两种渗碳乙烯裂解管的研究

Study of Ethylene Cracking Tubes Carburized under Two Conditions

对实验室固体渗碳（Ｐ管）和裂解炉运行渗碳（Ｓ管）的乙烯裂解管进行了研 究。结果表明，两种渗碳管的组织、合金元素分布及导磁性存在着显著差别。Ｐ管 渗层中二次碳化物量大，非渗层中无二次析出，而Ｓ管则相反。Ｐ管渗层及非渗层 基体的铬含量均高于Ｓ管。在试验条件下，随频率降低，Ｐ管导磁层厚度减少，而 Ｓ管不受影响。

The ethylene cracking tubes pack-carburized in a laboratory(P tube) and carburized during servicing in a cracking furnace (S tube) are studied. It is shown that the microstructures, alloying element distribution and magnetic conductivity of P tude remarkably differ from those of S tube. For P tube, many secondary carbides precipitate in carburized layer rather than in noncarburized layer. However, S tube is otherwise. Chromium contents of matrix in carburized and noncarburized layers of P tube are higher than those of S tube. With reducing frequency. the thickness of magnetic conducting layer of P tube decreases and that of S tube is almost constant.