Control of cementite precipitation in lath martensite by rapid heating and tempering
Control of cementite precipitation in lath martensite by rapid heating and tempering
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DOI：
10.2355/isijinternational.44.1937
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发表时间：
2004-01-01
影响因子：
1.8
通讯作者：
Maki, T
中科院分区：
文献类型：
--
作者：
Furuhara, T;Kobayashi, K;Maki, T
研究了机械结构用合金钢（SCM 435-，Fe-0.35C-0.24Si-0.77Mn-1.05Cr-0.17Mo）在不同温度（723-923 K）下回火时的板条马氏体组织。回火温度和时间相同时，快速加热（100 K/s或1000 K/s）试样的硬度大于缓慢加热（2K/s）试样的硬度。渗碳体沉淀物通过回火在高角度边界（原奥氏体晶界、块和包边界）上以及板条内和低角度边界（板条边界）处形成。TEM观察表明，较细的方解石在快速加热的样品中比在缓慢加热的样品中分散得更均匀。认为提高升温至回火温度的升温速率可提高方解石开始析出的温度，从而提高晶核形成速率，细化方解石的分散。
Lath martensite structures, tempered at various temperatures (723-923 K) were studied by changing heating rates (2 K/s to 1 000 K/s) to the tempering temperature in an alloy steel for machine structural use (SCM435-, Fe-0.35C-0.24Si-0.77Mn-1.05Cr-0.17Mo). Hardness of the rapidly heated (at 100K/s or 1 000 K/s) specimen is larger than that of the slowly heated (at 2 K/s) specimen when tempering temperature and time are the same. Cementite precipitates are formed on high-angle boundaries (prior austenite grain boundary, block and packet boundaries) as well as within laths and at low-angle boundaries (lath boundaries) by tempering. TEM observation has revealed that finer cementite is dispersed more uniformly in the rapidly heated specimen than in the slowly heated specimen. It is considered that the temperature where cementite precipitation starts is raised by increasing the heating rate to tempering temperature, resulting in a higher nucleation rate and a finer dispersion of cementite.