-70 ℃用压力容器钢焊接热影响区组织与韧性研究
Research on Microstructure and Toughness of Weld Heat Affected Zone of Pressure Vessel Steel Used at -70 ℃
周中喜1， 王 锐2， 张 晖1， 何宜柱1
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作者单位：1.安徽工业大学 材料科学与工程学院，安徽 马鞍山 243002；2. 湖州市特种设备检测中心，浙江 湖州 313000
中文关键字：-70 ℃；HAZ；针状铁素体；低温韧性
英文关键字：-70℃; HAZ; acicular ferrite; low-temperature toughness
中文摘要：实验研究了-70 ℃用压力容器钢焊接HAZ的显微特征及冲击韧性。结果表明：在HAZ部位，主要由针状铁素体+准多边形铁素体的复合组织组成，这种复合组织具有优异的低温韧性；两种组织之间的界面以及针状铁素体条束之间的界面均为大角度晶界，能够对裂纹的扩展起到有效的阻碍作用，增加裂纹扩展功，使得焊接HAZ具有良好的低温韧性，-70 ℃时冲击功平均值可以达到200 J以上，远高于国家标准27 J。
英文摘要：The microstructure characteristics and low temperature toughness of weld HAZ of pressure vessel steel used at -70 ℃ were studied. It is shown that the HAZ has excellent low-temperature toughness due to the mixed microstructure of acicular ferrite and quasi-polygonal ferrite in it. Both the grain boundaries between the two microstructure and the grain boundaries between acicular ferrites are the large angle boundary, which can inhibit cleavage crack from propagation and improve the propagation energy of the crack. The mixed microstructure shows the capability to attain such an excellent low-temperature toughness that the average Charpy-V impact energy can reach above 200 J at -70℃, which is 27 J far higher than that of the national standard.