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在扫描电镜下对CL60车轮钢单边缺口薄试样(厚度≤0·5mm)进行了原位拉伸实验,并研究了氢的影响.在金相显微镜下观察了带预裂纹的厚度为30mm的楔形张开加载试样开裂过程.结果表明,对薄试样拉伸变形时,不论是否有氢,先共析铁素体优先发生塑性变形,微裂纹沿先共析铁素体与珠光体团的边界形核、扩展;在有氢的情况下,微裂纹更容易通过夹杂物的剥落或夹杂物与基体界面的分离而萌生;薄试样拉伸主要是韧窝断口;对厚试样,裂纹主要通过珠光体中渗碳体片层开裂而扩展,断口也因此主要呈解理特征.
Under the scanning electron microscope (SEM), the in-situ tensile test was carried out on the single-side notched thin plate (thickness ≤0.5 mm) of CL60 wheel steel and the influence of hydrogen was studied. The thickness of pre-cracked plate was observed under a metallographic microscope The results show that the pre-eutectoid ferrite preferentially undergoes plastic deformation in the tensile deformation of the thin specimen with or without hydrogen, and the micro-cracks along the pro-eutectoid ferrite and the pearlite In the presence of hydrogen, microcracks are easier to sprout through the detachment of inclusions or the separation of inclusions from the interface of the matrix. The thin specimens are mainly dimpled fractures, and the thick specimens , The crack propagates mainly through the cracking of the cementite lamella in the pearlite, and the fracture is therefore mainly in the cleavage characteristic.