保护气氛电渣重熔H13模具钢组织和性能研究

Research on microstructure and performance of die steel H13 produced by gas-protective ESR furnace

邢台钢铁有限责任公司利用具有保护气氛的抽锭式电渣炉生产Ф600 mm的H13钢锭,并锻造成不同规格的模块。研究了熔速对铸态组织的影响以及锻造工艺对H13钢显微组织和冲击性能的影响。结果表明：在400-550 kg·h^-1熔速范围内,钢锭铸态组织中都存在不同程度的枝晶间显微偏析,并有液析碳化物析出。熔速为500 kg·h^-1时,铸态组织显微偏析较轻,液析碳化物尺寸较小,且数量较少。在500 kg·h^-1熔速下生产的钢锭经不同的锻造工艺变形后发现,只进行单向拔长变形的组织中存在明显的带状偏析,枝晶未被打碎,仍保留了铸态的针状铁素体组织;一镦一拔变形后的组织,铁素体位向逐渐趋于等轴状,碳化物均匀分布程度有提高,但晶界上仍有呈链状析出的碳化物,带状组织未完全消除;三镦三拔多方向反复变形后,枝晶被充分打碎,带状偏析消除,锻后退火组织中的粒状珠光体和碳化物细小均匀,横向冲击韧性明显提高,达到15.5 J·cm^-2。

Die steel H13 with diameter of Ф600 mm was produced by gas-protective retracting-type ESR furnace in Xingtai Iron and Steel Corporation,and it was forged into parts of different specifications. The influence of melt rate and forging process on structure and impact toughness of H13 were studied. The results show that when the melt rate is between 400-550 kg·h^-1,there are dendrite micro segregation and eutectic carbides in H13 ESR ingot. When the melt rate is up to 500 kg·h^-1,dendrite micro segregation is lighter,the size of eutectic carbide in H13 ESR ingot is smaller and its number is less. The ingot which was produced by melt rate 500 kg·h^-1was forged by different processes. The results show that when the ingot is forged by single direction deformation,there are obvious banded structure and casted needle ferrite without broken dendrite; when it is forged by one forging and one pull deformation,the ferrite structure becomes equiaxed shape gradually and distribution of carbides comes more homogeneous. However,chained carbides separates out on the boundary of grain and banded structure is not completely eliminated; when it is forged by three-forging and three-pull multi-direction deformation,dendrite is broken sufficiently,banded structure is eliminated,granular pearlite and carbide are fine and uniform in annealing organization after forging,and the transverse impact toughness is obviously improved up to 15. 5 J·cm^-2.