CZ锆合金与316L不锈钢真空钎焊接头的界面组织及力学性能

Interfacial Microstructure and Mechanical Properties of Vacuum Brazing Joint between CZ Zircaloy and 316L Stainless Steel

采用BAg72Cu银基钎料对CZ锆合金与316L不锈钢进行真空钎焊,研究了其界面微观组织及力学性能。结果表明,经真空钎焊后其接头界面组织连续且致密,钎料与两侧母材均实现了良好的冶金结合。钎焊温度为800、820、850℃时,从不锈钢侧到锆侧的接头组织依次为Fe(Cr,Zr)_(2)、Zr(Fe,Cr)_(2)、(Zr,Cu)、Zr_(2)Ag、α-Zr+Zr_(2)Cu+Zr_(2)Ag。钎焊温度为880℃时,由于铁元素大量扩散,焊缝中生成了Zr3Fe相。820℃钎焊时接头的室温抗剪强度最高,为125 MPa。银铜钎料的加入使接头显著硬化,近不锈钢侧的扩散层硬度值最大,约为725 HV。所有钎焊工艺下,剪切断裂都发生在母材锆合金与钎料之间的界面,断口形貌为典型的河流状花纹和台阶,为脆性解理断裂。

Vacuum brazing between CZ zircaloy and 316L stainless steel was carried out by using BAg72Cu filler metal,and the interface microstructure and mechanical properties were studied.The results show that the interface of the joint is continuous and compact after vacuum brazing,and good metallurgical bonding is achieved between the filler metal and the base metals.At the brazing temperature of 800,820 and 850℃,the microstructure of the joints from stainless steel side to zircaloy side is Fe(Cr,Zr)_(2),Zr(Fe,Cr)_(2),(Zr,Cu),Zr_(2)Ag,α-Zr+Zr_(2)Cu+Zr_(2)Ag in turn.When the brazing temperature is 880℃,the Zr3Fe phase is formed in the joint due to large diffusion of Fe.When it is brazed at 820℃,the shear strength of the joint at room temperature is the highest,which is 125 MPa.The joint is hardened obviously after addition of silver-copper solder,and the hardness of the diffusion layer near the stainless steel side is the highest,about 725 HV.Under all brazing processes,shear fracture occurs at the interface between the base metal zirconium alloy and the solder.The shear fracture morphology is typical river patterns and steps,which is brittle cleavage fracture.