S. Palaniya Pillai, P. Manjunath, N. Ramamurthy, Tube Investments of India, Chennai, India
Induction heat treatment is emerging as a potential thermal process for heat treating ferrous and non-ferrous materials. It offers flexibility in manufacturing and quality improvements in the components. Welded steel tubes offer wider applications in the area of automotive sectors in terms of weight reduction opportunities. Specifically, high strength steel tubes (DP and martensitic steel tubes) provide excellent avenues for strength to weight ratio applications. These high strength steel tubes can be produced by induction heat treatment. With advent of induction heat treatment, it is possible to produce high strength welded steel tubes (DP and martensitic steel tubes) in the range of 700 – 1500 MPa tensile strength. In the present investigation, three popular steel grades are taken SAE1012M, SAE1019M , SAE1026 and SAE1541. Induction hardening and tempering are carried out. Further, hardening and tempering temperatures are varied to study its effect on mechanical and fatigue properties. Scanning electron microscopic work is carried out to understand the submicroscopic behavior in the induction tempered samples. Structure property correlations are made to link between microstructure, mechanical properties and fatigue values. It is observed that induction tempered tube has shown better fatigue values compared to conventional thermal process. Torsional fatigue and bending fatigue are carried out to quantify the effect of induction tempering on endurance limit in the components. A comprehensive analysis on automotive components benefit out of this process has been discussed in this paper.
