Influences of different filler metals on electron beam welding of titanium alloy to stainless steel

Electron beam welding experiments of titanium alloy to stainless steel were carried out with different filler metals, such as Ni, V, and Cu. Microstructures of the joints were examined by optical microscopy, scanning electron microscopy and X-ray diffraction analysis. Mechanical properties of the joints were evaluated according to tensile strength and microhardness. As a result, influences of filler metals on microstructures and mechanical properties of electron beam welded titanium-stainless steel joints were discussed. The results showed that all the filler metals were helpful to restrain the Ti-Fe intermetallics. The welds with different filler metals were all characterized by solid solution and interfacial intermetallics. For each type of the filler metal, the type of solid solution and interfacial intermetallics depended on the metallurgical reactions between the filler metals and base metals. The interfacial intermetallics were Fe2Ti＋Ni3Ti＋NiTi2, TiFe, and Cu2Ti＋CuTi＋CuTi2 in the joints welded with Ni, V, and Cu filler metals, respectively. The tensile strengths of the joints were dependent on the hardness of the interfacial intermetallics. The joint welded with Ag filler metal had the highest tensile strength, which is about 310 MPa.

船用12型发动机连杆锻模设计及其锻造工艺验证实例

采用500 t双曲柄机械压力机和2500 t热模锻压力机生产船用12型发动机连杆。通过对该锻件的形状和结构的分析、阐述,对3个工步的制坯模具分别进行设计、分析和论证,并采用3工步分段制坯和模锻复合成形工艺进行小批量生产验证,得出预成形制坯模具的工步3的设计尤为关键,不但决定了终锻模膛的金属充填性能,而且对锻件的材料利用率有直接影响,还可以防止锻件产生折叠缺陷。通过对船用12型发动机连杆锻造工艺优化后,经过现场样件试制验证,得出船用12型发动机连杆的材料利用率为81.2%,合格率达99.4%,锻造工艺科学合理、切实可行。研究结论对小批量、多品种的锻件的研发试制具有重要的借鉴意义。