IMPROVEMENT OF JOINT EFFICIENCY FOR FUNCTIONAL MATERIALS

采用熔焊和固相结合的方法焊接了多种高性能的铁、有色金属材料，并对接头的微观组织进行了研究，以揭示影响接头效率的因素，并提出提高接头效率的措施。所得结果总结如下：1。对SUS304、SUS316和SUS329JI三种不锈钢的熔焊进行了系统的研究，重点研究了焊接气氛和热循环对焊接性能和接头效率的影响。气氛方面，确定了在高达6 MPa的高压气氛下实现良好可焊性的焊接参数，并考察了焊缝金属的断裂韧性随氧气分压的变化规律。焊缝热循环对P的晶界偏析有较强的影响，显著加速了P的晶间应力腐蚀开裂。2. 研究了Ti-6Al-4V合金焊接热影响区的组织和结构，以解释焊接热循环对合金力学性能和氢致开裂的影响。3. 为了将扩散结合技术应用于Al/Al_2O_3和Al/SiC复合材料，系统地研究了表面处理和中间金属对扩散结合强度的影响。发现电抛光和中间金属对铝镁铜合金的表面处理可以提高纤维的结合强度，并讨论了中间金属对纤维润湿的影响。4. 以Cu-W烧结合金与铜的摩擦焊接为研究对象，研究了W含量对焊缝行为和微观组织的影响，以解释接头效率的控制因素及其机理。5. 对具有形状记忆效应的NiTi合金进行了不同气氛下的熔焊。虽然在惰性气氛下获得了良好的焊珠，但焊缝的显微组织与母材的显微组织有很大的不同，表明接头的形状记忆效应明显减弱。6. 研究了马氏体、贝氏体和铁素体组织对HT80钢应力释放开裂的影响。少

A wide variety of ferrous and non-ferrous materials of high functions have been bonded by the fusion welding and solid state bonding, and the microstructure of joints have been investigated in order to reveal the controlling factor of the joint efficiency and to develop the measure for its improvement. Results obtained are summarized as follows: 1. The fusion welding of stainless steels SUS304, SUS316 and SUS329JI has been systematically investigated with particular reference to the effects of welding atmosphere and heat cycle on the weldability and joint efficiency. As to the atmosphere, the welding parameters for realizing good weldability were determined in high pressure atmosphere up to 6 MPa, and the fracture toughness of weld metal was examined as a function of the partial pressure of oxygen. The weld heat cycle was found to have strong effects on the grain boundary segregation of P, which accelerated the intergranular stress corrosion cracking significantly. 2. The microstructur … More e of the weld heat affected zone of Ti-6Al-4V alloy was investigated to interpret the effects of the weld heat cycle on the mechanical properties and hydrogen induced cracking. 3. In order to apply the diffusion bonding to Al/Al_2O_3 and Al/SiC composites, the effects of surface treatments and intermediate metals on the bond strength have been systematically investigated. The surface treatment of electropolishing and the iritermediale metal of Al-Mg-Cu alloy were found to improve the bond strength, and their effects were discussed in relation to the wetting of the fiber by the intermediate metal. 4. For the friction welding of the Cu-W sintered alloy to copper, the effects of W content on the behavior of welds and the microstructure have been examined to explain controlling factors of the joint efficiency and its mechanism. 5. The fusion welding of NiTi alloy with shape memory effect have been carried out in various atmospheres. Though sound weld beads were obtained in inert atmospheres, the microstructure of the weld obtained was quite different from that of the base metal, suggesting that the ghape memory effect of the joint was significantly degraded. 6. The effects of martenstic, bainitic and ferritic microstructures on the stress relief cracking has been investigated for HT80 steel. Less