真空室窗口领圈316L厚板电子束焊接接头不均匀性

Study on non-uniform properties of 316L thick plate joint using electron beam welding in port stub of vacuum vessel

关键词:  电子束焊接  扫描偏转  凝固模式

Key words:  electron beam welding  beam oscillation  solidification mode

摘要:

真空室是未来聚变工程实验堆的核心部件，其组件窗口领圈采用能一次焊透50 mm以上不锈钢且变形较小的电子束焊进行拼焊. 为了深入探索厚板焊接接头不均匀性，在焊接过程中应用扫描偏转并对50 mm厚的316L奥氏体不锈钢焊接接头厚度方向的微观组织和硬度进行分析. 结果表明，焊缝组织由奥氏体和铁素体组成，从焊缝中心线附近，上层到下层焊缝组织由粗大的板条状/骨架状铁素体依次变为更加紧密排列的骨架状铁素体和等轴晶状铁素体；带有扫描偏转的焊接接头在焊缝厚度方向更早出现等轴晶；扫描偏转能改善焊缝表面成形质量；焊缝显微硬度从上层到下层逐渐增加.

Abstract:

The vacuum vessel is the core component of the China future fusion engineering test reactor. Port stub is a part of vacuum vessel and it is welded by electron beam welding (EBW), which has capability to weld more than 50 mm thickness stainless steel by a single pass. In order to explore non-uniform properties of EB welded joint, beam oscillation was applied during the welding process and the microstructure and microhardness of 50 mm 316L austenitic stainless steel welded joint were analyzed. The results showed that the weld microstructure was composed of austenite and ferrite. From the upper layer near the center line of the weld to the lower layer, the microstructure changed from coarse lathy/skeletal ferrite to more close-packed skeletal ferrite and equiaxed gain. Welded joints with beam oscillation appeared equiaxed gain earlier in the weld thickness direction. Beam oscillation can improve the quality of the welds surface forming. The microhardness of the welds gradually increased from the upper layer to the lower layer.