Study on the Microstructure and Mechanical Properties of Copper/Steel Joints Welded by Non-uniform Laser Source

doi:10.3901/JME.2025.06.151

Abstract

Abstract: Copper-steel composite structures are widely used due to their advantages in both cost and performance. However, there are differences in material physical properties and difficulties in welding. Traditional welding methods using a uniform heat source often lead to significant elemental segregation in the joints and severe softening in the copper side heat-affected zone. A full-domain power modulation laser oscillating welding system is employed to design a non-uniform heat source to meet the different heat requirements of the two materials. Three different power modes were investigated to study their effects on the elements diffusion, microstructure, and properties of Cu/304SS dissimilar joints. The findings revealed that when the power ratio between the copper and steel sides was set at 6:4, the joint exhibited the maximum degree of liquid phase separation, with the solid solution of copper and steel uniformly dispersed in the weld. The joint exhibited the lowest degree of elemental segregation and the least softening. Additionally, it demonstrated a maximum tensile strength of 211 MPa, which was 93 % of the copper base material (226 MPa). It provides a novel approach for the flexible control of energy distribution during the welding process of dissimilar joints between copper and steel.

Key words: oscillation, microstructure, dissimilar metal, mechanical properties, mechanism

CLC Number:

TG156

HAN Jing, SHI Yu, LI Guang, ZHANG Hang, LU Gang. Study on the Microstructure and Mechanical Properties of Copper/Steel Joints Welded by Non-uniform Laser Source[J]. Journal of Mechanical Engineering, 2025, 61(6): 151-159.

References

[1] SADEGHIAN A，IQBAL N. A review on dissimilar laser welding of steel-copper, steel-aluminum,aluminum-copper, and steel-nickel for electric vehicle battery manufacturing[J]. Optics & Laser Technology，2022，146：107595.
[2] LI Jianmin，CAI Yuanzheng，YAN Fei，et al. Porosity and liquation cracking of dissimilar Nd:YAG laser welding of SUS304 stainless steel to T2 copper[J]. Optics & Laser Technology，2020，122：105881.
[3] NGUYEN Q，AZADKHOU A，AKBARI M，et al. Experimental investigation of temperature field and fusion zone microstructure in dissimilar pulsed laser welding of austenitic stainless steel and copper[J]. Journal of Manufacturing Processes，2020，56：206-215.
[4] JOSHI G R，BADHEKA V J. Processing of bimetallic steel-copper joint by laser beam welding[J]. Materials and Manufacturing Processes，2019，34(11)：1232-1242.
[5] CHEN Shuhai，HUANG Jihua，XIA Jun，et al. Influence of processing parameters on the characteristics of stainless steel/copper laser welding[J]. Journal of Materials Processing Technology，2015，222：43-51.
[6] THOMAS N，MATHEW A，GEORGE K，et al. Microstructural and mechanical properties evaluation of tungsten inert gas-welded 316 stainless steel and pure copper joint[J]. Metallography, Microstructure, and Analysis，2020，9(5)：678-684.
[7] GAO Ming，ZHANG Yazhou，MENG Yunfei. Interface homogenization and its relationship with tensile properties of laser-arc hybrid welded Al/steel butt-joint via beam oscillation[J]. Journal of Materials Science，2021，56(25)：14126-14138.
[8] CHEN Cong，XIANG Yunzhong，GAO Ming. Weld formation mechanism of fiber laser oscillating welding of dissimilar aluminum alloys[J]. Journal of Manufacturing Processes，2020，60：180-187.
[9] KAR J，ROY S K，ROY G G. Effect of beam oscillation on electron beam welding of copper with AISI-304 stainless steel[J]. Journal of Materials Processing Technology，2016，233：174-185.
[10] JIANG Zhenguo，CHEN Xi，YU Kun，et al. Improving fusion zone microstructure inhomogeneity in dissimilar-metal welding by laser welding with oscillation[J]. Materials Letters，2020，261：126995.
[11] WANG L L，WEI H L，XUE J X，et al. A pathway to microstructural refinement through double pulsed gas metal arc welding[J]. Scripta Materialia，2017，134：61-65.
[12] 史杰. 铜-钢异种材料焊接工艺及组织演变行为研究[D]. 西安：西安理工大学，2019. SHI Jie. Fusion welding on copper-steel dissimilar materials and joint microstructure evolution[D]. Xi’an：Xi’an University of Technology，2019.
[13] SAHUL M，TOMČÍKOVÁ E，SAHUL M，et al. Effect of disk laser beam offset on the microstructure and mechanical properties of copper-AISI 304 stainless steel dissimilar metals joints[J]. Metals，2020，10(10)：1294.
[14] 陈永城，罗子艺，张宇鹏，等. 紫铜-304不锈钢激光焊接接头显微组织及力学性能[J]. 材料导报，2019，33(1)：325-329. CHEN Yongcheng，LUO Ziyi，ZHANG Yupeng，et al. Microstructure and mechanical properties of copper/304 stainless steel joints welded by laser beam[J]. Materials Reports，2019，33(1)：325-329.
[15] CHEN Shuhai，HUANG Jihua，XIA Jun，et al. Microstructural characteristics of a stainless steel/copper dissimilar joint made by laser welding[J]. Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science，2013，44(8)：3690-3696.
[16] NING Jie，ZHANG Linjie，YIN Xianqing，et al. Mechanism study on the effects of power modulation on energy coupling efficiency in infrared laser welding of highly-reflective materials[J]. Materials & Design，2019，178：107871.
[17] SCHWEIER M，HEINS J F，HAUBOLD M W，et al. Spatter formation in laser welding with beam oscillation[J]. Physics Procedia，2013，41：20-30.
[18] CHEN Cong，ZHOU Haipeng，WANG Changjian，et al. Laser welding of ultra-high strength steel with different oscillating modes[J]. Journal of Manufacturing Processes，2021，68：761-769.
[19] HAO Kangda，LI Geng，GAO Ming，et al. Weld formation mechanism of fiber laser oscillating welding of austenitic stainless steel[J]. Journal of Materials Processing Technology，2015，225：77-83.
[20] HAN Jing，SHI Yu，ZHANG Gang，et al. Minimizing defects and controlling the morphology of laser welded aluminum alloys using power modulation-based laser beam oscillation[J]. Journal of Manufacturing Processes，2022，83：49-59.
[21] ROY C，PAVANAN V V，VISHNU G，et al. Characterization of metallurgical and mechanical properties of commercially pure copper and AISI 304 dissimilar weldments[J]. Procedia Materials Science，2014，5：2503-2512.
[22] 蔡远征. T2紫铜/304不锈钢异种合金激光自熔焊工艺研究[D]. 武汉：华中科技大学，2018. CAI Yuanzheng. Investigation on dissimilar alloy laser welding of T2 copper/SUS 304[D]. Wuhan：Huazhong University of Science & Technology，2018.
[23] 李静. T2-304焊接接头组织与性能分析及其匹配焊材的研究[D]. 西安：西安理工大学，2020. LI Jing. Microstructure and performance analysis and research on matching welding materials of T2-304 joint[D]. Xi’an：Xi’an University of Technology，2020.