升降货梯链条故障分析

升降货梯http://www.sdsjpt.net/链条是升降货梯中的关键部件，对于升降货梯的安全使用具有重要的意义。升降货梯链条一般采用高碳优质碳素结构钢或低合金钢制造，其最终热处理状态为正火后低温回火，齿条显微组织状态对齿条性能具有重要的影响。
Cargo lifter cargo lifter chain is a key component for the safe use of lifting freight elevator has important significance. Cargo lifter chain generally use high-quality carbon-carbon or low-alloy structural steel fabrication, the final heat treatment for normalizing after tempering, rack microstructure state has an important influence on the performance of the rack. 
升降货梯http://www.sdsjpt.net/链条在搬运过程中摔断，齿条材料为60钢，其最终热处理状态为正火后低温回火。对断裂齿条断口进行微观观察和能谱分析，对比分析齿条金相组织，并对其化学成分和力学性能进行分析，查找其断裂失效的原因。断口微观形貌为河流花样，即典型的解理断裂特征。因此，齿条的断裂性质为冲击载荷所致的脆性断裂。根据试验结果，得出齿条断裂与以下因素有关:组织状态断裂齿条的显微组织由珠光体和铁素体组成,属典型的正火组织,但铁素体呈网状分布。由于铁素体的硬度、强度均较低,这种组织属不良组织缺陷,网状铁素体的存在会显著弱化晶界强度。
Cargo lifter chain broke during transportation, rack material is 60 steel, the final heat treatment and tempering after normalizing state. Rack micro fracture fracture observation and EDS analysis, comparative analysis of the microstructure of the rack, and analyze the chemical composition and mechanical properties, the failure to find the cause of the fracture. Fracture morphology of river patterns, namely the typical cleavage fracture characteristics.Therefore, the nature of the fracture due to impact loading rack for brittle fracture. According to the test results, obtained with the rack fracture following factors: the state of the microstructure of the organization by breaking the rack consisting of ferrite and pearlite, which is typical of normalizing organization, but takes the shape of the distribution network of ferrite. Because ferrite hardness, strength are low, this is a poorly organized tissue defects.Mesh presence of ferrite grain boundaries is significantly weakened strength.

从热处理工艺角度看,形成网状铁素体的主要原因是齿条加热和冷却方式不当,正火加热温度过高,出现了粗大的奥氏体晶粒,后序冷却过程中又采用了较快的冷却方式,从而导致先共析铁素体沿奥氏体晶界呈网状析出。断裂齿条与完好齿条相比,铁素体也明显呈网状分布,但前者的晶粒更粗大。由此可见,正火加热和冷却方式不当,造成齿条的晶粒粗大并且铁素体呈网状分布,是升降货梯齿条断裂的因素之一。
From the perspective of the heat treatment process, the main reason for the formation of ferrite is mesh rack improper heating and cooling mode, normalizing the heating temperature is too high, there has been the coarse austenite grains during cooling and subsequent use of a more rapid cooling, resulting in eutectoid ferrite reticular precipitates along the austenite grain boundaries. Compared with the intact fracture rack rack, ferrite significantly reticular distribution, but the former is more coarse grains. Thus, normalizing improper heating and cooling, resulting in coarse grains rack takes the shape of the distribution network and ferrite, is one of the factors Huoti rack fracture.