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功能梯度硬质合金实现了高硬度与高强度的完美结合。然而,由于材料成分及物性的梯度变化使得材料内部的残余热应力影响了产品的性能。为了分析制备及服役过程中梯度硬质合金中残余应力的影响,通过定义弹性约束因子和引入塑性约束因子得到了材料的弹塑性本构关系,将此本构模型结合有限元方法得到了梯度硬质合金内部残余热应力的分布。数值计算结果表明:残余热应力主要集中在样品近表面的梯度区。在富钴区出现了拉应力,而在表明出现了压应力,表面最大压应力有380 MPa。同时,采用X射线衍射(sinψ)~2法测试了样品的表面应力,得到的结果是–379.75 MPa,实验观测与数值模型符合较好。
Functional Graded Carbide realizes a perfect combination of high hardness and high strength. However, due to the gradient of material composition and physical properties, the residual thermal stress inside the material affects the performance of the product. In order to analyze the influence of the residual stress in the gradient cemented carbide during preparation and service, the elasto-plastic constitutive relation of the material is obtained by defining the elastic constraint factor and introducing the plastic constraint factor. The constitutive model and the finite element method The distribution of residual thermal stress in the alloy. The numerical results show that the residual thermal stress is mainly concentrated in the gradient region near the surface of the sample. Tensile stress appears in the cobalt-rich region, and in the event of compressive stress, the maximum compressive stress on the surface is 380 MPa. At the same time, the surface stress of the sample was tested by X-ray diffraction (sinψ) ~ 2 method and the result was -379.75 MPa. The experimental observation is in good agreement with the numerical model.