板翅结构钎焊残余应力与热变形的有限元分析

Finite element analysis of residual stresses and thermal deformation for brazing plate-fin structure

对微小尺寸的镍基钎焊不锈钢板翅结构在真空钎焊过程中产生的残余应力分布与热变形状况进行研究分析。采用有限元方法对三层结构的钎焊过程进行了热—力分析,分析考虑真空钎焊的加热特点同时考虑板翅材料和镍基钎料与温度相关的材料特性,得到了钎焊过程中结构的温度变化规律以及钎焊后的残余应力分布和热变形特征。结果表明,隔板与翅片具有不同的热变形特征,板翅钎焊接头钎角处应力状况复杂,易萌生裂纹导致板翅结构的失效,需要选择合适的钎焊时间以得到较好的钎焊接头。

This contribution focuses on the analysis of residual stress and thermal deformation of microminiaturized nickel base brazing stainless steel plate-fin structure after vacuum brazing.A finite element method is utilized to conduct the thermal-mechanical analysis for brazing such three layers structure,and the actual heating history of vacuum brazing and temperature-dependent material properties of plate-fin and filler metal are considered. The thermal cycles during brazing,thermal distortion and residual stress after brazing are reported.The results show that plates and fins have different deformation features,and complex stress state appears in the region of joint fillets which may induce the crack generation and propagation of brazed joint and result in the structure failure in service.It is noteworthy to control appropriate brazing time to get preferable joints.