刘东升
,
王国栋
,
刘相华
,
甄立冬
,
苏永科
,
徐辉
金属学报
采用膨胀法结合金相分析建立了P20钢的CCT曲线,根据动态CCT曲线，提出P20钢轧后控冷预硬化工艺．与常规热处理条件相比，形变热处理条件下的奥氏体具有较高的稳定性.变形后以0．2—0．02℃／s连续冷却时，主要发生贝氏体相交，而多边形铁素体相变被抑制．变形可使奥氏体机械稳定化，阿氏体相变推迟至较低温度下完成.P20钢轧后在贝氏体相变区缓冷获得粒状贝氏体组织，实现在线预硬化，硬度达到35—38．
关键词:
P20塑料模具钢
,
hardening
,
transformation
,
granular bainite
,
deformed austenite
L. W. Zhang
,
J. Th.M.De Hosson
,
Y.L. Xia and F. G. Wang 1)The State Key Lab. for Materials Modification by Laser
,
Ion and Beams
,
Dalian University of Technology
,
Dalian 116023
,
China 2)Department of Applied Physics
,
University of Froningen
,
The Netherlands
金属学报(英文版)
In this paper,a thermal elastic-plastic 2-D finite element model of stress generation during laser transformation hardening process was developed. In this model, the mechanical properties of the material, Young's modules E, Poisson's ratio v, yield limit s, and thermal expansion coefficient α, are all change with temperature. The equivalent expansion method was used to deal with the problem with phase transformation. Based on this model, a program to calculate the residual stress field was developed using FORTRAN language. The residual stress fields in CO2 laser transformation hardened MoCu nodular iron were calculated. The calculated results showed that in the transformation hardened zone, the residual stress state is compress,whereas adjacent to this zone the residual stress state is tensile, and there is a tensile stress peak close to the transformation hardened zone. To verify this model, the residual stress fields were measured using X-ray diffraction method. The calculated results of residual stress fields are in good agreement with the experimental results.
关键词:
laser
,
null
,
null
,
null
,
null
刘海平
,
刘伟东
,
屈华
,
刘斯琦
稀有金属材料与工程
计算了TiB与TiB2的价电子结构,研究了TiB、TiB2的价电子结构与TC4合金渗硼层硬化的关系.研究发现:TC4合金渗硼层的TiB2和TiB相中B-B原子键合力最强,且远大于合金基体组成原子的键合力;TiB2相最强共价键的共价电子对数nTiB2A为0.5554,TiB相最强共价键的共价电子对数nATiB2为0.4042,因此TiB2相对基体的硬化作用更强;TiB2相的原子状态组数σN为123,而TiB相的原子状态组数σN为19,所以TiB2相的稳定性更高;由相成键能力F的计算可知,从热力学角度看,渗层中TiB应比TiB2多;共价键空间分布决定了TiB晶体易沿[010]晶向生长成短纤维状,而TiB2相易于生成高对称性的粒状或球状,故TiB2比TiB更有利于硬化基体.
关键词:
TC4合金
,
渗硼层
,
TiB
,
TiB2
,
价电子结构
,
硬化
袁军平
,
李桂双
,
陈德东
,
马春宇
,
王昶
材料热处理学报
传统足金的硬度很低,制约了首饰的艺术价值.采用钴、锑、钪对纯金进行微合金化处理,研究了改性足金的显微组织和硬化行为.试验结果表明,改性足金(含金量99.31 mass％)的铸态硬度可达到62 HV,经700℃固溶处理后组织呈现单一固溶体结构,硬度可达到51 HV.固溶态材料经冷变形处理时,形变量为80％时硬度达到121 HV,再经250℃时效处理后出现了弥散分布的沉淀析出相,晶粒组织比传统足金显著细化,硬度达到了138 HV.改性足金的硬化行为是合金元素固溶强化、细晶强化、形变强化和析出强化综合作用的结果.
关键词:
足金
,
微合金化
,
硬化
