Microstructural modifications and changes in mechanical properties during cyclic heat treatment of 0.16% carbon steel
Microstructural modifications and changes in mechanical properties during cyclic heat treatment of 0.16% carbon steel
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DOI：
10.1016/j.msea.2011.11.095
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发表时间：
2012-02
期刊：
影响因子：
6.4
通讯作者：
A. Saha;D. Mondal;K. Biswas;J. Maity
中科院分区：
文献类型：
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作者：
A. Saha;D. Mondal;K. Biswas;J. Maity
在这项工作中，退火的0.16wt%碳钢经受循环热处理过程，该过程包括在910°C（高于Ac 3温度）下反复短时间（6 min）保持，然后强制空冷。一个典型的显微组织的发展，不那么常见的低碳亚共析钢，观察。其主要特征是：（i）晶粒明显细化（主要在初始阶段），（ii）位错的产生（在初始阶段）和位错的湮灭（在后期阶段），（iii）由于离异共析反应，产生了由碲酸盐和碲酸盐团组成的晶界网络。在低碳钢中，大比例的晶界区域的存在促进了碳在短时间保持期间的晶界扩散。这一现象最终通过离异共晶反应导致晶界的网状结构和团簇结构的形成。与高碳钢不同，离异共晶反应对球化的贡献不大。对于更高的循环（5-8个循环），大量存在的晶界铁和铁团恶化的强度性能。然而，相当高的强度（UTS= 455 MPa）实现了这种低碳钢与两个循环的热处理由于细铁素体晶粒尺寸，高位错密度和足够比例的细片状珠光体的组织。
In this work an annealed 0.16wt% carbon steel was subjected to cyclic heat treatment process that consisted of repeated short-duration (6min) holding at 910°C (above Ac3temperature) followed by forced air cooling. A typical microstructural development, not so common for low carbon hypoeutectoid steel, was observed. The main features involved were: (i) a substantial grain refinement (mainly at initial stage), (ii) generation of dislocations (at initial stage) and its annihilation (at later stage) and (iii) generation of grain boundary network of cementite and cementite cluster owing to divorced eutectoidal reaction. In low carbon steel, the presence of large proportion of grain boundary areas promoted grain boundary diffusion of carbon during short-duration holding. This phenomenon finally led to the generation of grain boundary cementite network and cluster through divorced eutectoidal reaction. Unlike high carbon steel, the contribution of divorced eutectoidal reaction to spheroidization was not so significant. For higher cycles (5–8 cycles) substantial presence of grain boundary cementite and cementite cluster deteriorated the strength property. However, quite a high strength (UTS=455MPa) was achieved for this low carbon steel with two cycles of heat treatment due to fine ferrite grain size, high dislocation density and adequate proportion of fine lamellar pearlite in the microstructure.