X80级钢管热弯及热处理工艺参数的确定

Determination of the Hot Bending and Heat Treatment Process Parameters for X80 Grade Steel Pipes

评价了热弯及热处理热循环对X80级钢管力学性能的影响,研究了热弯过程中最佳加热温度和冷却速率及最佳热处理参数。首先,对来自不同炉批的2根钢管进行了工业化热弯及热处理试验。然后,对钢管试样进行实验室热处理试验。试样分别加热到900～1000℃,并以不同速率冷却,500℃下保温1h进行回火热处理。试验结果表明,加热到900～1000℃热弯,水淬并回火(500℃,1h)可获得较高的屈服强度。然而,实验室条件下试验所达到的冷却速率在工业化生产中较难实现。对于回火热处理试验,当回火热处理温度为600～650℃时,可获得最佳的屈服强度。基于实验室试验结果,采用600～650℃的回火温度是感应加热弯曲工艺生产X80级弯管的最佳选择。

The effect of hot bending and heat treatment thermal cycles on the mechanical properties of X80 grade steel pipe was evaluated. This study sought to define the best process temperatures and cooling rate during pipe bending, as well as optimized heat treatment parameters. Firstly,the pipe bending and the heat treatment were performed under industrial scale in two pipes from different heats. Subsequently, heat treatment was performed under laboratory scale on samples of the pipe. The pipe specimens were separately heated to between 900℃ and 1 030℃ ,and then at different cooling rate,tempered at 500 ℃ for 1 hour. Tests results showed heating specimen between 900 ℃ and 1000 ℃ followed by water quenching and tempering（500 ℃/1 h）was shown suitable to achieve a high yield strength level. However, the cooling rate obtained in these tests was very difficult to do under the industrial scale. Regarding tempering tests,the best values of yield strength were achieved for tempering between 600℃ and 650 ℃. Based on laboratory results, the 600℃ to 650℃ tempering temperature was shown to be the best option for the induction heated hot bending process of API 5L X80 grade bend pipes.