LI Da-zhao
,
WEI Ying-hui
,
HOU Li-feng
,
LIN Wan-ming
钢铁研究学报(英文版)
A nanocrystalline layer was synthesized on the surface of TWIP steel samples by surface mechanical attrition treatment (SMAT) under varying durations. Microhardness variation was examined along the depth of the deformation layer. Microstructural characteristics of the surface at the TWIP steel SMATed for 90 min were observed and analyzed by optical microscope, X-ray diffraction, transmission and high-resolution electron microscope. The results show that the orientation of austenite grains weakens, and α-martensite transformation occurs during SMAT. During the process of SMAT, the deformation twins generate and divide the austenite grains firstly; then α-martensite transformation occurs beside and between the twin bundles; after that the martensite and austenite grains rotate to accommodate deformation, and the orientations of martensite and between martensite and residual austenite increase; lastly the randomly oriented and uniform-sized nanocrystalline layers are formed under continuous deformation.
关键词:
SMAT technology
,
twinning
,
stacking fault energy
,
deformation twin
杨泽斌
,
朱定一
,
易炜发
,
林淑梅
钢铁
采用单向拉伸、金相组织观察、TEM等方法，研究了3种不同碳含量Fe-Ni-Mn-Si-C系TWIP钢的拉伸应变硬化行为。研究结果表明，随着碳含量的增加，合金的强度和伸长率均提高，当碳质量分数为1.0%时，该TWIP钢具有较好的综合力学性能，强塑积达到83160MPa·%。3种TWIP钢的真应力-真应变曲线均不完全遵循Hollomon的线性关系。在低应变阶段，碳含量高的合金应变硬化指数略低于碳含量低的合金。而在高应变阶段，n值随碳含量的增加而增大并维持于一定值。该类TWIP钢的微观变形机制是: 当真应变ε<0.12时，位错滑移为主要的变形机制；当0.12<ε<0.42时，强化机制以应变诱发孪晶为主。碳含量的增加，推迟了形变孪晶的产生，延长了应变硬化行为的第2阶段，提高了合金的强度与韧性。
关键词:
TWIP钢
,
carbon content
,
mechanical property
,
strain hardening
,
deformation twin
