Ti-V-Nb微合金管线钢水下焊接粗晶区的韧性与沉淀物行为
BEHAVIOR OF CGHAZ TOUGHNESS AND PRECIPITATES OF UNDERWATER WELDED Ti-V-Nb MICROALLOYED PIPELINE STEELS
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摘要: 对X60，X65和X70三种微合金管线钢水下焊接及空气中焊接热影响粗晶区（CGHAZ）的显微组织、冲击韧性以及Ti-V-Nb沉淀物的尺寸分布和溶解行为进行了考察，并用X射线能谱仪测定了沉淀物的成分。结果表明，高Ti钢（X60，X70）粗晶区的晶粒尺寸比低Ti钢（X65）小，冲击韧性也高于X65钢，这与不同微合金沉淀物（富Ti和富V）在焊接热循环中的稳定性以及它们在母材中不同的尺寸分布有关。水下湿法焊接较快的冷却速度导致其粗晶区中含较多的马氏体，因而冲击韧性低于空气中焊接。
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关键词:
- 沉淀物 /
- 微合金化 /
- 水下焊接 /
- 粗晶区（CGHAZ） /
- 韧性
Abstract: Microstructure, impact toughness and precipitation behaviors of Ti-V-Nb particles in both the underwater and in-air welded coarse-grained heat-affected zone(CGHAZ) of X60, X65 and X70 microalloyed pipeline steels were investigated.The precipitate composition was also examined with Energy Disparsive X-ray(EDX) unit.The results showed that grain size of high-Ti steels (X60 and X70) CGHAZ zone was smaller than that of low Ti steels(X65) and impact toughness higher than that of it.It is related to the stability of different microalloying precipitates(Ti-rich and V-rich) in the thermal weld cycles and their different size distributions in parent materials.Higher cooling speed of underwater wet welding resulted in the presence of greater quantity martensite in the CGHAZ so that their impact toughness was lower than that of in-air welding.-
Key words:
- precipitate /
- microalloying /
- underwater welding /
- coarse-grained heat-affected zone (CGHAZ) /
- toughness
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