The outer zone is made up of reticular cells, columnar cells and mucous cells;

外区主要由网状上皮细胞、柱状上皮细胞、黏液细胞组成；

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The results show that:under the no preheating condition, the microstructure of weld metal is columnar austenitic, and brittle martensite exists in the fusion zone and over-heated zone unavoidably.

研究结果表明：在不预热条件下，用KD286焊补钢轨，焊缝组织为柱状奥氏体组织，熔合区和过热区不可避免地产生脆硬的马氏体组织。

youdao

The results show that:under the no preheating condition, the microstructure of weld metal is columnar austenitic, and brittle martensite exists in the fusion zone and over-heated zone unavoidably.

研究结果表明：在不预热条件下，用KD286焊补钢轨，焊缝组织为柱状奥氏体组织，熔合区和过热区不可避免地产生脆硬的马氏体组织。

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