Wang Yu, Cao Heng, Lou Yanchun, Cao Lei, Gao Yunbao, Zhao Ling
State Key Laboratory of Advanced Casting Technologies, Shenyang 110022, China.
China Academy of Machinery Shenyang Research Institute of Foundry Co., Ltd., Shenyang 110022, China.
Materials (Basel). 2025 May 19;18(10):2364. doi: 10.3390/ma18102364.
This research focuses on Fe-18Mn-10Al-1C-5Ni lightweight steel and deeply explores the influences of three different cooling methods, namely, water quenching (WQ), air cooling (AQ), and furnace cooling (FQ), on the precipitation behavior of the B2 phases and κ-carbides in the lightweight steel. The intrinsic relationship among the precipitated phases, mechanical properties, and fracture behavior is revealed. Compared with the WQ sample, the size of the intragranular B2 phase in the AQ sample did not change significantly (an increment of 9 nm), but nano-sized κ-carbides appeared at the grain boundaries and inside the grains. The yield strength and tensile strength of the AQ sample significantly increased to 1232 MPa and 1347 MPa, respectively, while an elongation of 17.4% was still maintained, which benefitted from the synergistic effect of the grain boundary B2, intragranular B2, and nano-sized κ-carbides. When the cooling rate of the heat treatment was further reduced, the size of the intragranular B2 phase in the FQ sample increased slightly (332 nm), and the κ-carbides at the grain boundaries became obviously coarsened (170 nm), resulting in a severe reduction in the elongation (2.3%) because, during the tensile deformation process, the coarsened κ-carbides at the grain boundaries promoted the nucleation of voids and microcracks. The present work provides new insights into the cooling heat treatment process of lightweight steel.
本研究聚焦于Fe-18Mn-10Al-1C-5Ni轻质钢，深入探究了三种不同冷却方式，即水淬（WQ）、空冷（AQ）和炉冷（FQ），对轻质钢中B2相和κ-碳化物析出行为的影响。揭示了析出相、力学性能和断裂行为之间的内在关系。与水淬样品相比，空冷样品中晶内B2相的尺寸变化不显著（增加了9nm），但在晶界和晶粒内部出现了纳米尺寸的κ-碳化物。空冷样品的屈服强度和抗拉强度分别显著提高到1232MPa和1347MPa，同时仍保持伸长率为17.4%，这得益于晶界B2、晶内B2和纳米尺寸κ-碳化物的协同作用。当进一步降低热处理的冷却速率时，炉冷样品中晶内B2相的尺寸略有增加（332nm），晶界处的κ-碳化物明显粗化（170nm），导致伸长率严重降低（2.3%），因为在拉伸变形过程中，晶界处粗化的κ-碳化物促进了空洞和微裂纹的形核。本研究为轻质钢的冷却热处理工艺提供了新的见解。
