中文摘要：

比较2.25Cr-1Mo钢埋弧焊焊缝经过720℃保温2 h（工艺1）以及680℃保温12 h（工艺2）的冲击性能,结果表明热处理工艺1具有更好的冲击韧度;进一步测试工艺1接头液氮处理后的冲击性能,发现冲击韧度降低,推测残余奥氏体质量分数是造成这不同热处理工艺冲击性能差异的因素。采用振动样品磁强计和电子背散射衍射技术分别研究两种热处理试样的磁极化强度和相分布,获得了两种热处理工艺处理后焊缝金属的残余奥氏体质量分数,磁法测量表明焊后经工艺1处理后存在约3%左右的残余奥氏体,而经工艺2处理后残余奥氏体为0.2%;EBSD分析结果：工艺1的残余奥氏体质量分数为3.49%,工艺2的质量分数为0.18%,证实了焊缝中残余奥氏体质量分数的变化对冲击性能具有一定的影响。

英文摘要：

Impact toughness tests are used to compare two different kinds of temper heat treatment for the filler metal of 2.25Cr-1Mo steel.In the first temper process,the top temperature is 720 ℃ and the holding time is 2 h.The other temper treatment includes 680 ℃ and 12 h.The first heat treatment process shows a better impact toughness.To study what causes the difference,the joints processed with the first temper treatment are dipped into liquid nitrogen to decompose residual austenite in welds.The later tests show that impact toughness is deceased super cooling,which suggests austenite may be an important factor for welds toughness.To validate the assumption,magneto-polarization intensity and electron backscattered diffraction of different samples are investigated to quantify residual austenite quality and distribution through vibration sample magnetometer（VSM） and electron back-scattering diffraction（EBSD） separately.After the first temper process,the welding metal has about 3% residual austenite quality investigated by VSM,and has 0.2% after the second temper process;On the other hand,it has about 3.49% residual austenite quality investigated by EBSD after the first process,and has about 0.18% after the second process.The measurement results show the difference of residual austenite content with different heat treatment process,which makes sure the effect of residual austenite content on the impact toughness of the filler metal.