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利用透射电镜(TEM)、扫描电镜(SEM)等试验方法,研究了新型低成本HB450低合金超高强耐磨钢在不同回火条件下组织和性能演变规律,并分析了其强韧变化机制。结果表明:回火对试验钢的硬度和强度均有较大影响。在200~250℃回火,试验钢表现出良好的强韧性配合,满足国标工程机械用高强度耐磨板GB/T24186—2009中NM450级别要求;在250℃回火时,试验钢出现硬化迹象。透射电镜分析表明,在该温度下回火,析出物中除了有大量弥散分布的ε-碳化物外,还出现了少量30~50 nm的(Nb,Ti)(C,N)粒子,该2类粒子对试验钢的强化起着较大的作用。
The microstructure and properties of new low cost HB450 low alloy ultrahigh strength steel with different tempering conditions were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The mechanism of strength and toughness was also analyzed. The results show that tempering has a great influence on the hardness and strength of the test steel. Tempering at 200 ~ 250 ℃, the test steel showed good strength and toughness to meet the national standard of construction machinery with high strength wear plate GB / T24186-2009 NM450 level requirements; tempering at 250 ℃, the test steel showed signs of hardening . Transmission electron microscopy analysis showed that a small amount of (Nb, Ti) (C, N) particles of 30 ~ 50 nm appeared in addition to a large amount of ε-carbides dispersed in the precipitate at tempering at this temperature. Particles on the strengthening of the test steel plays a larger role.