摘要
液相扩散焊 ( TLP)焊管方法以其特有的高自动化程度、高生产率、高性能、低变形、无焊接烟尘与飞溅等优点已引起了日本学术界与产业界的极大研发兴趣。重点介绍了日本新日铁公司的研究人员采用 α中子射线照射法对碳素钢液相扩散焊中降熔元素 B的扩散行为及存在形态的研究成果。研究结果指出 ,中间层内的降熔元素 B扩散入碳钢母材后 ,在冷却过程中 B在晶界聚集 ,以 Fe2 3( C,B) 6 化合物方式析出 ;在晶界周边则形成贫 B层 ,其结果是晶界近旁的淬硬性大幅度降低 ;接合部组织由晶界铁素体及晶内上贝氏体组成。在保温 60 0 s时 ,扩散距离达 2 mm,并求得 B在 1 4 73 K温度下的扩散系数为 1 .1× 1 0 - 9m2
The new pipe welding process by transient liquid phase (TLP) diffusion bonding has the following advantages,such as high automation,high efficiency,high property,a little deformation,no welding splash and smoke,so,the mechanism and application of the new TLP pipe welding process to plain carbon steel pipe have been investigated by some researcher in famous university and company in Japan.In this review, the distribution and diffusion behavior of boron in the transient liquid phase (TLP) bonded joint of carbon steel which indicated out by research scientists in Nippon Steel Co.(NSC) using α-autoradiographs are introduced primarily.There experimental results are as follows.Boron congregated at grain boundary,and boron separated at grain boundary with compoundof Fe23(C,B)6.On the other hand,poor boron layer appeared around grain boundary,so the brittleness of region around grain boundary can be greatly decreased.Themicrostructure of bonded zone consist of upper bainite and grain boundary ferrite.When holding time is 600S at 1 473 K,the diffusion distance of boron into base metal is 2mm,and the diffusion coefficient of boron at 1 473 K is derived to be 1.1×10 -9(m 2/s).
出处
《焊管》
2003年第5期56-60,62,共5页
Welded Pipe and Tube
