热加工工艺对铁素体型富Cu高强钢纳米强化相析出行为的影响

    Effect of Hot Working Technology on Precipitation Behavior of Nanoscale Strengthening Phase in Ferritic Cu-rich High Strength Steel

    • 摘要: 在低碳高强钢中引入纳米富Cu析出相可以在保证其强韧性的同时,改善焊接性,但需要采用适当的热加工工艺来调控纳米强化相的析出行为。采用JMatPro软件、光学显微镜以及透射电镜等研究了热加工工艺对铁素体型富Cu纳米析出强化高强钢析出行为的影响。结果表明,热轧态铁素体型富Cu高强钢中析出相主要为直径约15 nm的球状(Nb,Ti)C,经过600℃回火后有大量尺寸为5~17 nm的细小9R/3R结构富Cu相弥散析出,并有少量尺寸为100~280 nm的大尺寸(Fe,Cr)3C析出。纳米富Cu强化相的强化增量可达约92 MPa,其与基体为半共格关系,对韧性无不利影响。因此,回火态的铁素体型富Cu高强钢的屈服强度可达639 MPa,-40℃冲击吸收功可达265 J,具有良好的强韧性匹配。

       

      Abstract: The introduction of nanoscale Cu-rich precipitates into low carbon high strength steel can improve the weldability while ensuring its strength and toughness, but the precipitation behavior of nanoscale Cu-rich precipitates need to be controlled by appropriate hot working process. The effect of hot working process on the precipitation behavior of ferritic Cu-rich nano-precipitation strengthened high strength steel was studied by JMatPro software, optical microscope(OM) and transmission electron microscope(TEM). The results show that the precipitates in hot-rolled ferritic Cu-rich high strength steel are mainly spherical(Nb,Ti)C with a diameter of about 15 nm. After tempering at 600 ℃, a large number of fine 9R/3R structure Cu rich phases dispersion of 5-17 nm, and a small amount of large(Fe,Cr)3C precipitate with a size of 100-280 nm.The strengthening increment of nanoscale Cu-rich phase is about 92 MPa, which is semi-coherent with the matrix and has no adverse effects on the toughness. Therefore, the yield strength of the tempered ferritic Cu-rich high strength steel can reach639 MPa and the impact absorption energy can reach 265 J at-40 ℃.

       

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