对具有两种不同组织状态的一种低碳低合金钢进行了纳米压痕表征. 结果表明, 在双相组织试样中, 马氏体的硬度高于铁素体的70%以上. 在纳米压痕实验过程中, 由于马氏体相的尺寸较小并被软的铁素体 基体所包围, 当压痕深度超过40 nm时, 纳米压痕硬度呈现出明显的 基底效应. 由于在铁素体-奥氏体两相区加工过 程中发生C元素向奥氏体的分配, 双相组织试样中的马氏体中 富集了数倍于钢的名义含量的C元素. 结果导致双相组织 试样中马氏体的平均纳米压痕硬度比同一钢的全马氏体组织 试样高出30%以上. 此外, 还讨论了C的富集分配对马 氏体Poisson比和Young's 模量的可能影响.
A low carbon low alloy steel with two different types of microstructures was characterized by nanoindentation. The results indicate that the average nanoindentation hardness of martensite is at least 70\% higher than that of ferrite in the dual-phase sample. Since the ultrafine martensite grain is embedded in the soft ferrite matrix, the nanoindentation hardness of martensite exhibits a substrate-effect when the indentation depth is over 40 nm. Due to more carbon atoms partitioning to austenite during intercritical process, carbon content of martensite in the dual-phase sample may be several times higher than the nominal carbon content of the steel, which makes the average nanoindentation hardness of martensite in the dual-phase sample is at least 30% higher than that in the fully martensitic sample. In addition, the possible effects of carbon partitioning on Poisson ratio and Young's modulus of martensite were discused briefly.