Thermal mechanisms of grain and packet refinement in a lath martensitic steel
Thermal mechanisms of grain and packet refinement in a lath martensitic steel
复制标题
DOI：
10.2355/isijinternational.38.1277
复制
发表时间：
1998-01-01
影响因子：
1.8
通讯作者：
Morris, JW
中科院分区：
文献类型：
--
作者：
Kim, HJ;Kim, YH;Morris, JW
这项工作是为了阐明用于热处理以细化板条马氏体钢的有效晶粒尺寸的冶金机制。本工作所选的合金是Fe-12 Ni-0.25Ti，其在淬火条件下提供了明确的板条马氏体结构。对合金进行了四种典型的热处理：（1）退火和淬火处理，（2）亚温退火，（3）奥氏体范围内的单次或双次退火，以及（4）以快速加热速率向奥氏体的单次或双次回复。两个有效的晶粒尺寸被确定为每个热处理：包的大小，或尺寸超过相邻的马氏体板条有一个共同的结晶取向，和原奥氏体晶粒尺寸。前者控制韧脆转变温度，后者控制晶间脆化。不同的热处理抑制DBTT和增加抵抗晶间脆化的程度，它们降低了相关的晶粒尺寸。快速回复是最成功的热处理，因为它破坏了包内板条的对齐。快速回复容易产生接近1 μ m的有效晶粒尺寸，导致非常低的延性-脆性转变温度和对回火或氢脆的显著抗性。
This work was done to clarify the metallurgical mechanisms that are used in thermal treatments to refine the effective grain size of lath martensitic steels. The alloy chosen for this work was Fe-12Ni-0.25Ti, which provides a well-defined lath martensite structure in the as-quenched condition. The alloy was given four prototypic heat treatments: (1) an anneal-and-quench treatment, (2) an intercritical anneal, (3) a single or double anneal in the austenite range, and (4) a single or double reversion to austenite at a rapid heating rate. Two effective grain sizes were identified for each heat treatment: the packet size, or dimension over which adjacent martensite laths have a common crystallographic orientation, and the prior austenite grain size. The former controls the ductile-brittle transition temperature (DBTT), the latter controls intergranular embrittlement. The different heat treatments suppress the DBTT and increase resistance to intergranular embrittlement to the extent that they decrease the relevant grain size. Rapid reversion is the most successful of the heat treatments since it destroys the alignment of laths within a packet. Rapid reversion readily yields an effective grain size near 1 mu m, leading to a very low ductile-brittle transition temperature and a substantial resistance to temper or hydrogen embrittlement.