钢管表面脱碳层对钛-钢双金属管扩散复合界面的影响

Effect of Decarburized Surface Layer on Diffusion Compound Interface in Titanium-Steel Bimetallic Tube

研究了在异种金属热膨胀差引起的内压力作用下，钛管与低碳钢管扩散复合界面的成分、组织、结合强度及钢管表面脱碳层的影响．结果表明：通过内压扩散复合法可以使钛管与钢管之间实现冶金结合。在保温30min的条件下，750℃～800℃之间扩散退火时界面结合强度最高，且钢管表面脱碳与否对界面结合强度影响不大；碳原予向晶界扩散引起界面附近钢侧柱状晶区，铁原予向钛中扩散引起界面附近钛侧无晶界区与针状马氏体区，钢表面脱碳加速这一过程的进行．

Composition, microstructure and bond strength of Ti-steel tube compound interface were conducted to study inner stress caused by the difference of thermal expansion between two different metals, as well as the effect of decarburized layer on steel tube surface. Results showed that it is feasible to obtain a metallurgical bonding between Ti and steel tubes by inner-pressure technique, the bonding strength of the interface is maximumedby diffusion annealing between 750℃ -800℃ for 30 min ,and decarburation has little effect on the bonding strength of the interface. Columnar crystal areas are generated near the interface by carboatomic diffusing in to grain boundary ,and acicular martensitic areas are generated near the interface by Fe atoms diffusing to Ti, and decarburation on steel surface promotes the process.