Microstructure and Mechanical Properties of 20Cr32Ni1Nb Superalloy Weld Joint

ZHANG Zehao; XIAO Mingying

doi:10.7512/j.issn.1001-2303.2024.04.21

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Microstructure and Mechanical Properties of 20Cr32Ni1Nb Superalloy Weld Joint
Vol. 54, Issue 4, Pages: 141-147(2024)
Received：13 September 2023，

Revised：2023-10-11，

Published：25 April 2024
DOI： 10.7512/j.issn.1001-2303.2024.04.21
稿件说明：

移动端阅览

张泽浩，肖明颖.20Cr32Ni1Nb高温合金焊接接头组织及力学性能研究［J］.电焊机，2024，54（4）：141-147. DOI： 10.7512/j.issn.1001-2303.2024.04.21.

ZHANG Zehao, XIAO Mingying.Microstructure and Mechanical Properties of 20Cr32Ni1Nb Superalloy Weld Joint[J].Electric Welding Machine, 2024, 54(4): 141-147. DOI： 10.7512/j.issn.1001-2303.2024.04.21.

摘要

采用高镍和低镍两种焊丝氩弧焊接20Cr32Ni1Nb铸造耐热合金炉管，旨在研究20Cr32Ni1Nb高温合金焊接接头的组织和力学性能。通过金相、硬度和拉伸等表征测试方法对比分析两种焊接接头的显微组织和力学性能。结果表明，焊接接头的母材由柱状奥氏体晶粒和网状晶界构成，焊缝是由细小的针状或者柱状奥氏体晶粒和沿晶界分布的链状或者块状碳化物构成。受焊接热输入影响，热影响区的母材晶粒粗化，并在晶界处析出二次碳化物；焊接接头热影响区的显微硬度较母材下降约20 HV

0.2

；低镍焊缝的显微硬度略低于高镍焊缝，更接近于母材，约为220 HV

0.2

，这有利于改善焊接接头的整体力学性能。两种焊接接头拉伸性能均满足焊接评定要求，其短时拉伸力学性能相近，但低镍焊接接头的高温拉伸持久时间远超高镍焊接接头，达3.9倍，这是因为低镍焊缝更易析出碳化物，阻碍晶界滑移和位错聚集，进而提高其抗蠕变性能。低镍焊丝更适合20Cr32Ni1Nb合金的焊接。

Abstract

The 20Cr32Ni1Nb cast heat-resistant alloy furnace tube was welded by argon arc welding with high nickel and low nickel welding wires. The microstructure and mechanical properties of the two weld joints were compared and analyzed by optical microscopy

hardness test

and tensile test. The experimental results show that the base material of the weld joint is composed of columnar austenite grains and network grain boundaries

while the weld metal is composed of small needle or columnar austenite grains and chain or block carbides distributed along the grain boundaries. Affected by welding heat input

the grain size of the base metal located in the heat affected zone becomes larger and secondary carbides precipitate at the grain boundaries. The microhardness of the heat-affected zone of the weld joint decreases by about 20HV

0.2

compared to the base metal. The microhardness of low nickel welds is slightly lower than that of high nickel welds

which is similar to the base metal and is about 220HV

0.2

which is beneficial for improving the mechanical properties of weld joints. The tensile mechanical properties of the two weld joints meet the welding qualification requirements

d their short-term tensile mechanical properties are the same. However

the high-temperature tensile endurance of low-nickel weld joints is 3.9 times that of high-nickel weld joints. This is because low nickel alloy welds are more prone to precipitation of carbides

hindering grain boundary slip and dislocation aggregation

and improving their creep resistance.

关键词

Keywords

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