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一、前言 T203后制动分泵弹簧是设备专用弹簧,长期来按设计要求采用鼓形弹簧。该鼓形弹簧(图1)是由φ12mm的60Si2Mn圆钢经冷卷绕成形后,再进行淬火、回火热处理,最终硬度要求为HRC48。工厂购进成品鼓形弹簧一批,当弹簧装机运转时,突然断成数截,接连数起,致使整机停产。经分析查明,由于用材失误和热处理不当,造成产品报废。二、断口特征分析鼓形弹簧断口平面与钢料轴线约有45°交角,呈螺旋形状(麻花状)。断口由晶粒粗大的闪光小刻面组成,色泽亮灰,具有结晶状断口形貌特征。不太明显的放射区布满整个断面,边缘没有剪切唇。在弹簧内侧面,有一暗点,经体视显微镜放大后观察,暗点实为平行于钢料轴线的台阶。根据放射
First, the foreword T203 brake cylinder spring is a device-specific spring, long-term design requirements by the use of drum-shaped spring. The drum spring (Figure 1) is φ12mm by 60Si2Mn round bar after cold-forming, and then quenching, tempering heat treatment, the final hardness requirements for the HRC48. The factory purchased a batch of drum spring products, when the spring installed capacity, suddenly cut into several sections, after several, resulting in the machine cut-off. After analysis, due to material errors and improper heat treatment, resulting in product scrapped. Second, the fracture characteristics analysis Drum-shaped spring fracture plane and the steel axis about 45 ° angle, was spiral shape (twist-like). Fracture from the coarse grain flash facet composition, light gray color, with crystalline fracture morphology. The less pronounced radial area fills the entire cross-section with no cut lip on the edge. In the inner side of the spring, there is a dark spot, enlarged by the stereo microscope to observe the dark point is actually parallel to the steel axis of the step. According to radiation