超高强度300M钢电子束深缝焊接力学性能及破坏机理研究

超高强度300M钢具有优异的力学性能,广泛应用于飞机起落架。通过静力拉伸、三点弯曲及动态Charpy冲击试验,揭示300M钢电子束深缝焊接的力学性能及破坏机理;对试验后的典型试样进行断口宏观与微观分析,并采用场发射扫描电镜(SEM)对断口形貌进行观察、分析。结果表明:母材与焊接件都出现明显的拉伸塑性段,二者的刚度和强度相差不大,但是焊接件的断裂应变较母材小,焊接件焊缝的韧性略低于母材;焊接件弯曲强度与母材相当,但是破坏时的弯曲变形较母材也有所下降,焊接件的延性较差;在冲击试验中焊接件吸收能量与断裂韧性均低于母材,冲击韧度降低。

Study on Mechanical Properties and Failure Mechanism of Deep Seam Electron Beam Welding of Ultra-high Strength 300M Steel

The ultra-high strength 300M steel is applied in aircraft landing gear. The tests of static tensile strength, three-point bending properties and Charpy impact properties were conducted. It reveals the mechanical properties and failure mechanism of electron beam deep seam welding of 300M steel. Macroscopic and microscopic analysis of typical specimens fracture after testing and fractography of weldment fracture surface have been investigated by SEM (Scanning Electron Microscope). Results indicate that both parent metal and weldment appear obvious tension plastic behavior, and there is little difference between stiffness and strength. However, the fracture strain and toughness of weldments becomes weaker compared with the parent metal. The bending strength of weldments is slightly lower than that of the parent metal, and the bending deformation and ductility decline. In Charpy impact test, both absorbed energy and fracture toughness of weldments are lower than parent metal. Thus the impact toughness of weldments decreases.