Scar analysis of 55SiCrA spring steel oil quenching tempered steel wire

Sicra spring steel is mainly used in manufacturing suspension spring of automobile suspension system. It is an important damping elastic element, which requires high elastic limit and relaxation resistance under cyclic alternating stress.At the same time, in the process of use, the stress on the cross section of the spring element increases gradually along the radial direction from the center to the edge.The surface of spring steel will be scarred, which will seriously reduce the fatigue life of the spring.

The production process of 55SiCrA spring steel oil quenching tempered steel wire is as follows :110t electric furnace → LF furnace refining → RH vacuum degassing →large round billet →continuous casting →once heating billet rolling → sixth continuous rolling →150mmX 150mm billet →grinding →secondary heating high → speed wire controlled rolling and controlled cooling →wire (O14mm) →phosphorus removal → drawing (O12.5 mm) to induction heating →vacuum oil quenching. Induction tempering to eddy current flaw detection, winding, packing .The roll of steel wire after eddy current flaw detection, inspection device, alarm, the alarm of wire sampling inspection, found that the surface scarring. To do this. For steel rolling and pure silk processing situation to conduct a comprehensive analysis in various processes, and the defect sample, macro, metallographic examination, scanning electron microscopy (sem). Energy spectrum and microhardness analysis. Through the analysis, find out the causes of scarring, and in order to take corresponding measures to avoid such incidents from happening again.

By means of macroscopical morphology, metallographic examination, scanning electron microscope, energy spectrum and microhardness analysis, the causes of scarring on the surface of 55SiCrA spring steel oil-quenched tempered steel wire were found out.The main reason is that customers in the tempering induction heating process of electric spark hit on the steel wire scar, customers through the process adjustment, can effectively avoid the scar defects.