Effects of Brazing Process on Aging Performance of Double-Layer Welded Tube
Heat treatment tests of the steel sheets were carried out with multi-purpose annealing simulator for simulating brazing process of double-layer tube at different production speeds and brazing temperatures.Percentage yield point extension and aging index of the steel sheets brazed at different temperatures and different production speeds were measured by using tensile testing machine to study the effect of brazing temperature and tube production speed on the aging performance of double-layer welded tube.The results show that the higher the brazing temperature is,the lower the percentage yield point extension and the aging index are,the better the aging resistance of double-layer welded tube is.With the increase of the production speed,the percentage yield point extension and the aging index of the steel sheet increase,and the aging resistance becomes worse.This is due to the increase of the tube production speed,the shortening of the time of cooling age and the reduction of the content of the precipitated cementite.The aging index of the steel sheet before brazing is 10.6 MPa,it is 76.8-104.9 MPa after simualted brazing,and the aging resistance of the steel sheet obviously gets worse.
double-layer welded tubeaging indexbrazing process
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