低活化钢双壁管的热等静压扩散连接

双壁管可控制裂纹扩展路径，防止裂纹沿管径向扩展，显著提高了管的使用安全性，被认为是聚变堆包层增殖区冷却管的理想选择.针对双壁管复合焊接难题，从钢/铜/钢和钢/镍/钢平板复合结构开展了工艺优化试验. 结果表明，热等静压温度高于1 100 ℃时，钢/铜/钢复合界面处发生晶界扩散，焊接接头室温抗拉强度达601 MPa，界面纳米压痕硬度1.37 GPa；钢/镍/钢复合界面处产生了更宽的元素固溶扩散，室温抗拉强度可达630 MPa，界面处纳米压痕硬度2.05 GPa.采用优化后的热等静压参数制备了连接质量良好的多折弯双壁冷却管原型件.

HIP diffusion bonding of reduced activation steel double wall tube

The double-wall tube can control the crack propagation path and prevent the crack from spreading along the tube diameter, which significantly improves the safety of the tube. Therefore, it is the ideal choice for the cooling tube in the breeding blanket zone of fusion reactor. The process optimization experiments of steel/copper/steel and steel/nickel/steel flat composite structures were carried out to solve the problem of double-wall tube. The results show that grain boundary diffusion occurs at steel/copper/steel composite interface when the hot isostatic pressing temperature is higher than 1 100 ℃. The room temperature tensile strength of the welded joint reaches 601 MPa and the interface nanoindentation hardness is 1.37 GPa. Wider solid solution diffusion of elements occurs at the steel/nickel/steel composite interface, the tensile strength at room temperature can reach 630 MPa, and the nanoindentation hardness at the interface is 2.05 GPa. Prototypes of multi-bending double-wall cooling pipes with good connection quality were achieved by using optimized hot isostatic pressing parameters.