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根据拉伸试验(TT)得到的应力-应变曲线和通过声音脉冲方法(APM)得到的声速,计算并比较了烧结钢的弹性模量(E)和泊松比(ν)。Err和νTT的值分别小于EAPM和νAPM,这是因为在烧结钢的应力-应变中不仅包含了弹性应变,而且也包含了塑性应变。利用由EAPM和νAPM的值计算得到的纵向和横向弹性应变,从纵向和横向应力-应变中分离出纵向和横向的塑性应变。在小应变时烧结钢没有显示线性应力-应变的情况下,可以很简单地由纵向塑性应力表中求出弹性极限或0.2%的屈服强度。对于同样的应力,每个样品的弹性应变和塑性应变的不同,可以由基于孔隙特征(孔隙的大小、形状、相互连接及微观结构的不同)的模型来解释。
The elastic modulus (E) and Poisson’s ratio (ν) of sintered steel were calculated and compared according to the stress-strain curve obtained through tensile test (TT) and the velocity of sound obtained by the sound pulse method (APM). The values of Err and νTT are smaller than those of EAPM and νAPM, respectively, because not only the elastic strain but also the plastic strain are included in the stress-strain of the sintered steel. Longitudinal and transverse elastic strains calculated from the values of EAPM and νAPM are used to separate longitudinal and transverse plastic strains from longitudinal and transverse stress-strain. In the case of small strain sintered steels that do not show linear stress-strain, the elastic limit or 0.2% yield strength can be easily determined from a longitudinal plastic stress gauge. For the same stress, the difference between the elastic strain and the plastic strain for each sample can be explained by a model based on the characteristics of the pores (the size, shape, interconnection and microstructure of the pores).