正火对EH36级船板钢低温时效冲击性能的影响

Effect of normalizing on impact property of EH36 grade shipbuilding steel after low temperature ageing

针对韶钢热轧宽板厂生产的60 mm厚EH36级船板钢,分别取正火前后的试样进行时效冲击试验。试验结果表明,正火后的EH36级船板钢,从表面至心部组织一致,晶粒细小且均匀分布,-40℃时效冲击合格,低温时效性能得到了显著提高。对正火处理后的EH36级船板钢的间隙原子C、N的分布、位错的变化及组织演化对时效性能的影响进行了初步的分析和讨论。分析结果表明,正火后铁素体中C、N原子的过饱和度下降,以及位错形态的变化、位错密度的降低是导致时效冲击性能提高的主要原因。

Ageing impact tests were conducted for the samples of 60 mm EH36 grade shipbuilding steel produced by the Hot Rolled Wide Plate Plant of Shaosteel. The results showed that EH36 grade shipbuilding steel had homogeneous microstructure and fine grains from the surface to matrix, as well as qualified ageing impact property at -40℃ which indicated significantly improved impact property after low temperature ageing. The influence of such factors as the distribution of interstitial atoms C and N, the dislocation variation and the microstructure evolution on the ageing property of EH36 grade shipbuilding steel after normalizing was analyzed and discussed. The results showed that the degree of supersaturation of C and N atoms in ferrite after normalizing decreased, the dislocation morphology changed, and lower dislocation density was the main reason for improved ageing impact property.