张柯许为宗郭正洪戎咏华王毛球董瀚
金属学报
doi:10.3724/SP.J.1037.2010.00547
对比新型淬火-分配-回火(Q-P-T)和传统淬火-回火(Q-T)处理对中、低碳钢力学性能的影响发现, 在提高材料的强塑积方面 Q-P-T处理远胜于Q--T处理, 特别是对中碳钢的效果更为显著. 在所研究的试样中, Fe-0.42C-1.46Mn-1.58Si-0.028Nb合金的强塑积经Q-P-T处理后高达31627 MPa?%, 且延伸率达20.3%, 不仅远高于传统Q-T处理的试样, 而且已满足新一代先进高强度钢预测的性能. 显微组织分析表明, Q-T和Q-P-T处理的差异在于残留奥氏体的量和尺寸分布以及马氏体板条的均匀程度. 前者含少量 (<3%) 较薄的“薄膜状”残留奥氏体, 且马氏体板条尺寸范围较宽; 而后者含较多较厚的“薄片状”残留奥氏体, 且马氏体板条尺寸分布较窄. 因此Q-P-T处理的先进高强度钢具有承受较强的塑性变形和阻止微裂纹扩展的能力.
关键词:
Q-P-T工艺
,
advanced high strength steel
,
retained austenite
,
product of strength and elongation
王颖
,
张柯
,
郭正洪
,
陈乃录
,
戎咏华
金属学报
doi:10.3724/SP.J.1037.2012.00042
低碳Fe-0.25C-1.48Mn-1.20Si-1.51Ni-0.05Nb (质量分数, %) 钢通过新型Q-P-T工艺处理后获得高的抗拉强度和良好延伸率的综合性能. 对该低碳Q-P-T钢在拉伸过程中残余奥氏体含量的XRD 测定和形变孪晶马氏体的TEM观测, 证明了相变诱发塑性(TRIP) 效应的存在. 基于形变过程中马氏体和残余奥氏体中的平均位错密度测定和 TEM的观察, 验证了在中碳钢中最新发现的残余奥氏体吸收位错(DARA) 新效应在低碳钢中同样存在, 由此提出了DARA效应产生的条件, 阐明了残余奥氏体增强高强度钢塑性的机制.
关键词:
高强度钢
,
quenching-partitioning-tempering (Q-P-T) process
,
average dislocation density
,
retained austenite
,
effect of dislocation absorption by retained austenite (DARA)
任勇强谢振家尚成嘉
金属学报
doi:10.3724/SP.J.1037.2012.00210
采用完全淬火+两相区再加热-淬火-分配(IQ$\&$P)热处理工艺对0.23C-1.8Mn-1.35Si钢进行处理, 获得了具有亚温铁素体、马氏体以及广泛分布于原奥氏体晶界、相界等处的残余奥氏体等构成的多相组织. 利用SEM, XRD以及EBSD等对不同热处理阶段钢的微观组织进行了表征. 结果证实, 该多相组织低合金钢中残余奥氏体的获得主要依赖于以下两点: 一是两相区再加热阶段逆转变奥氏体组织中的富Mn富C, 二是淬火--分配阶段残留奥氏体在分配过程中的二次富C, 通过上述的两步元素富集处理可以使该低碳钢在室温下获得超过10%含量的残余奥氏体, 而残留奥氏体在分配过程中的二次富C则对该类钢中残余奥氏体的形成及其在室温下的稳定化起到了至关重要的作用. 由于广为分布的残余奥氏体在形变过程中的TRIP效应, 使得该类钢种在拉伸变形过程中获得了持续的加工硬化能力, 从而实现了强度与塑性的良好结合. 测试结果表明, IQ&P钢的强塑积超过了26 GPa?%, 屈服强度大于600 MPa, 抗拉强度超过900 MPa, 均匀延伸在16\%以上, 常温半厚冲击韧性达到了39 J.
关键词:
低碳钢
,
retained austenite
,
martensite
,
intercritical ferrite
,
TRIP effect
杨福宝
,
白秉哲
,
刘东雨
,
常开地
,
韦东远
,
方鸿生
金属学报
阐述了新型Mn--Si--Cr系无碳化物贝氏体/马氏体(CFB/M)复相钢的组织与合金设计思想；研究了复相钢在空冷条件下的组织及其精细结构, 并系统地总结了实验钢经不同温度回火后的力学性能. 实验结果表明, 复相高强钢在具有优良的强韧性能的同时, 又具有较高的延迟断裂抗力和抗疲劳破坏能力, 其强韧性的提高归于其独特的组织结构：贝氏体碳化物被薄膜状残余奥氏体所取代, 大大改善了复相钢的回火稳定性和疲劳性能, 稳定的残余奥氏体薄膜作为不可逆氢陷阱, 并显著提高了钢的抗氢脆能力.
关键词:
无碳化物贝氏体
,
duplex steel
,
retained austenite
JING Xiaotian LOU Bingzhe GU Chenqing SHEN Fusan Shanxi Institute of Mechanical Engineering
,
Xi'an
,
China Dept.of Materials
,
Shanxi Institute of Mechanical Engineering
,
Xi'an 710048
,
China
金属学报(英文版)
The morphology of the retained austenite in the carburized case of 20CrNiMo steel and its transformation during fatigue crack propagation through the case were investigated by using X-ray and TEM analysis.In the carburized case both film and block shaped retained austenite were found.Due to the crystallographic orientation relationship at the interface,the fatigue crack is inclined to pass through the block shaped retained austenite and thereby stim- ulates its strain-induced martensitie transformation.During the process of the fatigue frac- ture,most of the retained austenite structures on the crack path are transformed into the martensite,and the untranaformed parts on the fracture surface remain less than 6%.The transformation of the retained austenite,which is restrieted mainly within the plastic zone,oc- curs only during the proeess of fracture,and is independent of the magnitudes of the external stress,stress ratio and cyclic number.The volume expansion accompanying the transforma- tion creates an additional residual displacement of about 0.44μm on fracture surfaces,which is equivalent to the magnitude of the plasticity-induced residual displacement.The phase transformation induced fatigue crack closure is believed to be an important factor affecting the fatigue crack behaviors in the high carbon laver of the carburized case.
关键词:
retained austenite
,
null
,
null
,
null
S. Fedosov (Samara State Technical University
,
Galaktionovskaya 141
,
Samara 443010
,
Russia)
金属学报(英文版)
This paper Presents experimental data on effect of carbon concentration and laser processing regimes on retained austenite quantity. The data on retained austenite decomposition during subsequent temperings at various temperatures as well as after holding at room temperature during 3 years are given.Correla- tion between structural broadening of the X - ray lines of retained gamma - phase and the amount of the latter has been discovered.Mechanisms responsible for the increased quantity of the retained austen- ite in carbon and low alloyed steels after laser hardening are described.
关键词:
retained austenite
,
null
,
null
,
null
