【作者】 高伟；

【导师】 任运来；

【作者基本信息】 燕山大学 ， 材料加工工程， 2011， 硕士

【摘要】 核电用蒸发器的传热管是急需国产化的重要零部件之一。本文以实验研究为主,对304LN不锈钢的高温变形行为、热加工图以及管材热挤压数值模拟进行了分析和研究,并通过对比模拟实验,以得到适宜的加工工艺参数。文章通过等温、等应变速率热压缩实验,研究了304LN不锈钢的高温变形行为,可以看出该不锈钢是对温度和应变速率比较敏感的材料。通过真实应力应变曲线观察到不锈钢在高温变形过程中出现了动态软化现象,经过理论分析,可以认为其软化发生的机制主要是因为发生了动态再结晶。通过引入Zener-Hollomon参数,根据Gleeble试验得到的真实应力应变数据,可以建立304LN的本构方程,并得到公式中对应的热变形激活能Q和其他相关材料参数。利用Prasad等人提出的热加工图理论,根据动态材料模型为基础构建出了304LN不锈钢的热加工图,确定在Gleeble实验数据选取的参数范围内,304LN不锈钢最适的热加工参数范围以及应该避免的热加工过程中出现失稳等缺陷的范围。文章利用刚塑性有限元软件Deform-3D,对不锈钢管材的热挤压过程进行刚塑性热力耦合模拟,根据挤压时材料塑性变形区域的温度和应变速率,是否处于热加工图中的安全加工区域,来判断所选参数是否符合热挤压工艺,并通过不同挤压比和挤压速度的对比,给出该材料加工时最适的加工工艺参数。更多还原

【Abstract】 Steam Generator heat-transfer tube in PWR power station are one of the most important components of domestic which are in urgent need. In this dissertation, mainly basing on experimental research,the hot workablity of 304LN stainless steel,such as ,high temperature deformation behavior, thermal processing map and simulation of tube extrusion were analyzed and studied, And through comparing the simulation experiment, to get the suitable processing parameters.In the dissertation,through by isothermal and equal-strain rate hot compression experiments,we get the deformation behavior on high temperature,and found the 304LN stainless steel is sensitive to temperature and strain rate.During the high temperature deformation process,we can find the dynamic softening by the true stress-strain curve. Through theoretical analysis, the mechanism of softening occurs mainly due to dynamic recrystallization occurred.The establishment of 304LN stainless steel constitutive equation is set up with Zener-Hollomon parameter , the hot deformation activation energy Q and the related material parameters are get.According to the processing map theory given by Prasad, the establishment of the 304LN stainless steel processing maps is based on the dynamic material model. In the parameters scope of Gleeble experiments get from,determine the 304LN stainless steel thermal processing parameters of the optimal range and should be avoided range of the parameters.In the dissertation,we use finite element software Deform to do simulation of the pipe extrusion,based on the rigid-plastic coupled thermo-mechanical FEM theory. According to the plastic deformation area of the temperature and strain rate, whether in the security area of processing map to judge whether the selected parameters accord with the hot extrusion process. Through different extrusion ratio and extrusion speed contrastand ,gives the material processing optimal parameters required for processing.更多还原