本报告介绍了从炼油设备中取出的554个碳和碳钼钢试样的试验结果，并对其进行了石墨化证据检查。在这些样本中，有33.8%的样本中发现了石墨。 已经证实，一些钢比其他钢具有更大的石墨化倾向；铝含量高（超过0.015%）、工作温度高，以及为满足某些规格而采用的炼钢工艺，都是影响石墨化的因素。在所检查的钢材中，ASTM A I06管道显示出最高的石墨化倾向；在碳钢中，ASTMA 285板材的抗石墨化性能最高。碳素钢和碳钼钢中都发现了连接的石墨结节。 虽然碳钼钢的石墨化频率低于碳钢，但当它石墨化时，石墨化的类型更严重。 在1025°F的温度下，连续1000小时进行加速实验室试验，以预测在使用条件下钢的石墨化。这些试验表明，在使用中不发生石墨化的钢不一定对石墨化免疫。试验还表明，铝含量高的普通碳钢的某些“热处理”在整个50000小时的使用寿命内，以及在1025°F的温度下进行3000小时的加速试验后，都能抵抗石墨化。目前尚不清楚为什么有些钢的石墨化倾向如此之小。 此外，迄今为止开发的数据未显示任何可能表明取样压力设备不安全的情况。 目前正在石墨化钢板上进行的一系列应力断裂试验可以更准确地评估石墨化对焊接钢高温性能的影响。

This report presents the results of tests conducted on 554 specimens of carbon and carbon-molybdenum steel removed from petroleum refining equipment and examined for evidences of graphitization. Graphite formations were found in 33.8 per cent of these specimens. It has been established that some steels have a greater tendency to graphitize than others; and that high aluminum content (in excess of 0.015 per cent), high operating temperatures, and the steel-making process used in meeting certain specifications are factors which affect graphitization. Of the steels examined, ASTM A I06 pipe indicated the highest tendency to graphitize; and, of the carbon steels, ASTMA 285 plate material indicated the highest resistance to graphitization. Connected nodules of graphite were found in both carbon and carbon-molybdenum steels. Although the carbon-molybdenum steel graphitized less frequently than the carbon steel, when it did graphitize, graphitization was of the more serious type. At a temperature of 1025°F accelerated laboratory tests were made at successive 1,000-hour periods to predict the graphitization of steel under service conditions. These tests showed that a steel which does not graphitize in service is not necessarily immune to graphitization. The tests also indicate that certain "heats" of plain-carbon steel, with a high aluminum content, resisted graphitization throughout 50,000 hours of service life, as well as after 3,000-hour accelerated test periods at a temperature of 1025°F. It is not understood why some steels exhibit so little tendency to graphitize. Furthermore, the data developed to date do not reveal any condition which would indicate that the sampled pressure equipment is unsafe for further service. The series of stress-rupture tests now being conducted on graphitized plate may provide a more exact evaluation of the effect of graphitization on the high-temperature properties of welded steel.