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Ventilation pipeline is an important facility for building ventilation. It plays an important role in ventilation and ensuring indoor air circulation. Generally speaking, it is made of metal materials. However, some ventilation pipes need to deliver high temperature air. Jinan Ventilation Pipeline Manufacturing Enterprise summarizes the following points:

蠕變:鋼在高溫外力作用下，隨著時(shí)間的延長，會(huì)緩慢而連續(xù)地產(chǎn)生塑性變形，稱為蠕變。鋼的蠕變特性與溫度和應(yīng)力密切相關(guān)。當(dāng)溫度或應(yīng)力增加時(shí)，蠕變速度加快。因此，鍋爐、蒸汽管道、壓力容器等長期高溫運(yùn)行的鋼材應(yīng)具有良好的蠕變抗力，以防止蠕變引起的大量變形，導(dǎo)致結(jié)構(gòu)斷裂和爆炸等惡性事故。

Creep: Under the action of high temperature external force, steel will produce plastic deformation slowly and continuously over time, which is called creep. Creep properties of steel are closely related to temperature and stress. The creep rate increases with the increase of temperature or stress. Therefore, steel products such as boilers, steam pipes, pressure vessels and other long-term high-temperature operation should have good creep resistance to prevent a large number of deformation caused by creep, leading to structural fracture and explosion and other malignant accidents.

球狀化處理和石墨化:在高溫的作用下,碳鋼的滲碳體將遷移和聚集能量,形成的滲碳體在鐵氧體粗粒和混合,球從片狀滲碳體將逐漸改變,稱為球狀化處理。由于石墨的強(qiáng)度很低，而且出現(xiàn)在片狀，使材料的強(qiáng)度大大降低，脆性增加，稱為材料的石墨化。

Spherical treatment and graphitization: Under the action of high temperature, the cementite of carbon steel will migrate and accumulate energy. The cementite formed is mixed with coarse ferrite particles, and the sphere will gradually change from flake cementite, which is called spheroidization treatment. Graphite is called graphitization of materials because of its low strength and flaky appearance, which greatly reduces the strength and increases the brittleness of materials.

熱疲勞性能。鋼結(jié)構(gòu)長期處于冷熱交替狀態(tài)，在溫差變化引起的熱應(yīng)力作用下，材料內(nèi)部會(huì)產(chǎn)生細(xì)小的裂紋，導(dǎo)致斷裂。因此，在溫度波動(dòng)的工況下，鋼的結(jié)構(gòu)和管道應(yīng)考慮熱疲勞性能。

Thermal fatigue properties. The steel structure is in the alternating state of heat and cold for a long time. Under the action of thermal stress caused by temperature difference, tiny cracks will occur inside the material, leading to fracture. Therefore, in the case of temperature fluctuation, the thermal fatigue properties of steel structures and pipes should be considered.

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