摘要
通过SEM、TEM和XRD等手段,研究了含铜9Ni钢两相区热处理(QLT)中加热温度(TL)、及回火温度(TT)对组织的演化、回转奥氏体含量以及力学性能的影响。结果表明:回转奥氏体主要在马氏体板条间析出,随着TL的升高,奥氏体形态从点状、块状转变为棒状。当TL为600℃时,获得5.6%但稳定的回转奥氏体;而当TL为较高的670℃时,回转奥氏体含量为12.3%但欠稳定。同时,高温回火下能获得数量较多且稳定的回转奥氏体,有利于得到较好的深冷冲击韧性;纳米级含Cu沉淀相主要在位错、晶界和基体中析出,随着TL的升高,沉淀相逐渐粗化,沉淀强化效果减弱.含铜9Ni钢经过两相区淬火回火处理,其在-196℃下的最佳Charpy冲击功为143 J,抗拉强度达到802 MPa。较小的性能差异体现了9Ni-Cu材料具有较宽的两相区热处理工艺窗口。
The effect of reheating temperatures at dual phase region （ TL） and tempering temperatures （ TT ） of the heat treatment （Quenching, Lamellarizing and Tempering, QLT） on fraction of reversed austenite and microstructure in Cu bearing 9% Ni steel was investigated by means of SEM,TEM and XRD. The dependence of mechanical properties,especially the cryogenic toughness upon the TL, and Tr was also evaluated. The results show that austenite phase is found to precipitate predominantly between the martensite laths,and the morphology changes from dots to rods as the TL increasing. When the TL, is 600 ℃ ,the fraction of reversed austenite is 5.6% , however, with high thermal stability. On the other hand,when the TL, is 670℃ ,the fraction of reversed austenite is 12.3% with decreased stability. Tempering at high temperatures promotes the precipitation of austenite with considerably high stability and fractions, which benefits the cryogenic toughness at - 196 ℃. Copper bearing particles in nanometer scale mainly precipitate at dislocations,grain boundaries and also in the matrix. With the increasing of TL,the particles are coarsened which decreases the precipitation-strengthening,however, enhances the cryogenic toughness of the steel. The copper bearing 9Ni steel treated by the QLT exhibits cryogenic Charpy impact energy of 143 J and ultimate tensile strength of 802 MPa. Negligible fluctuation in tensile properties and cryogenic toughness is observed as the TL changes in the dual-phase region indicating that a robust QLT heat treatment is applicable for the copper bearing 9Ni steel.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2013年第1期132-138,共7页
Transactions of Materials and Heat Treatment
关键词
含铜9Ni钢
回转奥氏体
沉淀析出
回火温度
冲击韧性
copper bearing 9Ni steel
reversed austenite
precipitation
tempering temperature
toughness
