对在役运行５ａ后加氢反应器中的试验试块进行研究，评定了试验试块焊缝金属的回火脆性。同时对脱氢处理和脱脆处理后的焊缝金属进行了试验，试验结果表明：焊缝金属在加氢反应器中运行５ａ后产生了明显的脆化，其脆化是由回火脆化产生的。 The test blocks in the hydrogenation reactor after 5 years operation were studied, and the temper brittleness of the weld metal in the test block was evaluated. At the same time, the weld metal after dehydrogenation and de-embrittlement treatment were tested. The experimental results show that the weld metal has obvious embrittlement after running 5a in the hydrogenation reactor. The embrittlement is caused by temper embrittlement produced.