Transformation-induced plasticity of expandable tubulars materials

A new concept on strengthening-plasticity is presented in this paper, along with the design rules of the alloys with high expandable performance. The plasticity of expandable alloys induced by the γ→ɛ martensitic transformation, can be obviously improved. In order to enhance transformation-induced plasticity, alloys with low stacking-fault energy and high starting temperature of ɛ martensite Ms(ɛ) should be looked for. Therefore, a formula for the calculation of Ms(ɛ) of Fe-based alloys is also given in this paper in order to facilitate the design of expandable tubular materials.