A STRESS-RELAXATION METHOD FOR FOLLOWING CARBONITRIDE PRECIPITATION IN AUSTENITE AT HOT-WORKING TEMPERATURES
A STRESS-RELAXATION METHOD FOR FOLLOWING CARBONITRIDE PRECIPITATION IN AUSTENITE AT HOT-WORKING TEMPERATURES
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DOI：
10.1007/bf02674014
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发表时间：
1988-06-01
期刊：
影响因子：
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通讯作者：
JONAS, JJ
中科院分区：
文献类型：
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作者：
LIU, WJ;JONAS, JJ
在850至1050 °C的温度范围内对一种普通碳钢和四种固溶处理的Ti钢进行应力松弛测量。结果表明，在5%的预应变（即，无沉淀时）可用关系式σ = σ0-α ln（l + βt）描述。相比之下，在固溶处理的Ti钢中，弛豫在沉淀开始时被阻止，并且在沉淀完成时被恢复。因此，这种机械方法特别适合于在热加工温度下在微合金化奥氏体中进行碳氮化物沉淀。本文提出了一个新的关于沉淀对位错运动影响的模型，并在此基础上阐明了应力松弛技术的唯象性。测定了含0.05、0.11、0.18和0.25%Ti的含Ti钢的结晶-时间-温度（PTT）图。所有钢的PTT曲线均呈C形。随着Ti和C浓度的降低，这些曲线的上部移动到显著更长的时间。相反，曲线的下臂的位置与所测试的钢的成分相对无关。
Stress relaxation measurements were carried out on a plain carbon and four solution-treated Ti steels over the temperature range 850 to 1050 °C. The results show that the stress relaxation of plain carbon austenite after a 5 pct prestrain (i.e., in the absence of precipitation) can be described by the relation σ = σ0-α ln(l + βt). By contrast, in the solution-treated Ti steels, relaxation is arrested at the start of precipitation and is resumed when precipitation is completed. As a result, this mechanical method is particularly suitable for following carbonitride precipitation in microalloyed austenite at hot working temperatures. A new model regarding the effect of precipitation on dislocation motion is proposed, on the basis of which, the phenomenology of the stress relaxation technique is clarified. Precipitation-time-temperature (PTT) diagrams were determined for the Ti bearing steels containing 0.05, 0.11, 0.18, and 0.25 pct Ti. The PTT curves obtained are C-shaped for all the steels. The upper parts of these curves are shifted to significantly longer times as the Ti and C concentrations are reduced. By contrast, the positions of the lower arms of the curves are relatively independent of the compositions of the steels tested.