Ni中间层对QBe2.5/钢激光点焊接头力学性能的影响

Effect of Ni interlayer on the mechanical properties of laser spot welded joints of QBe2.5/20~# steel

流量阀的执行机构常应用铍青铜/钢复合元件,本文采用0.05 mm纯Ni作为中间层对QBe2.5铍青铜薄片与20#钢异种金属激光点焊搭接接头力学性能进行优化.通过光学显微镜、拉剪试验、显微硬度计和能谱测试仪对比分析添加Ni与不添加Ni层时焊接接头的成形、力学性能以及元素分布.研究表明:与未加镍层接头相比,加镍中间层的焊缝熔深较小,且基本不出现下塌现象,加镍中间层比未加中间层的接头抗拉剪力提高了61.5%;加入镍中间层后的焊缝中Fe元素含量增加,而Cu元素含量降低,接头韧性提高;加镍中间层的接头焊缝硬度值沿焊点深度方向逐渐增大,而未加镍层的基本不变,且加镍层比未加镍层的接头界面显微硬度值低.镍中间层材料可以显著改善铍青铜/钢异种金属接头焊缝熔合比,提高接头的抗拉剪强度。

Flow valve precision often uses beryllium bronze/steel composite components. In this paper,to optimize the mechanical properties of the lap joints between QBe2.5 and 20#steel,0.05 mm-thick pure Ni is adopted as an interlayer for laser micro spot welding. The weld formation,mechanical properties and element distribution of the joints with and without Ni interlayer are contrastively analyzed through optical microscopy（OM）,tensile shear test,microhardness tester and energy spectrum analysis（EDS）. The results showed that the tensile shear of the joint with Ni interlayer increased by 61. 5%,weld penetration decreased and did not appear to collapse basically compared with the joint without Ni interlayer. Fe content inceresed,and Cu content decreased and enhanced the joint with Ni interlayer toughness. The microhardness value increased gradually along the depth direction of the weld after joining the Ni interlayer. However,the microhardness of joint without Ni interlayer was unchanged. And the average microhardness value at the joint interface was low obviously compared with the joint with Ni interlayer. Ni interlayer materials can significantly improve the weld fusion ratio and improve the shear strength,ductility and toughness of the joints.