Effect of niobium and titanium addition on the hot ductility of boron containing steel
Effect of niobium and titanium addition on the hot ductility of boron containing steel
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DOI：
10.1016/j.msea.2011.01.097
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发表时间：
2011-04
期刊：
影响因子：
6.4
通讯作者：
K. Cho;D. Mun;Y. Koo;Jae Sang Lee
中科院分区：
文献类型：
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作者：
K. Cho;D. Mun;Y. Koo;Jae Sang Lee
使用热拉伸试验对添加 Nb (0.03wt.%) 的含硼钢（B 钢）（B-Nb 钢）和添加 Ti（0.0079wt.%）的 B-Nb 钢（B-Nb-Ti 钢）的热延展性进行量化。试样在1350°C下进行固溶处理，并在20°Cs−1下冷却至拉伸试验温度（T），范围为750≤T≤1050°C。之后，它们以 2.5×10−3s−1 的应变速率应变至失效。对于B-Nb钢，在850≤T≤950℃时观察到严重的热塑性损失，该温度涵盖了奥氏体（γ）单相存在的低温以及γ和铁素体（α）共存的高温。 B-Nb 钢的延展性损失是由 BN 析出物网络的存在引起的，而不是由 γ 晶界处的 Nb(C, N) 析出物引起的。相比之下，B-Nb-Ti钢的热塑性在850≤T≤950℃下显着提高。在B-Nb-Ti钢中，BN优先在TiN颗粒上析出，导致γ晶粒内部BN析出增多，而γ晶界处BN析出网络减少。这些变化减少了 γ 晶界处的应变局部化，从而提高了钢的热延展性。
Hot ductility of boron containing steel (B steel) with adding Nb (0.03wt.%) (B–Nb steel) and B–Nb steel with adding Ti (0.0079wt.%) (B–Nb–Ti steel) was quantified using hot tensile tests. The specimens were solution-treated at 1350°C and cooled at 20°Cs−1to tensile test temperature (T) in the range of 750≤T≤1050°C. After that, they were strained to failure at a strain rate of 2.5×10−3s−1. For the B–Nb steel, severe hot ductility loss was observed at 850≤T≤950°C, which covered the low temperature in which austenite (γ) single-phase exists, and the high temperature at which γ and ferrite (α) coexist. Ductility loss in the B–Nb steel was caused by the presence of a network of BN precipitates, rather than by Nb(C, N) precipitates at the γ grain boundaries. In contrast, hot ductility of the B–Nb–Ti steel was remarkably improved at 850≤T≤950°C. In the B–Nb–Ti steel, BN precipitates preferentially on TiN particles, resulting in increased BN precipitation in the γ grain interior and a decrease in the network of BN precipitates at the γ grain boundaries. These changes reduce strain localization at the γ grain boundaries and therefore increase the hot ductility of the steel.