Intensification of the Transition of Retained Austenite to Martensite Effected by Changing the Stress State in Trip Steel Wires / Intensyfikacja Przemiany Austenitu Szczątkowego W Martenzyt Pod Wpływem Zmiany Stanu Naprężenia W Drutach Ze Stali Typu Tr Ip

Abstract

Change in the stress state is one of the factors that determined the transition of retained austenite to martensite. It has been proved that in products made from wires of a TRIP structure, which is characterized by a high retained austenite content, loading them with varying in sign cyclic stresses of magnitudes lower than yield strength (R0.2) results in intensive transition of the retained austenite to martensite. The paper presents a comparative analysis of investigation results concerning the determination of the quantity of retained austenite in the structure of wire for two TRIP steel grades with varying carbon content after they have been loaded with varying in sing cyclic stresses of a magnitude smaller than R0.2 under rotating bending conditions. The investigation carried out has determined whether and, if so, to what extent the loading of wire with cyclic external stresses of magnitudes lower than R0.2 may influence the quantity of transformed retained austenite and thus the mechanical properties of the products.

Keywords

• TRIP steel
• wire drawing
• retained austenite