摘要
本文研究了由Ⅱ。组、65、65Mn 及50CrVA 钢丝制造的压缩螺旋弹簧的应力松弛性能、组织结构及其影响因素。试验结果表明:应力松弛过程可分为两个阶段,在半对数坐标中均为直线型,其通式为:(?),%=a+b (?)。这说明低温应力松弛属于对数蠕变,是回复、应变时效和动态回复的综合效应。第一阶段由回复起主导作用,位错组态和亚结构的变化比较显著,故松弛率较大;第二阶段主要由动态回复所控制,位错亚结构变得比较均匀稳定,故松弛率较小。采用热磁和电强压处理后,由于位错亚结构在较短时间内达到均匀稳定,故只出现松弛过程的第二阶段,从而显著提高了弹簧的抗应力松弛性能,使各种压缩螺旋弹簧的十年载荷损失效率(?)_(10)<5%。Ⅱ。和50CrVA 形变热处理钢丝弹簧的(?)_(10),%分别降低94%和92%。
In this paper,the stress relaxation ability,structural change and its in-
fluence factors of compression helical springs made of different steel wires
(group Ⅱa,65,65Mn and 50CrVA) are investigated.Experimental results show
that the stress relaxation process at lower temperature may bedivi ded into two stages and presented in linear equation as follows in general:(ΔP/P_0)_(10)=a+
blnt_R So,it is called logarithmic creep and is a combined effects of recovery,
strain aging(hardening)and dynamic recovery of steel wires.In the first stage
of stress relaxation,recovery of steels may play the leading role,the changes
of dislocation and substructure are comparatively remarkable,so the rate of
relaxation is larger.The second stage of that is mainly controlled by the dy-
uamic recovery,the dislocation structure will be changed into more homogeneo-
us and stable state,so the rate of relaxation smaller.Using the hot,magne-
tic or electric prestressing treatment of springs,the dislocational structures
may be transformed into relatively homogeneous and stable state in a shorter
time,so the second stage of the stress relaxation only appears,and it remark-
ablely improves the stress relaxation ability.The loss rate of the load(ΔP_0/P_0)_(10)
of compression helical springs is below 5% in 10 years.As compared with the
untreated springs,the (ΔP/P_0)_(10) of group Ⅱ.(hard cold drawn steel wire)
and 50CrVA (LTMT wire) springs may be reduced 94% and 92% respectively.
关键词
弹簧钢
应力反弛性能
强压处理
spring steels
stress relaxation ability
prestressing treatment
loss rate of load
substructure
