置氢0.12wt%H对Ti-0.3Mo-0.8Ni氩弧焊接接头组织演变的影响（英文）

Effect of 0.12wt% Hydrogen Addition on Microstructural Evolution of Ti-0.3Mo-0.8Ni Alloy Argon-arc Welded Joints

基于光学显微镜、X射线衍射仪和透射电子显微镜分析,研究了置氢0.12 wt%H对Ti-0.3Mo-0.8Ni氩弧焊接接头微观组织演变影响,揭示了氢元素对无损焊接接头组织特性影响规律。结果表明:氢化物析出促使焊接接头初始组织发生变化,置氢量增加有助于焊接接头微观组织中β相析出。薄片状的面心立方δ氢化物均匀分布在置氢量为0.12 wt%H的焊接接头中,且仅能从层片状α相中析出,但无法从转变β相中析出。δ氢化物的析出与αH相分解反应:αH→α(贫氢区)+δ(富氢区)相关,富氢区最终转变为δ氢化物.置氢焊接接头组织中的位错分布不均匀,δ氢化物析出产生的应力场引起的晶格畸变直接导致了析出δ氢化物附近有相对密度高的位错分布。

The effects of hydrogen addition(0.12 wt% H) on microstructural evolution in Ti-0.3 Mo-0.8 Ni alloy argon-arc welded joints have been investigated using optical microscope(OM), X-ray diffraction(XRD) and transmission electron microscopy(TEM) to reveal the influence of hydrogen on the characteristics of defect-free titanium alloy welded joints. The results show that hydride precipitation changes the initial microstructure of the welded joints. The increase of hydrogen content is favorable for the β phase precipitation. Face centered cubic δ hydride is evenly distributed in the hydrogenated 0.12 wt% H welded joints. The lamellar δ hydride could only precipitate from the lamellae α, and not from the transformed β phase. Formation of δ hydride is associated with the result of αH phase separation reaction: αH→α(H lean region) + δ(H rich region), and H rich regions finally transform to the δ phase. The dislocation distribution is heterogeneous and there is a relatively high density of dislocations in the vicinity of the precipitated δ hydride, which are caused by the lattice distortion due to the stress field generated by the hydride precipitation.