Abstract
The mechanical properties and microstructures of a low carbon steel by various heat treatments were investigated by the tensile test with cyclic loading and unloading. The specimens as received and as annealed at the low temperature show the plastic deformation. However, the specimens as quenched show pseudoelasticity behaviors, i.e. the strain recover when the stress reached zero during unloading. The specimen as tempered after quenching with d=9.0mm first deformed plastically and then pseudo-elastically and the specimen with d=12.5mm show pseudoelastic deformation on all loading cycles. The microstructures of the specimens were observed by optical microscopy.
