EFFECTS OF Cr PLATING LAYER ON SHEAR STRENGTH AND INTERFACE BONDING CHARACTERISTICS OF MILD STEEL/CFRP JOINT BY LASER HEATING

Abstract

The carbon fiber reinforced polymer (CFRP) has been widely used in aerospace and military fields, whereas it is still at its initial stage in the field of automobile manufacturing, wind power generation and so on. One of the main reasons to restrict its wide application is that the strength of metal/CFRP joint is very low and cannot meet the industrial requirements. In this study, an investigation of the laser joining between CFRP and mild steel with Cr electroplating was presented. The influence of Cr plating layer on shear strength of mild steel/CFRP lap joint was studied and the bonding characteristics of the joint interface were analyzed by SEM and XPS. The results show that Cr plating layer can greatly improve the shear force and shear strength of mild steel/CFRP joint. The shear force increases from 2237.37 N to 6127.81 N and the shear strength increases from 9.32 MPa to 22.14 MPa. For the mild steel/CFRP joint without Cr plating, the shear failure happens at the interface. However, for the mild steel/CFRP joint with Cr plating, the shear failure happens at the porosities zone in the CFRP. It means that the Cr plating can improve the interfacial bonding strength. The results of SEM observation and XPS analyses show that the mechanical bonding represented as the "anchoring effect" is achieved at the mild steel/CFRP interface both with and without Cr plating. But the chemical bonding is detected only at the mild steel/CFRP interface with Cr plating, which is considered as an important reason that the Cr plating can improve the bonding strength of the mild * Ù ±  ¼Ü 51275271

Characteristics and formation mechanism of porosities in CFRP during laser joining of CFRP and steel

“…However, the formation mechanism of porosities in CFRP during laser joining of the CFRP and metal is still unclear. Shan et al [25,29] found that when the temperature is higher than 350°C, the resin matrix of CFRP pyrolysis occurs, producing gaseous products such as CO 2 and NH 3 . The hydrocarbon series gases are detected by a Q-mass spectrometer during the laser joining of SUS304 stainless steel and PET [33].…”

“…One significant issue related to the laser joining of polymers and CFRP to metal is the porosity formation in the joining area caused by laser heating [25,[29][30][31][32][33][34][35]. When laser joining magnesium alloy and amorphous polyethylene terephthalate (PET), many small porosities are formed in the interior of the PET resin matrix near the interface [30].…”

“…Moreover, adhesive bonding requires surface treatment before joining, which is very expensive [14][15][16][17][18][19]. Recently, many innovative joining technologies have been investigated, such as friction spot welding [20], resistance welding with inserted conductive elements [21,22], ultrasonically welding [23], and laser joining [24,25]. Compared with the other welding technologies, laser joining has many advantageous such as non-contact processing, high efficiency and accessibility, high flexibility, and avoiding adding expensive elements such as TiO 2 and carbon fibers [26][27][28].…”

Performance and mechanism of laser transmission joining between glass fiber‐reinforced PA66 and PC

“…It is inferred that the new generated Al-O-C is contained in the Tan et al 27 studied effects of Cr plating layer on shear strength and interface bonding characteristics of mild steel/glass fiber reinforced polymers (GFRP) joint by laser heating. They also found that the metal Cr facilitated the opening of C5O groups in polymers resulting in the generation of Cr-O-C compounds.…”

Influence of Processing Parameters on Laser Direct Joining of CFRTP and Stainless Steel

“…Katayama and Kawahito [22] exhibited that the laser irradiated on stainless steel could generate a Cr 2 O 3 transition layer on the interface of plastic/stainless steel. Moreover, the research of Tan et al [23] revealed that the existence of the Cr layer on the steel surface enhanced the shear strength of the CFRP/steel joint by the Cr-O-PA6T bonding along the joint interface. e Roesner et al [24] demonstrated that the machined microgrooves on the metal surface increased the strength of the laser joined plastic/aluminum joint to 24 MPa.…”