At lower annealing temperature obtain high strength and high yield ratio showed cyclic softening feature easily. That is detrimental to the using life of coiled tubing.
较低退火温度获得高强度、高屈强比易表现出循环软化特征，不利于提高连续油管的疲劳寿命。
2
Then, a logic computational diagram is constructed for calculating diametral growth by assuming fatigue cyclic softening, namely yieldstrength reduction as tubing fatigues.