Reason of destruction side frame of the trolley

Abstract

The metallographic and fractographic analysis methods were used to study the influence of the cast metal quality on the causes of the destruction of a railway carriage under high dynamic and cyclic loads. As a result of study structure fracture surface of the side frame freight car truck, the detected elements indicate simultaneous presence of fatigue and static fracture. The focus of nucleation fatigue crack was a surface defect of casting origin such as a blockage. Volumes with a concentrated arrangement of gas bubbles and non-metallic inclusions of various nature was found in the individual elements of the side frame. As a result of acceleration of moving fatigue crack, there are achievements of continuous decrease of construction of strength side frame. The meeting of the fatigue crack with volumes metal with an increased concentration of gas bubbles and non-metallic inclusions accelerated the transition to the phase of static fracture. Improving the operational safety of the side frame is possible by improving the foundry technology of its manufacture and changing the regulatory documentation to limit non-metallic inclusions and pores in the metal.

Keywords

• crack
• fatigue
• fracture
• non-metallic inclusions
• pores.