【摘要】 研究了20g材质老化程度对各种力学性能的影响,认为20g材质老化是从本质上影响延迟焦化焦炭塔安全运行的主要因素,应依据材质老化程度来判断焦炭塔是否报废。材质老化是一个复杂的过程,20g材质老化实质是具有较高表面能的片状珠光体在高温下向具有较低表面能的球状珠光体转化。焦炭塔在运行过程中产生腰鼓变形是不可避免的,其成因是塑性变形的累积。腰鼓变形有如下过程(规律性):在热应力作用下,焊缝热影响区局部发生屈服,这种屈服区域的不断扩大和累积则形成焦炭塔的腰鼓变形。对腰鼓变形问题的研究主要集中于确定腰鼓变形量的临界值,并以腰鼓变形量是否超过临界值作为焦炭塔判废的标准之一。更多还原

【Abstract】 The study on the aging of 20 steel material concludes that the aging of 20g steel is the major factor affecting safe coker drum operation. Therefore the coker drum should be invalidated based upon its extent of aging. Material aging is a complex process. The essence of 20g material aging is that the flaky pearlite with higher surface energy transforms to spherical pearlite with lower surface energy at high temperatures. The loin-drum deformation is unavoidable in coker drum operation, which is the result of accumulation of plastic deformation. It exhibits the following regularity: under the effect of heat stress, the local yield is produced in the heat affected zone of welds and then developed and accumulated, leading to the loin-drum deformation of the coker drum. One of criteria for coker drum invalidation is whether the loin-drum deformation has exceeded the critical value.更多还原