本文通过光学显微镜、X射线衍射、电子显微镜(透射和扫描电镜)、紧凑拉伸等试验方法研究了55SiMnMo钢在正火状态下的上贝氏体形态,回火转变以及对其机械性能的影响。 该钢经900℃,0.5h奥氏体化后空冷所出现的上贝氏体形态由铁素体和30—35％富碳奥氏体片层相间组成。未发现有碳化物存在。 这种形态的上贝氏体会发生回火转变,析出碳化物的回火转变温度约为400℃,此时金相组织变为由铁素体、碳化物和3—5％奥氏体组成,作者暂称这种组织为回火贝氏体。在发生回火转变时,裂纹扩展速率(da/dN)随回火温度增加而增加,在400℃时达最大值;断口的扫描电子金相从准解理型过渡到解理型。
The morphology of upper bainite in a 55SiMnMo steel under normalized condition as well as its transformation in tempering has been observed by optical microscopy, TEM, SEM and X-ray diffraction. After austenitising at 900℃ for 1/2h and A. C., the upper bainite resulted was composed of ferrite and 30—35% carbon enriched austenite platelet, however, no carbide appeared until tempering treatment. The tempering temperature for carbide precipitation was found to be 400℃, and the tempering products, so called "tempered bainite", consist of ferrite, carbide and 3—5% austenite. The rate of crack propagation da/dN of the steel increases with the increase of tempering temperature and reaches its maximum at about 400℃, accompanied with relevant change of fracture type from the quasicleavage to the cleavage.
参考文献
| [1] |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%