淬火20CrNi2Mo低碳钢中大角度晶界对强度的影响

Effect of the High Angle Boundaries on Strength for 20CrNi2Mo Steel

中文关键词: 20CrNi2Mo钢 马氏体 多层次结构 大角度晶界 有效控制单元

英文关键词: 20CrNi2Mo steel, martensite, multi-level microstructure, high angle boundaries, effective control unit

中文摘要:

      采用OM、SEM、EBSD和TEM对20CrNi2Mo钢的微观组织进行定量表征,同时讨论了位错强化(σ_d)、固溶强化(σ_ss)、析出强化(σ_d)和晶界强化(σ_g) 对试验钢强度的贡献,且利用经典的Hall-Petch关系分析了强度的有效控制单元。结果表明:随淬火温度的升高,试验钢的原奥氏体晶粒(d_r)和马氏体束(d₀)、块(d_b)等均增大,马氏体板条略微细化。同时,试验钢的强度随淬火温度的升高而降低,塑性增加；量化的四种强化方式中σ_d、σ_ss 基本不变,σ_d忽略不计,试验钢的强度变化主要取决于σ_g。此外,试验钢的强度与多层次组织间的Hall-Petch关系揭示了块是强度的有效控制单元。

英文摘要:

      The micro-structures for 20CrNi2Mo were characterized quantitatively by OM, SEM, EBSD and TEM, and the contribution of strength was discussed from four strengthening mechanisms, e.g. dislocations hardening (σ_d), solid solution hardening (σ_ss), precipitation hardening (σ_p) and grain boundary strengthening (σ_g). Subsequently, the Hall-Petch equation was used to determine the effective control unit of strength. The results showed that prior austenite grain (dr), packet (dp) and block (db) increased with the increasing of quenching temperature while the martensite lath decreased. Meanwhile, as the increasing of quenching tempe-rature, the strength of tested steel increased and the plasticity decreased. The increasing of strength was determined by σ_g or the common role for dr, dp and db, namely the dislocation was hindered from the high angle boundaries. The contribution of σ_d and σ_ss remained and σ_d was ignored. In addition, the martensite was the effective control unit of strength from the Hall-Petch relationship.