S355NL鋼低溫沖擊韌度不合格原因分析S355NL鋼低溫沖擊韌度不合格原因分析Cause Analysis of Low-temperature Impact Toughness Disqualification of S355NL Steel 針對某批次S355NL鋼沖擊韌度不合格的現象，從鋼板的化學成分、力學性能、顯微組織、夾雜物及斷口等方面進行了分析，并重點對冶煉、連鑄、軋制工序的主要參數進行了探討。結果表明：晶粒尺寸不均勻、雜質顆粒粗大是導致S355NL鋼沖擊韌度低的主要原因。通過優化冶煉工藝制度以控制化學成分和夾雜物，優化軋制工藝參數以保證鋼板的晶粒度，有效地提高了S355NL鋼沖擊韌度的合格率。 For the phenomenon of low-temperature impact toughness disqualification of S355NL steel, the steel plates were analyzed from the aspects of chemical composition, mechanical property, microstructure, inclusions, fracture and so on. The main parameters of the smelting, continuous casting, the rolling process were discussed with an emphasis. The results show that:the non-uniform grain size and coarse impurity particles were the main reasons leading to the low impact toughness of S355NL steel. By optimizing the smelting process to control the chemical compositions and inclusions, and optimizing the rolling process parameters to ensure the grain size of the steel plates, the qualified rate of the impact toughness of the S355NL steel was effectively improved.
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