中文摘要：

测定了稀土脱氧和铝稀土复合脱氧钢焊接热影响区（HAZ）的连续冷却转变曲线,分析了2种钢中的夹杂物种类及其HAZ的显微组织和常温冲击韧性。得到如下结论：稀土脱氧使钢中主要夹杂物从Mn S转变为RE2O2S＋Mn S,而铝稀土复合脱氧钢中夹杂物主要是Ce Al O3＋Ce2S3＋Mn S。稀土脱氧钢HAZ中能获得晶内铁素体的冷速较宽,约为0.5~7.5℃/s。铝稀土复合脱氧钢HAZ获得晶内铁素体组织较稀土脱氧钢要困难一些,适合晶内铁素体形成的冷速变窄为1~3℃/s,HAZ中晶内铁素体的含量明显低于稀土处理钢,Al脱氧弱化了稀土处理对钢HAZ组织的改善作用。焊接热输入线能量为100 k J/cm时,稀土脱氧能够明显改善钢HAZ的室温冲击韧性。

英文摘要：

In this paper, the continuous cooling transformation curves of the welding heat affected zones （HAZ） were measured in steels deoxidized by rare earth （RE） and composite aluminum ＋ RE, respectively. The composition of inclusions and impact toughness of HAZ at room temperature were analyzed in the above-mentioned two steels. The obtained results were as follows： the main inclusions in the steel changed from binS to RE202S ＋ MnS after rare earth treatment,the composite aluminum ＋ RE deoxidation changed the inclusions into CeAI03 ＋ Ce2S3 ＋ MnS in C-Mn steel. The profitable cooling rate range for intragranular ferrite formation was wide during continuous cooling, about 0.5 - 7.5 ~C/s, in the HAZ of rare earth treated C-Mn steel. While in the aluminum ＋ RE deoxidized steel, the profitable cooling rate ranged for HAZ to obtain intragranular ferrite was narrow,only about 1 -3 ~C/s, meaning it was difficult for intragranular ferrite formation. The content of intragranular ferrite in the HAZ of RE killed steel was more than that in the HAZ of aluminum ＋ RE deoxidized steel, demonstrating that A1 deoxidation weaken the effect of RE deoxidization on the microstructure improvement of HAZ in steel. When welding heat input line energy was 100 kJ/cm, rare earth treatment in the steel could improve HAZ impact toughness at room temperature obviously.