Inconel718合金多层夹芯筒结构LBW/SPF技术研究

Study on LBW/SPF Technology of Multi-sheet Cylinder Sandwich Structure for Inconel718 Superalloy

研究了超细晶Inconel718合金激光对接板高温塑性及多层夹芯筒结构的LBW/SPF成形技术。结果表明:垂直焊缝拉伸时最大延伸率发生在温度为950℃、应变速率为3.1×10-4s-1条件下,为400.6%,平行焊缝拉伸时最大延伸率发生在温度为965℃,应变速率为6.2×10-4s-1条件下,为164.0%。对接板在950～980℃相对胀形高度均高于1.0。通过设计直径可变的卡具以及采取点焊加固等措施,解决了多层夹芯结构的激光焊接难题。激光穿透焊参数:功率1 200 W,焊速1 200 mm/min,离焦量-1 mm,保护气体流量0.6 L/min,超塑成形参数:温度Tf=965℃,压力Pf=4.2 MPa,时间tf=130 min。采用LBW/SPF技术制造的多层夹心筒结构具有外观形状好、壁厚分布均匀、内部结构对称度高等优点。

The high temperature plasticity of the laser butt welding plate and LBW/SPF technology for Inconel718 superalloy with ultrafine grain were investigated. The results showed that when the tensile direction is vertical to laser welding seam, the maximum elonga- tion is 400.6% at temperature of 950 ℃ with initial strain rate of 3.1 ×10 -4 s -1. When the tensile direction is parallel to laser welding seam, the maximum elongation is 164.0% at temperature of 965 ℃ with initial strain rate of 6.2 × 10 -4 s -1. At the temperature of 950 ~ 980 ℃, the laser butt welding plate has good plasticity in free bulging state. The relative bulging height is higher than 1. 0. The laser welding problem of multi-sheet cylinder sandwich structure is settled through clamp apparatus which has internal stay of diametral varia- tion. The laser penetration welding parameters are the power of 1 200 W, welding speed of 1 200 mm/min, defocusing amount of - 1 mm, shield gas flow rate of 0.6 L/min. The parameters for superplastic forming are the temperature of 965 ℃, pressure of 4.2 MPa, time of 130 min. The multi-sheet cylinder sandwich structure by LBW/SPF composite technology has good shape, uniform wall thickness distribution, the high symmetry of internal structure.