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濟南鍍(du)鋅管(guan)可能存(cun)在的內部缺(que)陷 (一)

來源:http://atcasummit.com/ 日期:2019-11-28 發布人:admin

   今天濟南樂豪金屬來給大家講解一下濟南鍍鋅管在生產過程中可能會出現哪些內部缺陷。

  Today, Jinan Lehao metal will tell you what internal defects may appear in the production process of Jinan galvanized pipe.
  鍍鋅管內部缺陷之白點。白點,也稱為發裂,是鍍鋅管的內部裂紋,是不允許存在的一種缺陷。
  White spot of internal defect of galvanized pipe. White spot, also known as crack, is the internal crack of galvanized pipe, which is not allowed to exist.
  大型鍛件冷卻到室溫后,通常會在幾個小時、幾十個小時甚至更長時間后出現白斑。蝕刻后,可以在橫向試樣上觀察到直的、細的和彎曲的裂紋。當裂紋沿垂直于裂紋的方向斷裂時,在裂紋一側的斷裂面上可以發現銀白色的圓形或橢圓形斑點。
  When large forgings are cooled to room temperature, white spots usually appear after several hours, dozens of hours or even longer. After etching, straight, thin and curved cracks can be observed on the transverse specimen. When the crack breaks along the direction perpendicular to the crack, silver white round or oval spots can be found on the fracture surface on one side of the crack.
  一般我們會檢查淬火狀態下的白點,以避免樣品損壞時由于塑性變形造成的白點變形。
  It is better to check the white spot in the quenching state to avoid the white spot deformation caused by plastic deformation when the sample breaks.
濟南鍍鋅管
  不同的學派對白點的產生機制有不同的看法。其中有人認為氫是產生白點的關鍵因素,巨大的內應力是產生白點的另一個重要原因,也就是說,當鋼錠中未逃逸的氫原子聚集在微觀空隙中成為分子態時,鍍鋅管會因體積膨脹而產生較大的內應力。在熱壓加工過程中的變形力和隨后冷卻過程中的熱應力以及組織轉變過程中產生的相變應力的共同作用下,材料內部的局部裂紋白點在宏觀上表現為多個細小的裂紋,這些裂紋從工件內部徑向向外或沿壓力加工變形流動方向(通常稱為流線分布)分布;在其縱向斷裂處,呈現銀白色橢圓形斑點。
  Different schools of thought have different views on the generation mechanism of white dots. Some people think that hydrogen is the key factor to produce the white spot, and the huge internal stress is another important reason to produce the white spot. That is to say, when the hydrogen atoms in the ingot that have not escaped gather in the micro void and become the molecular state, the galvanized pipe will produce larger internal stress due to the volume expansion. Under the combined action of the deformation force in hot pressing process, the thermal stress in cooling process and the transformation stress in the process of microstructure transformation, the white spots of the local cracks in the material are shown as many tiny cracks on the macro level, which are distributed radially from the inside of the workpiece to the outside or along the deformation flow direction (usually called streamline distribution) of the pressure processing; in the longitudinal fracture , showing silver white oval spots.
  因為白點經常成批出現,一些人還聲稱白點是鍍鋅管之病。一些含鎳和鉬的鋼種對白點的形成很敏感。它們被稱為白斑敏感鋼,如5CrNiMo、5CrMnMo等。
  Because white spots often appear in batches, some people also claim that white spots are the cancer of galvanized pipes. Some steels containing nickel and molybdenum are sensitive to the formation of white spots. They are called white spot sensitive steels, such as 5CrNiMo, 5CrMnMo, etc.
  那白點的危害有什么呢?
  What's the harm of white dots?
  白點的存在導致鍍鋅管的機械性能顯著惡化,無法使用。有白點的鍍鋅管在熱處理過程中容易開裂,或者在加工和使用過程中突然出現內部裂紋,導致鍛件報廢。白斑會降低鍍鋅管的塑性韌性和零件的強度。它們是壓力集中點。在交變載荷的作用下,它們很容易成為疲勞裂紋的來源,導致疲勞損傷。因此,鍛件中不允許出現白點。一旦在鍛件中發現白點,也可以以一定的鍛造比重新鍛造,以進行白點焊接。更多資訊可以關注:http://atcasummit.com/
  The existence of white spots leads to the deterioration of the mechanical properties of the steel. The galvanized pipe with white spots is easy to crack in the process of heat treatment, or internal cracks suddenly appear in the process of processing and use, leading to the scrap of forgings. White spot will reduce the plastic toughness of galvanized pipe and the strength of parts. They are the focus of pressure. Under the action of alternating load, they are easy to become the source of fatigue cracks, leading to fatigue damage. Therefore, white spots are absolutely not allowed in forgings. Once white spots are found in forgings, they can also be re forged with a certain forging ratio to carry out white spot welding.

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