摘要
采用合适的渗铝氧化处理工艺在CLAM钢基体表面制备了铝化物涂层,然后利用XRD、EPMA、SEM、纳米压痕仪、室温拉伸试验机等手段研究了渗铝氧化处理前后组织和力学性能变化,尤其是涂层的相组成变化,进而详细分析了硬度变化和拉伸断口的断裂机制。结果表明,渗铝氧化处理后在CLAM钢表面形成了由约30.8μm厚的FeAl相层和约70.7μm厚的α-Fe(Al)固溶体层组成的铝化物涂层,最外层FeAl相的硬度最大为834.7 HV,由外向内硬度逐渐降低至315.1 HV,基体内部的硬度出现略微回升。CLAM钢在渗铝氧化前后的抗拉强度分别为581.38 MPa和555.83 MPa,断后伸长率分别为30%和28%,断裂模式由渗铝氧化前的韧性断裂变成准解理断裂。由于渗铝及氧化热处理导致的晶粒尺寸增大和第二相粒子聚集,CLAM钢在渗铝氧化后拉伸性能下降,同时在表面涂层处易产生裂纹源从而加速材料断裂。
The aluminide coating was prepared on the surface of CLAM steel substrate by a suitable aluminizing and oxidation, then the microstructure and mechanical properties, especially the phase composition changes of the coatings before and after aluminizing and oxidation treatment were studied by means of XRD, EPMA, SEM, nanoindenter and room temperature tensile testing machine, as well the hardness changes and fracture mechanism of tensile fracture were analyzed in detail. The results show that after aluminizing and oxidation treatment, an aluminide coating composing of a 30.8 μm thick layer of FeAl phase and a 70.7 μm thick layer of α-Fe(Al) solid solution is formed on the surface of the CLAM steel. The hardness of the coating is up to 834.7 HV for the outermost FeAl phase, and gradually decreases to 315.1 HV from the outside to the inside, while the hardness inside the steel substrate rises slightly. The tensile strength of CLAM steel before and after aluminizing and oxidation is 581.38 MPa and 555.83 MPa, respectively, and the elongation after fracture is 30% and 28%, respectively. The fracture mode is changed from ductile fracture before aluminizing and oxidation to quasi-cleavage fracture. After aluminizing and oxidation, the tensile property of the CLAM steel is degraded and the crack sources are prone to be generated at the surface coating to accelerate the material fracture, which is due to the grain size increasing and the secondary phase particle aggregation caused by the aluminizing and oxidation treatment.
作者
赵小军
梁晓
蔡圳阳
肖来荣
Zhao Xiaojun;Liang Xiao;Cai Zhenyang;Xiao Lairong(School of Materials Science and Engineering,Central South University,Changsha Hunan 410083,China)
出处
《金属热处理》
CAS
CSCD
北大核心
2022年第1期192-196,共5页
Heat Treatment of Metals
关键词
CLAM钢
渗铝氧化
显微组织
纳米压痕
断口分析
CLAM steel
aluminizing and oxidation
microstructure
nanoindentation
fracture analysis
