扭杆弹簧的早期断裂和预防措施

45Cr NiMoVA钢扭杆弹簧发生早期断裂。通过断口分析、化学成分、金相检验和硬度检测分析了扭杆弹簧断裂的原因。结果表明,扭杆弹簧的花键齿表面存在脱碳现象,使断裂韧度和疲劳强度降低,在交变载荷作用下,在花键齿根萌生疲劳源,最终导致扭杆弹簧早期疲劳断裂。预防扭杆弹簧早期断裂的措施是避免扭杆花键齿表面脱碳和适当提高淬火后的回火温度。

Premature Break of Torsion Rod Spring and Precautions

The torsion rod spring of 45 CrNiMoVA steel broke in early stage.The causes for the torsion rod spring break was analyzed by means of fracture test,chemical composition analysis,metallographic examination and hardness test.The results show that decarburization exist in spline tooth surface of the torsion rod spring,resulting in decrease in the fracture toughness and fatigue strength,initiation of fatigue source at the spline tooth root,and the final torsion rod spring break under the action of alternating load.The measures preventing the torsion rod spring from premature breaking are to keep the torsion rod spline tooth surface from decarburization and to increase the temperature of tempering subsequent to hardening to a certain extent.