Phase transformation residual stress in granular structure

The phase transformation residual stress caused by the volume expansion during transformation from austenite to marterisite was calculated by finite element method based on the assumption of specific distribution and shape of martensite island. The effect of residual stress on the macroscopic strain-stress relationship is also discussed. The results show that tension hydrostatic stress exists in ferrite matrix, compression stress exists in martensite island. The residual stress increases with the increase of the martensite amount, ferrite yield strength and tangent modulus. There is a critical martensite amount for ferrite yielding entirely. The residual stress contributes to the continuous yielding of air cooling granular structure steel but effects the yield strength of granular structure little.