塑性变形T8碳素钢中渗碳体相的残余应力

X-ray Estimation of Residual Stress Carbide in Carbon Steel T8

运用X射线残余应力测量法分析了含有球状渗碳体的碳素钢在拉伸塑性变形后铁素体相及渗碳体相的残余应力情况。结果表明:在经过拉伸塑性变形后,铁素体相呈现残余压应力状态,而渗碳体相呈现残余拉应力状态;当施加的塑性应变在边界应变点之前,渗碳体的残余应力随应变值的增加而增大,而在边界应变点之后,残余应力呈下降趋势。观察发现渗碳体颗粒内部的断裂及渗碳体与铁素体结合边界部分的分离是引起渗碳体残余应力下降的原因。为了更好地理解渗碳体相和铁素体相之间的相互作用,在Eshelby/Mori-Tanaka模型的基础上分析了两相各自的塑性应变及两相间的塑性应变失配。

Residual stresses of ferrite and cementite phases in globular and lamellar structure carbon steel T8 with tensile plastic deformations were investigated with XRD. For globular structure specimens, the X-ray stress measurement of cementite was carried out, the compressive and the tensile residual stresses in cementite were observed in ferrite. The residual stress in cementite increased with exerted plastic strains till the border strain point and decreased thereafter. The SEM analysis indicated that the crack in the cementite particle and the crack at the boundary between cementite particle and matrix might low the residual stresses in cementite phase. In order to well understand the interaction between cementite and matrix, the plastic strains of two phases and the misfit of plastic strains between them were analyzed based on the Eshelby/Mori-Tanaka model.