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1991年11月初,正值我厂新制BD1型宽体地铁电动客车进入紧张的整体组焊阶段,用于车门立柱、底架横梁等部位的厚4.5mm的A3钢板,在冲孔和弯制成型中却出现了严重的裂纹和断裂现象,致使车辆钢结构配件无法进行生产。面对这种生产状况,我们及时取样观察了断裂钢板的宏观断口形态和微观金相组织。初步分析认为,造成钢板开裂的内在因素是钢板中存在带状组织。基于这种分析,我们参阅了《金属热处理》1990年第5期中彭展里同志发表的《20钢板冷冲压产生裂纹的原因及解决的力法》一文。结合我厂设备情况,制定出正火(900℃×15min)+
At the beginning of November, 1991, the newly-built BD1 wide-body metro electric bus of our factory entered into the intense whole welding stage. The A3 steel plate with a thickness of 4.5mm for the door column, crossbeam and other parts of the carcass was punched and bent However, serious cracks and ruptures appear in the model, which makes the steel structure parts of the vehicle unable to be produced. In the face of this production situation, we promptly observed the macro fracture morphology and microstructure of the fracture plate. Preliminary analysis shows that the internal factors that cause the cracking of the steel sheet are the presence of banded structure in the steel sheet. Based on this analysis, we refer to the article entitled “Causes and Solutions of Cracks Caused by Cold Stamping of Steel Plate 20” published by Peng Zengli in “Metal Heat Treatment”, No. 5, 1990. Combined with our plant equipment, to develop a normalized (900 ℃ × 15min) +