The Influence of Brazing Clearance on Joint Strength of Nickel Based Amorphous and Crystalline Brazing Filler Metals

The systematic researches on the characteristics of brazed joints vs.brazing clearance for 1Cr18Ni9Ti stainless steel vacuum brazed with amorphous and crystalline Nickel-based(Ni82.5Cr7Si4.5B3Fe3) brazing filler metals at different brazing variables have been made,and the relationship between brazement structure pattern and brazed joint has also been investigated.The experimental results indicate that there exists the strength platformin the curves of brazed joint changing with brazing clearance,the two characteristic brazing clearances corresponding to the strength platformin the curves are called the minimal usable brazing clearance Wmin and the maximal usable brazing clearance Wmax.From the point of obtaining good joint filling quality and formation,the brazing clearance should not be less than 0.01 milimeter;and from the view of making brazement free from brittle compound phases and getting high joint strength,the brazing clearance can not be larger than the critical clearance WcB.There are very small changes on brazed joints when the brazing clearance changes within the two characteristic clearances.From the experimental results,it can been found that Wmax increases and Wmin remains stable when brazing temperature rises or brazing time is added.