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在20~600℃范围内对国产SA-182 F304钢进行了温度效应下的拉伸行为研究。采用光学显微镜、透射电镜、扫描电子显微镜、XRD以及显微硬度仪对原始态和拉伸断裂试样进行了微观组织与微观化学分析与表征。试验结果表明,在晶粒度为5.5级的钢基体中分布着粗系、moy级别为1.5级的B类和细系、moy级别为1.0级的D类宏观夹杂物,分别占0.0317%和0.0158%,这些夹杂物容易出现在拉伸断口的韧窝处。钢基体中分布着大量平行与缠结的位错,析出相主要为FCC结构的Ti(Cr,Fe,Mn)_2。屈服强度、拉伸强度和伸长率随着温度的升高而降低,而断面收缩率却保持在80%左右,表现出良好的塑性,断口以韧窝为主。拉伸导致了钢基体的显微硬度显著提高,比原始态钢的相应值提高了约一倍。显微硬度的增加来源于钢基体中的位错增殖,而非相变的结果,拉伸并没有导致奥氏体向马氏体发生明显转变。随着拉伸温度升高,奥氏体晶粒的回复加剧,位错密度逐渐降低,纤维状的组织明显降低。
The tensile behavior of domestic SA-182 F304 steel under the temperature effect was studied in the range of 20 ~ 600 ℃. The microstructure and microscopic chemical analysis and characterization of the original and tensile rupture specimens were carried out by optical microscope, transmission electron microscopy, scanning electron microscopy, XRD and microhardness tester. The results show that the coarse grains, the coarse grains, the class B with the moy grade of 1.5 and the class D macroscopic inclusions with the grade of the moy of 1.0 are distributed in the steel matrix with the grain size of 5.5, accounting for 0.0317% and 0.0158 %, These inclusions easily appear in the tensile fracture of the dimple Department. There are a large number of dislocations parallel and entangled in the steel matrix, Ti (Cr, Fe, Mn) _2, mainly FCC structure, precipitated. Yield strength, tensile strength and elongation decreased with the increase of temperature, but the cross-sectional shrinkage rate remained at about 80%, showing good ductility, fracture dimple-based. Tensile results in a significant increase in the microhardness of the steel matrix, which is approximately double that of the original steel. The increase in microhardness results from the dislocation propagation in the steel matrix, whereas the non-phase transformation results in no significant transformation of austenite to martensite. As the drawing temperature increases, the austenite grain recovery increases, the dislocation density decreases gradually, and the fibrous structure decreases obviously.