本研究探討鋯合金R60702 2mm板材電漿電弧銲接後其機械性質之研究。藉由拉伸試驗檢驗母材與銲接過後伸長量、施力、工程應力與工程應變之差異，並求出其真實應力與真實應變數值。使用維氏硬度計量測母材、熱影響區與銲道之微硬度變化，並利用光學顯微鏡觀察上述區域間之金相組織變化。電子顯微鏡觀察拉伸試片之破斷面形態。
根據實驗結果，所有拉伸試片均斷於母材，顯示銲接熔融區結合強度高於母材。此外，鋯合金R60702母材之抗拉強度、降伏強度、延伸率和硬度為497.95MPa、322.10 MPa、38.40％與161HV。經銲接後抗拉強度與伸長率略降至484.22 MPa與24.40％，然而銲接後抗拉強度已達原母材90%顯示銲接品質良好。金相觀察發現熔融區中心處產生樹枝狀組織導致該區維氏硬度值較熔融區的平均低；銲冠處則產生籃織狀組織，為冷卻較快所造成，故此處具有最大之維氏硬度值。最後，利用電子顯微鏡觀測拉伸試片銲接處破斷面，具有韌窩狀組織屬延性破壞。

The purpose of this study is to investigate the plasma arc welding properties of the zircaloy R60702 thin 2mm by using the tensile test（including force, elongation, engineering stress and engineering strain）, the micro-hardness, the optical microscopy（base metal, hot affect zone and fusion zone）and scanning electron microscopy（ductile or brittle fracture）.
Based on the experimental results, all of the tensile specimens ruptured in the base metal. Bonding strength of fusion zone was higher than that of base metal. In addition, the tensile strength, yield strength, elongation and hardness of the zircaloy R60702 sheet before welding was 497.95 MPa, 322.10 MPa, 38.40%, Hv161, respectively. After welding, the tensile strength and elongation of weld were 484.22 MPa and 24.40%, respectively. The tensile strength of the welding region was about 90% of the base metal. Thus, the yielding strength will be higher than base metal, while the percentage elongation will be lower than base metal. From the microstructure observation, the surface of fusion zone was all columnar dendritic. The center of fusion zone tends to basket weave. The fracture surface of tensile test specimens has the feature of dimple.

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