Abstract To understand work hardening behavior during low-cycle loading, ductile cast iron containing 10.1 vol% spheroidal graphite, 19.6 vol% pearlite, and ferrite matrix was investigated in an in situ neutron diffraction study of up to four cycles of tensile–compressive loading with applied strains of ±0.01. The amplitudes of applied stress, Bauschinger stress, and Bauschinger strain were found to increase with increasing cycle number, indicating work hardening as cyclic loading progressed. Absolute values of ferrite lattice strain at maximum and minimum applied strains increased with increasing cycle number, indicating an increase in ferrite strength. Consequently, the stress contribution to the strength from ferrite increased as cyclic loading progressed. Cementite embedded in pearlite behaved as the hardest phase and maintained elastic deformation, but its stress contribution to strength was limited because the volume fraction was only about 2.2%. Meanwhile, graphite accommodated little stress. The increase in ferrite strength, caused by dislocation accumulation in ferrite during cyclic loading, played an important role in the work hardening of the ductile cast iron.

中文翻译：

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循环拉压下球墨铸铁的中子衍射监测

摘要 为了了解低周载荷期间的加工硬化行为，在多达四次拉伸 - 压缩载荷循环的原位中子衍射研究中研究了含有 10.1 vol% 球状石墨、19.6 vol% 珠光体和铁素体基体的球墨铸铁。施加的应变为 ±0.01。发现外加应力、包辛格应力和包辛格应变的幅度随着循环次数的增加而增加，表明随着循环载荷的进行加工硬化。施加最大和最小应变时铁素体晶格应变的绝对值随着循环次数的增加而增加，表明铁素体强度增加。因此，随着循环加载的进行，铁素体对强度的贡献增加。嵌入珠光体中的渗碳体表现为最硬的相并保持弹性变形，但其应力对强度的贡献有限，因为其体积分数仅为 2.2% 左右。同时，石墨承受的应力很小。循环加载过程中铁素体中位错积累引起的铁素体强度增加对球墨铸铁的加工硬化起到了重要作用。