水轮发电机组铸钢件冶炼及热处理工艺

Smelting and Heat Treatment Process of Cast Steel in Water Turbine-generator Set

为了满足铸钢件的性能,冶炼过程首先要求控制钢液中C、Cr、Ni等合金元素在一定范围内,其次要控制钢液中N、H、O含量。通过对超低碳不锈钢试样的热处理工艺对比,研究了不同热处理工艺对力学性能的影响。结果表明,该铸钢件的Nieq/Creq≥0.42,δ-Fe含量<5%。优化后的热处理工艺为:正火1 040℃,一次回火600~630℃,二次回火580~600℃。热处理后铸钢件组织中的奥氏体量达到10.1%,能够显著提高铸件的强度、伸长率、冲击功等性能指标。

In order to meet the performance of cast steel, the first step in the smelting process was to control the content of C, Cr, Ni and other alloy elements in molten steel within a certain range, and the second step is to control the content of N, H and 0 in molten steel. The effects of different heat treatment processes on mechanical properties of ultra-low carbon stainless steel samples were studied by comparing their heat treatment processes. The results show that the cast steel is Nieq/Creq≥0.42, and the 8-Fe content is less than 5%. The optimized heat treatment process normalizing temperature is 1040 ℃, and the first tempering temperature is 600-630 ℃, the secondary tempering temperature is 580-600 ℃. After heat treatment, the austenite volume in the cast steel structure reached 10.1%, which can significantly improve the strength, elongation and impact power and other performance of the casting.