Magnetic measurements of the reverse martensite to austenite transformation in a rolled austenitic stainless steel
Magnetic measurements of the reverse martensite to austenite transformation in a rolled austenitic stainless steel
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DOI：
10.1023/b:jmsc.0000017761.64839.fc
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发表时间：
2004-03
影响因子：
4.5
通讯作者：
K. Mumtaz;S. Takahashi;J. Echigoya;Y. Kamada;Lfigong Zhang;H. Kikuchi;K. Ara;M. Sato
中科院分区：
文献类型：
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作者：
K. Mumtaz;S. Takahashi;J. Echigoya;Y. Kamada;Lfigong Zhang;H. Kikuchi;K. Ara;M. Sato
通过磁性测量研究了 304 不锈钢 (SS) 中的逆 (α′-γ) 转变。厚度减少 15% 至 55% 的轧制样品在不同温度和时间下进行退火。在 300–600°C 温度下退火 5 分钟后，与轧制后的饱和磁化强度值相比，饱和磁化强度值有所增加。 500°C 退火后轧制至 40% 至 55% 压下量的样品显示出最高的饱和磁化强度。退火温度高于 625°C 时，饱和磁化强度急剧下降，这表明逆 (α'-γ) 相变开始。当退火时间为5至40分钟时，饱和磁化强度的下降很快，而当退火时间超过40分钟时，饱和磁化强度的下降相对较低。在 300–600°C 之间的温度下，逆 (α'-γ) 转变后的硬度值稍大，这是由于 α' 马氏体的增加，高于此温度，由于恢复和再结晶，硬度大幅下降。结果表明，在 300–500°C 温度范围内，矫顽力下降，这可能是由于 α′ 马氏体相的增加所致。在 500 至 625°C 之间的温度下矫顽力的进一步降低可能归因于从马氏体相中清除了一些位错。随后，在高达 800°C 的温度下矫顽力急剧增加，这归因于形状磁各向异性效应。当温度在 800–;900°C 之间时，矫顽力会迅速下降。在 900–;1100°C 之间的温度下，矫顽力的下降并不是那么明显。超过 800°C 时矫顽力的降低对应于不锈钢由于再结晶而软化。根据饱和磁化强度值的变化，As 温度估计在 625–;650°C 之间，而 Af 则在 900–;950°C 之间。
The reverse (α′-γ) transformation in 304 stainless steel (SS) has been studied by magnetic measurements. Specimens rolled 15 to 55% reduction in thickness were annealed at various temperatures and times. After annealing at temperatures between 300–;600°C for 5 min the saturation magnetization values increased when compared to the saturation magnetization values after rolling. Specimens rolled to 40 to 55% reduction after annealing at 500°C showed the highest saturation magnetization. Saturation magnetization sharply decreases at annealing temperature above 625°C which indicates the start of reverse (α′-γ) transformation. The decrease in saturation magnetization is rapid for annealing time from 5 to 40 min, whereas, the decrease in saturation magnetization is relatively low for annealing time above 40 min. The hardness values after reverse (α′-γ) transformation at temperatures between 300–;600°C is slightly greater attributed to the increase in α′ martensite and above this temperature the hardness dropped substantially as a result of recovery and recrystallization. The results show that there is a decrease in coercive force at temperatures between 300–;500°C and may be due to an increase in α′ martensite phase. A further decrease in coercive force at temperature between 500 and 625°C may be attributed to the sweeping out of some dislocation from the martensite phase. This is followed by a sharp increase in coercive force at temperature up to 800°C and is attributed to a shape magnetic anisotropy effect. At temperatures between 800–;900°C a rapid decreased in coercive force occurs. At temperatures between 900–;1100°C the decrease in coercive force is not so sharp dominant. The decrease in coercive force above 800°C corresponds to softening of the stainless steel due to recrystallization. From the changes in the values of saturation magnetization theAstemperature is estimated to be between 625–;650°C, and theAfto be between 900–;950°C.