稳定化处理对347H不锈钢第二相及性能的影响

通过JMatPro软件对347H不锈钢相图进行模拟,并结合生产工艺分析其稳定化温度对第二相、力学性能及耐腐蚀性能的影响。结果表明:347H钢凝固过程中第二相主要为NbN、Nb(C,N)、M₂₃C₆、σ相和Z相。1140 ℃固溶后的第二相主要为Nb(C, N)和少量NbN、M₂₃C₆,相尺寸约为0.5 μm。经800~1000 ℃稳定化退火处理后,晶粒尺寸随稳定化温度的增加变化较小,晶粒度为7.5级,第二相随稳定化温度的升高,尺寸显著长大到5 μm以上,经EDS分析表明,数量增加和长大的第二相主要为NbC。800 ℃和850 ℃稳定化退火后347H钢的屈服强度较高,抗拉强度随稳定化温度的升高变化不大。稳定化退火后347H钢的腐蚀速率较固溶态的腐蚀速率低,稳定化退火提升了347H钢的耐晶间腐蚀性能。

Effect of stabilization treatment on second phase and properties of 347 H stainless steel

Phase diagram of the 347H stainless steel was simulated by JMatPro software, and the effect of stabilization temperature on second phase, mechanical properties and corrosion resistance were analyzed. The results show that the second phase of the 347H steel during solidification is mainly NbN, Nb(C,N), M₂₃C₆, σ phase and Z phase. The second phase after solid solution at 1140 ℃ is mainly Nb (C, N) and a small amount of NbN and M₂₃C₆, with the size of about 0.5 μm.After stabilization at 800-1000 ℃, the grain size of the steel plate changes little with the increase of stabilization temperature,and the grain size is 7.5 grade. With the increase of stabilization temperature, the size of the second phase grows significantly to over 5 μm, and EDS analysis shows that NbC is the main secondary phase. The yield strength of the 347H steel stabilized at 800 ℃ and 850 ℃ is higher, and the tensile strength changes little with the increase of stabilizing temperature. The corrosion rate of the stabilized steel is lower than that of the solid solution state, and the intergranular corrosion resistance of the 347H steel is improved.