工业生产中Zr702锆卷MIG焊接工艺

MIG welding process of Zr702 zirconium coil in industrial production

应用光学显微镜(OM)、扫描电镜(SEM)和能谱仪(EDS)等技术对不同焊接工艺条件下的Zr702卷MIG焊接接头的组织及性能进行了研究和分析。结果表明,工业纯锆Zr702在MIG焊接过程中高温下的焊缝熔池和热影响区容易受到空气污染,吸收空气中大量的氧气,氧原子以间隙原子形式固溶在锆基体中,造成晶格畸变,内应力变大,恶化焊接接头性能;采用尾部拖罩保护,可以有效保护焊缝免受空气污染,得到力学性能良好的焊接接头;被空气污染的焊缝颜色为灰黑色,而惰性气体保护良好的焊缝颜色为银白色;在工业纯锆Zr702焊接过程中,热影响区会产生马氏体相变,小电弧电压、快焊接速度可以得到晶粒尺寸较小的板条马氏体;在工业纯锆Zr702焊接时,采用尾部拖罩保护、在保证焊缝成形的基础上采用小电弧电压、快焊接速度可以得到力学性能良好的焊接接头。

Microstructure and properties of Zr702 coil MIG welded joints under different welding conditions were studied and analyzed by optical microscope(OM),scanning electron microscope(SEM)and energy dispersive spectrometer(EDS).The results showed that weld pool and heat affected zone of industrial pure zirconium Zr702 at high temperature in MIG welding process were prone to air pollution,absorbed a large amount of oxygen in the air,oxygen atoms were solubilized in the zirconium matrix in the form of interstitial atoms,which resulted in lattice distortion,greater internal stress and deteriorating performance of welded joints.Rear trailing cover was adopted to effectively protect weld from air pollution and obtain welded joints with good mechanical properties.Welds polluted by air were gray black,while welds with good inert gas protection were silver white.During welding process of industrial pure zirconium Zr702,martensite transformation would occur in heat affected zone.Small arc voltage and fast welding speed could produce lath martensite with finer grain size.When industrial pure zirconium Zr702 was welded with protection of rear trailing cover,and on the basis of ensuring formation of weld,welded joints with good mechanical properties could be obtained by small arc voltage and fast welding speed.