共查询到18条相似文献,搜索用时 187 毫秒
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《机械工程学报》2017,(8)
利用单道次、双道次热压缩试验研究铸态P91合金钢在热变形后的动态、静态、亚动态再结晶行为,探索不同变形温度、应变速率、变形量对静态、亚动态再结晶的影响并建立静态、亚动态再结晶动力学方程。研究得出:热变形结束后,静态再结晶率随变形温度、变形量及应变速率的增大而增大;亚动态再结晶率与变形温度、变形量和应变速率呈单调递增,并最终趋于稳定。以真应变为参数,铸态P91热变形后再结晶类型可按照真应变分为三种情况:当εε_c时,道次间隔主要发生静态再结晶;当ε_cεε_T时,同时发生静态、亚动态再结晶;当εε_T时,主要发生亚动态再结晶。通过对双道次压缩试样的显微组织分析得出:相同变形条件下,亚动态再结晶晶粒比静态再结晶细小,再结晶晶粒随变形温度增加而增大,随应变速率增大而减小。 相似文献
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选用Gleeble-3500型热模拟试验机在变形温度330~450℃、应变速率10-2~10 s-1、压缩变形量60%条件下对2219铝合金进行热压缩试验,研究了其在热变形过程中的动态再结晶行为;通过对试验数据进行分析拟合,建立了以Z参数表示的热变形特征参数模型,基于改进Avrami方程的动态再结晶动力学模型以及以变形温度、应变速率表示的再结晶晶粒尺寸模型.结果表明:在低应变速率和高变形温度下,2219铝合金更易于发生动态再结晶;根据动态再结晶动力学模型,最佳热加工条件为应变速率0.1 s-1、温度360℃,此时2219铝合金的动态再结晶程度最高;动态再结晶晶粒尺寸模型预测精度较高,线性相关系数达0.95. 相似文献
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在热模拟试验机上利用双道次压缩方法研究了E36高强度球扁钢在不同温度下两次变形弛豫的静态再结晶行为。结果表明:E36钢在900℃以上变形时,再结晶过程较快,在30~50 s内均已完成完全再结晶;在900℃时,再结晶过程明显减慢,弛豫1 000 s再结晶体积分数还不到50%,再结晶孕育期增至40 s左右;850℃时再结晶已非常困难,弛豫4 000 s后由于奥氏体静态再结晶数量多,最终组织拉长的贝氏体晶粒较驰豫1 000 s的少,大部分是由再结晶后等轴奥氏体晶粒转变而来的细小、均匀的贝氏体晶粒,沿晶界有较多针状铁素体晶粒。 相似文献
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The dynamic recrystallization as well as meta‐dynamic and static recrystallization of the nickel‐based alloy 80A was investigated by means of electron backscatter diffraction (EBSD). Specimens were hot compressed at a temperature of 1120°C and a strain rate of 0.1/s at varying strain and soak times to describe the recrystallization behaviour. Various approaches were tested in order to differentiate between recrystallized and deformed grains based on EBSD data. The grain orientation spread was clearly found to be the most reliable procedure. A high twinning of the recrystallized grains was observed, and as a consequence the measured grain size was strongly dependent on whether the coherent and incoherent twin boundaries were regarded as genuine boundaries or removed. 相似文献
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A. N. Stashkov V. M. Somova E. Yu. Sazhina L. A. Stashkova V. S. Nogin A. P. Nichipuruk 《Russian Journal of Nondestructive Testing》2013,49(12):705-714
The results of the measurements of the magnetic properties of plastically tensile-deformed samples of grade 08X15H5д2T maraging steel are represented. Preliminary the samples were subjected to annealing, quenching, and ageing with a variation in temperature and holding time for obtaining of the various initial contents of retained austenite. It was found that the testing of the content of retained austenite in the deformed state is possible by saturation induction B s . The use of the structural-sensitive parameter N′ (an analogue of the internal demagnetization factors) allows one to determine the content of retained austenite in the undeformed state and in the prerupture state and the qualitative separation of plastically deformed and undeformed products of grade BHC-2УШ steel. 相似文献
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J. Halling 《Wear》1982,76(2):263-266
The effect of cutting speed and tool wear land length on the plastic strain distribution in the surface region of annealed 18% Ni maraging steel machined under lubricated and unlubricated conditions is determined by using the grid technique.The results show that the magnitude of the plastic strains in the surface region and the depth of the plastically deformed layer increase with an increase in the cutting speed or the tool wear land length or both. The presence of the lubricant in the cutting region results in considerable reduction in the subsurface deformation. 相似文献
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基于Arrhenius改进模型的无取向电工钢高温变形本构关系 总被引:1,自引:0,他引:1
建立无取向电工钢热轧高温行为的统一本构关系模型。基于大型工业轧机取样的无取向电工钢连续冷却转变图分析测定,采用Gleeble热模拟试验机在750~1 120℃温度范围和0.05~10 s~(-1)应变速率范围进行热模拟试验。随着温度的降低,在1 120~975℃的奥氏体区,应力随之增加;975~875℃的奥氏体-铁素体两相区内,应力随之降低;875~750℃铁素体区内,应力随之增加;铁素体区以动态回复软化机制为主,而奥氏体区以动态再结晶为主,而且变形速率越大,动态再结晶越不明显,直至仅呈现动态回复型。基于Arrhenius改进模型框架,建立描述该钢种热连轧机粗轧机组和精轧机组完整轧制过程加工硬化与软化机制的统一本构关系,可精确地预测加工材料的属性。 相似文献
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利用MMS-200型热力模拟试验机研究了10B06冷镦钢连铸坯在750~1 100℃、应变速率为0.01~20s-1条件下的热压缩流变行为,并且通过线性回归确定了该钢的应变硬化指数以及热激活能,获得了其在变形条件下的流变应力本构方程。结果表明:该钢在热压缩变形时的流变软化行为是动态再结晶、动态回复与加工硬化联合作用的结果;当变形温度较低、应变速率较小时,软化效应以动态再结晶为主;而当变形温度较高、应变速率较大时,软化效应是动态再结晶和动态回复共同作用的结果;该钢的流变应力可采用Zener-Hollomon参数的函数来描述,其热激活能为220.132 3kJ.mol-1。 相似文献
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为了揭示动态再结晶行为的本质及其对流变应力的影响,选取904L奥氏体不锈钢为研究对象,针对奥氏体在不同工艺下的热变形行为以及变形组织和再结晶组织的亚结构进行深入研究。结果表明材料的宏观应力-应变曲线在特定条件下不能准确反映微观尺寸上的动态再结晶行为。EBSD分析表明动态再结晶晶粒中亚结构特征以取向差角小于1°为主,呈周期性分布,且这种特征不会随晶粒自身长大或应变的增加而发生明显改变,即具有较好的稳定性;而变形组织中亚结构的取向差角明显增大,频繁出现大于1°的小角晶界,局部取向差角的分布范围也增大至1°~4°,即几何必需位错密度显著增加。尽管无论何种工艺下晶界均为再结晶的优先形核位置,但形核条件是不同的。对于完全再结晶组织来说,新的再结晶晶粒形核只需晶界出现局部“弓出”或弯曲;而在原始变形组织中,出现再结晶形核的晶界均存在微区高应变。 相似文献