升降貨梯http://www.s8309.cn/鏈條是升降貨梯中的關(guān)鍵部件，對于升降貨梯的安全使用具有重要的意義。升降貨梯鏈條一般采用高碳優(yōu)質(zhì)碳素結(jié)構(gòu)鋼或低合金鋼制造，其最終熱處理狀態(tài)為正火后低溫回火，齒條顯微組織狀態(tài)對齒條性能具有重要的影響。
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. 
升降貨梯http://www.s8309.cn/鏈條在搬運過程中摔斷，齒條材料為60鋼，其最終熱處理狀態(tài)為正火后低溫回火。對斷裂齒條斷口進行微觀觀察和能譜分析，對比分析齒條金相組織，并對其化學(xué)成分和力學(xué)性能進行分析，查找其斷裂失效的原因。斷口微觀形貌為河流花樣，即典型的解理斷裂特征。因此，齒條的斷裂性質(zhì)為沖擊載荷所致的脆性斷裂。根據(jù)試驗結(jié)果，得出齒條斷裂與以下因素有關(guān):組織狀態(tài)斷裂齒條的顯微組織由珠光體和鐵素體組成,屬典型的正火組織,但鐵素體呈網(wǎng)狀分布。由于鐵素體的硬度、強度均較低,這種組織屬不良組織缺陷,網(wǎng)狀鐵素體的存在會顯著弱化晶界強度。
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.

從熱處理工藝角度看,形成網(wǎng)狀鐵素體的主要原因是齒條加熱和冷卻方式不當,正火加熱溫度過高,出現(xiàn)了粗大的奧氏體晶粒,后序冷卻過程中又采用了較快的冷卻方式,從而導(dǎo)致先共析鐵素體沿奧氏體晶界呈網(wǎng)狀析出。斷裂齒條與完好齒條相比,鐵素體也明顯呈網(wǎng)狀分布,但前者的晶粒更粗大。由此可見,正火加熱和冷卻方式不當,造成齒條的晶粒粗大并且鐵素體呈網(wǎng)狀分布,是升降貨梯齒條斷裂的因素之一。
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.