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用金相、X光、物理性质测定等方法研究了铁锰合金中的六方马氏体相变。研究结果表明,马氏体形核地点有继承性。用金相和磁性相结合的方法排除了立方马氏体参与所研究相变的可能性,这就肯定了所研究的结果是六方ε马氏体的特殊行径。实验结果从一个新的角度说明了,Fe-Mn合金中γ→ε马氏体相变伴随有很小的自发形变。实验事实还表明,有恒温的γ→ε马氏体相变存在,在15℃到0℃之间恒温转变效应最明显。反复相变时,ε相的量有明显的变化,但铁磁性的立方马氏体并不生成(至少是其变化量在可以发觉的范围以下),这不利于认为六方马氏体是中间相的假说。反复相变使M_s降低,A_s、A_f,升高,从而引起正反向马氏体相变热滞的增加。在γ(?)ε相变时伴随有电阴的变化。在本研究所用合金中,γ→ε相变时电阻下降,而ε→γ相变时电阻升高,也即六方马氏体具有较低的电阻率,从金属电子论角度看,这是很值得进一步研究探讨的问题。对不同添加剂的研究表明,Ni、Cr、Co等合金元素对奥氏体起稳定化作用,其中尤以Ni为最显著。碳对奥氏体的稳定化作用特别强,强烈地降低六方马氏体的相变点M_s,并使ε马氏体量减少。多次反复相变,对Fe-Mn系合金的机械性能有明显的影响。强度、硬度增加,冲击韧性略有下降,这主要是六方马氏体生成的结果。这对生产无磁钢的工艺提出了一个应该考虑到的方面。
The phase transformation of hexagonal martensite in Fe-Mn alloy was studied by means of metallography, X-ray and physical property measurement. The results show that martensite nucleation sites have inheritance. The combination of metallography and magnetism precludes the possibility of cubic martensite participating in the phase transformation under study, which affirms that the result of the study is a special behavior of hexagonal ε-martensite. Experimental results from a new point of view, Fe-Mn alloy γ → ε martensitic transformation with a small spontaneous deformation. Experimental results also show that there is a constant temperature γ → ε martensitic transformation exists, the most obvious temperature-dependent transformation between 15 ℃ to 0 ℃. When the phase change is repeated, the amount of the ε phase changes significantly, but the ferromagnetic cubic martensite is not generated (at least, the variation is below the detectable range), which is not conducive to considering hexagonal martensite as the intermediate phase Hypothesis. Repetitive phase change decreases M_s, A_s, A_f, and thus increases the thermal hysteresis of the positive and negative martensitic transformations. In the γ (?) Ε phase transition accompanied by changes in the cathode. In the alloys used in this study, the resistance decreases when γ → ε changes and the resistance increases when ε → γ changes, that is, the hexagonal martensite has a lower resistivity, which is very good from the viewpoint of metal electron theory Worth further research to explore the issue. Studies on different additives show that alloying elements such as Ni, Cr and Co stabilize austenite, especially Ni is the most significant. The effect of carbon on austenite stabilization is particularly strong, strongly reducing the M_s martensitic transformation point and decreasing the amount of ε martensite. Multiple repeated transformation, the mechanical properties of Fe-Mn alloys have a significant impact. Strength, hardness increased, the impact toughness decreased slightly, which is mainly the result of hexagonal martensite. This puts forward one aspect that should be taken into consideration for the production of magnetless steel.