfacial shear strength of bonding plate of 127.8 MPa can be got.

金属材料内部缺陷试块的热压扩散连接制备方法

针对空腔类缺陷的人工模拟无损检测试块的研制,提出热压扩散连接技术的制备方法。利用热压扩散连接方法,制备内部含有三种不同规格尺寸人工模拟缺陷的试块。分析结果表明,试块连接区域熔合较好,熔合线难以区分;基体组织未发生明显变化;试块内缺陷尺寸发生变化且呈现一定变化规律,变形率与缺陷边界夹角和缺陷所呈角度大小有关。试块宏观尺寸呈现一定的形变,无损检测及金相分析结果显示人工缺陷边界清晰,基体连接区域扩散连接充分且组织无有害缺陷。热压扩散连接法应用于空腔类缺陷的人工模拟无损检测试块的研制工作具有可行性。