Dual-wire SAW experiment on economic Nb-bearing X70 steel

HUANG Zhijun; DENG Zhaojun; CUI Lei; ZHEN Shaopeng

doi:10.7512/j.issn.1001-2303.2020.09.30

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Dual-wire SAW experiment on economic Nb-bearing X70 steel
Vol. 50, Issue 9, Pages: 262-267(2020)
Published：2020
DOI： 10.7512/j.issn.1001-2303.2020.09.30
稿件说明：

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DOI：

HUANG Zhijun, DENG Zhaojun, CUI Lei, et al. Dual-wire SAW experiment on economic Nb-bearing X70 steel[J]. Eletric Welding Machine2020, 50(9): 262-267. DOI： 10.7512/j.issn.1001-2303.2020.09.30.

摘要

采用550 MPa级及650 MPa级无Nb焊丝对含Nb经济型X70钢进行了异丝双丝埋弧焊。结果表明

焊接接头力学性能满足要求

焊接热影响区冲击韧性富裕量高且波动较小;异丝熔融混合较为充分

焊缝性能较为均匀。过热区组织为粒状贝氏体

铁素体基体呈块状及板条状。尽管X70钢中Nb向焊缝过渡

但无论是焊态焊缝还是受热焊缝

透射电镜观察的析出物尺寸为200 nm～1.5μm

个别细小达80 nm

主要是Ti、Al、Mn或Si的氧化物

并不含Nb

这与X70钢母材中的析出物有明显不同。

Abstract

No-Nb wires of 550 MPa and 650 MPa grades were employed to carry out dual submerged arc welding test on economic Nb-bearing X70 steel. The mechanical properties of the welded joint met the technical requirements

and the HAZ had toughness with large margin and little fluctuation; the properties are uniform indicating a good mixture of the two wires in melting pool. The microstructure of GCHAZ is granular bainite with granular ferrite and plate ferrite. In spite of the Nb dilution from X70 parent metal to weld metal

the precipitates in welds of either as welded or reheated are still mainly oxides of Ti

Mn and Si

but without Nb

sizing from 200 nm to 1.5 μm

and singly 80 nm by TEM observation

which is much different with that in X70 steel.