少无氧扩散处理对热浸镀铝奥氏体钢氧化开裂影响的实验研究
Experimental Study of the Effect of Diffused Heat Treatment with Little or No Oxygen on High Temperature Oxidation Cracks of Hot-dip Aluminizing Austenitic Stainless Steel
熊玮，王国强，贾涓
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作者单位：武汉科技大学钢铁冶金及资源利用省部共建教育部重点实验室
中文关键字：少无氧扩散；热浸镀铝；奥氏体不锈钢；抗高温氧化；开裂
英文关键字：diffused heat treatment with little or no oxygen; hot dip aluminum; austenitic stainless steel; high temperature oxidation-resistance; crack
中文摘要：对扩散热处理后的热浸镀铝1Cr18Ni9Ti奥氏体不锈钢进行1000℃高温氧化试验，发现直接扩散处理试样在氧化120h后表面出现明显的开裂现象，而少无氧扩散处理试样经500h氧化后表面完好。通过金相显微镜、扫描电镜和能谱仪的观察及分析表明，由于扩散前期在外扩散层形成的Fe-Al合金（脆性相Fe2Al5和条状FeAl2）为氧提供了扩散通道，导致直接扩散试样的合金层内产生了内氧化空洞，在高温氧化阶段，内氧化占据主导地位，使镀层表面开裂。少无氧扩散能够防止氧进入合金层内部，而且随着扩散的进行，合金层的相组成及形态变化也对氧向内扩散起阻碍作用。少无氧扩散试样的高温氧化由外向内进行，延缓了合金层的开裂和脱落。
英文摘要：Tests of oxidation resistance at 1000℃ had been done on hot-dip aluminizing austenitic stainless steel after diffused heat treatment. Some cracks appeared on the surface of specimen with heat treatment in the air after oxidation for 120 hours. By contrast, an unbroken surface was obtained after oxidation for 500 hours by heat treatment with little or no oxygen. The analysis by optical microscope, SEM and EDS showed that Fe-Al alloys (brittle Fe2Al5 and strip-type FeAl2) in outer diffusion layer provide diffusing channel for oxygen in the former period of diffused heat treatment. Heat treatment in the air can cause internal oxidation voids in alloy layer. Internal oxidation is dominant during high temperature oxidation. This leads to cracks in the surface. Heat treatment with little or no oxygen can prevent oxygen from entering alloy layer. Alloy phase compositions and forms are changing with the heat treatment going on, which could also hinder the diffusion of oxygen into the matrix. The oxygen at high temperature is from outside to inside for specimen after heat treatment with little or no oxygen. This could delay the cracks and spalling of alloy layer.