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金属学报  2019, Vol. 55 Issue (5): 575-584    DOI: 10.11900/0412.1961.2018.00375
  本期目录 | 过刊浏览 |
保护气成分对1000 MPa级高强熔敷金属组织特征的影响
1. 钢铁研究总院焊接所 北京 100081
2. 清华大学机械工程系 北京 100084
Influence of Shielding Gas Composition on Microstructure Characteristics of 1000 MPa Grade Deposited Metals
Tongbang AN1,2(),Jinshan WEI1,Jiguo SHAN2,Zhiling TIAN1
1. Welding Institute, Central Iron & Steel Research Institute, Beijing 100081, China
2. Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
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通过附带EDS的FEGSEM、EBSD、TEM等实验方法,研究了保护气成分(Ar+5%CO2、Ar+10%CO2、Ar+20%CO2、Ar+30%CO2,体积分数)对1000 MPa级高强熔敷金属组织特征的影响,阐明了保护气成分对组织转变的影响机制。结果表明,随着保护气中CO2含量增加,1000 MPa级熔敷金属强度略有下降,而冲击韧性先升高后降低。不同保护气熔敷金属均由马氏体/贝氏体混合组织及板条间残余奥氏体组成。随着保护气中CO2含量增加,熔敷金属中贝氏体相变体积分数为50%时的温度(B50)与马氏体相变开始温度(Ms)相变温度区间增大,适宜贝氏体形核的夹杂物数量增多,随贝氏体含量(体积分数)由8%增加到29.6%,其形核位置从原始奥氏体晶界向原始奥氏体晶界及晶内夹杂物处共同形核转变,熔敷金属组织形貌由“平行状”向“交织状”转变,分割细化组织,有利于高强熔敷金属强韧性的改善。

关键词 保护气成分1000 MPa级熔敷金属氧化物夹杂显微组织特征    

In recent years, high and ultra-high strength steels have been developed and used in light-weight constructions such as the structural members of mobile equipment in order to reduce weight and fabrication costs and to enhance the performance. Welding of steels with yield strength of more than 900 MPa is particularly challenging because of the toughness requirements for the weld metal, which calls for welding consumables of high strength and good toughness. Weld metals have been produced for a variety of welding methods with yield strength up to or above 1000 MPa, but their impact toughness remained only at medium yield strengths. Proper microstructure is the key to meeting this requirement, and its final microstructure depends on the chemical composition and cooling rate. For the deposited metal produced by gas metal arc welding (GMAW), the composition is dependent on the welding wire and shielding gas. The cooling rate of the weld metal is controlled by a combination of heat input and heat extraction. It is known that the addition of CO2 to argon based shielding gas is effective for improvement of productivity in GMAW welding of steel. Through the chemical reaction in the welding arc, CO2 in the shielding gas can affect the chemical composition of the weld metal, and its microstructure. The 1000 MPa grade deposited metals was welded with GMAW, and the effects of shielding gas composition (Ar+(5%~30%)CO2, volume fraction) on the general compositional and microstructural characteristics of deposited metals, including nonmetallic inclusions, were experimentally characterized with SEM, EBSD and TEM. The microstructure of the deposited metals is mainly composed of martensite and bainite. With the increase of CO2 content (5%~30%), the strength of the deposited metals decrease slightly and the impact toughness increases first and then decreases. Meanwhile, the transformation range (B50-Ms) of the deposited metal increases, the bainite content increases (8%~29.6%) with the quantity of inclusions that are suitable for bainite nucleation increases, and the nucleation position changes from the original austenite grain boundary to the common nucleation on the original austenite grain boundary and inclusions within the grain. At the same time, the microstructure morphology of the deposited metal changes from parallel to intertexture, which presented an intersected configuration and microstructure refinement.

Key wordsshielding gas composition    1000 MPa grade deposited metal    oxide inclusion    microstructure characteristics
收稿日期: 2018-08-16     
ZTFLH:  TG442.3  
通讯作者: 安同邦     E-mail:
Corresponding author: Tongbang AN     E-mail:
作者简介: 安同邦,男,1982年生,博士


安同邦,魏金山,单际国,田志凌. 保护气成分对1000 MPa级高强熔敷金属组织特征的影响[J]. 金属学报, 2019, 55(5): 575-584.
Tongbang AN, Jinshan WEI, Jiguo SHAN, Zhiling TIAN. Influence of Shielding Gas Composition on Microstructure Characteristics of 1000 MPa Grade Deposited Metals. Acta Metall Sin, 2019, 55(5): 575-584.

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Shielding gasCSiMnNi+Cr+MoTiONFe
表1  不同保护气熔敷金属的化学成分

Shielding gas





Charpy absorbed energy / J

Vickers hardness



RT-40 ℃
表2  不同保护气熔敷金属的力学性能
图1  不同保护气末层焊道熔敷金属显微组织的SEM像
图2  不同保护气熔敷金属显微组织的TEM明场像,残余奥氏体明场像、暗场像及其SAED花样
图3  不同保护气熔敷金属板条块亚结构EBSD像和反极图
图4  不同保护气成分熔敷金属中夹杂物BSE-SEM像

Shielding gas

Average diameter


Maximum size


Number density

104 mm-2

Area fraction


表3  不同保护气熔敷金属中夹杂物统计
Shielding gasPositionOAlSiSTiMn








表4  夹杂物化学成分EDS分析
图5  不同保护气下末层焊道熔敷金属显微组织彩色OM像
图6  熔敷金属中贝氏体相变体积分数为50%时的温度(B50)与马氏体相变开始温度(Ms)随保护气中CO2含量的变化关系
图7  不同保护气熔敷金属凝固组织转变机制示意图
图8  夹杂物处形核长大的贝氏体板条TEM像和SEM像
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