中文摘要：

研究了2 mm厚的AZ31B镁合金薄板在TIG-MIG双弧堆焊条件下的工艺特点,利用金相显微镜、扫描电镜等对焊接接头显微组织、焊缝相成分等进行了分析。结果表明,焊接接头主要由母材、热影响区、焊缝区组成。在热影响区和焊缝区之间有较明显的熔合区,该区域由熔池边界半熔化状态的部分冷却而成。由于热循环和焊接冶金作用有大量的析出物（Mg17Al12）,因此可以推断此处力学性能较差。焊缝区组织较细,有多种金属间化合物析出。

英文摘要：

The technical characteristics of TIG-MIG double arc surfacing of AZ3 I B alloy plate with the thickness of 2 mm were discussed. The metalloscope and scanning electron microscopy were used to investigate the microstructure and phase composition. The results show that the welded joints constitute of base material,heat affected zone （HAZ）and weld zone.A large number of precipitates （Mg~TAl12）exist in the significant fusion zone which appears between HAZ and weld zone. In weld zone, the fine grains can be obtained, and several kinds ofintermetallic compounds precipate.