CAJ | 학술논문

通过研究变形过程和变形间隔时间内的位错密度变化规律，提出用变形前的初始位错密度来表示残余应变的大小。在Gleeble-3500热模拟试验机上对X70管线钢进行双道次压缩试验，对试验数据进行回归拟合得到位错密度模型参数。计算不同变形间隔时间下的初始位错密度，并结合变形抗力模型计算变形抗力。变形抗力的计算值和实测值有较好的一致性，表明可以用该模型来表示残余应变对变形抗力的影响。对不同的变形间隔时间，静态回复和静态再结晶对位错密度的影响程度不同。变形间隔时间短时，静态回复过程占主导，在计算残余应变时必须考虑静态回复过程对位错密度的影响；变形间隔时间长时，可以只考虑静态再结晶过程对位错密度的影响。该模型基于残余应变产生的微观机理，较传统残余应变模型的使用范围更广，计算精度更高。
통과연구변형과정화변형간격시간내적위착밀도변화규률，제출용변형전적초시위착밀도래표시잔여응변적대소。재Gleeble-3500열모의시험궤상대X70관선강진행쌍도차압축시험，대시험수거진행회귀의합득도위착밀도모형삼수。계산불동변형간격시간하적초시위착밀도，병결합변형항력모형계산변형항력。변형항력적계산치화실측치유교호적일치성，표명가이용해모형래표시잔여응변대변형항력적영향。대불동적변형간격시간，정태회복화정태재결정대위착밀도적영향정도불동。변형간격시간단시，정태회복과정점주도，재계산잔여응변시필수고필정태회복과정대위착밀도적영향；변형간격시간장시，가이지고필정태재결정과정대위착밀도적영향。해모형기우잔여응변산생적미관궤리，교전통잔여응변모형적사용범위경엄，계산정도경고。
Based on the dislocation density changes during deformation and deformation interval, a method of using the initial dislocation density before the deformation to describe residual strain is proposed. Double-hit compression tests are performed in X70 pipeline steel on a Gleeble-3500 thermomechanical simulator. Parameters of dislocation density model are obtained after the test data regression. The initial dislocation density after different time interval is calculated. The deformation resistance is also calculated from deformation resistance model. The good agreement between the predicted values of deformation resistance and experimental results indicates the validation of the computational method. As static recovery is dominant when the interval time is short, it is necessary to take the static recovery into account when calculating residual strain. It can only take static recrystallization into consideration when the interval is long. The method of this study is based on the formation mechanism of residual strain. It has a wider range of application and a better precision of calculation comparing with the traditional methods.