摘要
采用激光粉末床熔融(LPBF)技术制备了304L不锈钢,并对其分别进行了600、800、1000和1300℃保温2 h的热处理,研究了热处理温度对其显微组织的影响。结果表明:样品的晶粒尺寸随温度升高呈长大趋势。当热处理温度为1300℃时,样品的晶粒明显粗化。由于LPBF的快速凝固使304L不锈钢中生成了δ铁素体和σ相。δ铁素体相随温度升高发生固溶,含量下降,但当温度升高至1300℃时,δ铁素体含量突然升高,这是是因为发生了奥氏体向高温铁素体的二次转变。热处理对沿晶分布的σ相固溶效果甚微,热处理温度为800℃时,σ相含量突然增加,这是因为800℃是处在σ相的析出温度范围。本研究结果表明,对LPBF 304L不锈钢进行热处理,应尽量避开晶粒粗化、铁素体析出的高温区和σ相析出的中温区。
304 L stainless steel was prepared by laser powder bed fusion(LPBF) technology, and then it was subjected to heat treatment at 600 ℃, 800 ℃, 1000 ℃ and 1300 ℃ for 2 h, and the effect of heat treatment temperature on its microstructure was studied. The results show that the grain size of the sample increases with the increase of heat treatment temperature. When the heat treatment temperature is 1300 ℃, the grains of the samples are significantly coarsened. δ ferrite and σ phases are formed in the 304 L stainless steel due to the rapid solidification characteristic of the LPBF. The δ ferrite phase dissolves with the increase of temperature, and thus the content decreases, but when the temperature increases to 1300 ℃, the δ ferrite content suddenly increases, which is due to the secondary transformation of austenite to high temperature ferrite. The heat treatment has little effect on the solid solution of the σ phase distributed along the grain boundaries, but when the heat treatment temperature is 800 ℃, the content of the σ phase suddenly increases, because the 800 ℃ is in the precipitation temperature range of the σ phase. The results of this study show that the heat treatment of the 304 L stainless steel prepared by LPBF should avoid the high temperature zone of grain coarsening, ferrite precipitation and the middle temperature zone of σ phase precipitation as far as possible.
作者
朱戴根
代斌斌
陈伟
侯娟
黄爱军
ZHU Dai-gen;DAI Bin-bin;CHEN Wei;HOU Juan;HUANG Ai-jun(Academy of Materials,University of Shanghai Science and Technology,Shanghai 200082,China;Monash University,Normanby Road 15-173168,Australia)
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2021年第1期147-154,共8页
Transactions of Materials and Heat Treatment
关键词
粉末床激光熔融
304L不锈钢
热处理
析出相
laser powder bed fusion
304L stainless steel
heat treatment
participated phase
