The fracture surface of the normalized steel 55SiMnMo was observed, under tensile testing device equipped on SEM, to be of ductile dimple feature in the bainite which are composed of austenite and ferrite.

• 采用扫描电镜拉伸装置,对55SiMnMo钢正火组织进行拉断观察,发现其断口为微坑型延性断口。