Fatih Hayat
钢铁研究学报(英文版)
Zinc coated dual phase 600 steel (DP 600 grade) was investigated, utilisation of which has gradually increased with each passing day in the automotive industry. The adhesive bonding (AB), resistance spot welding (RSW), and adhesive weld bonding (AWB) joints of the zinc coated DP 600 steel were investigated. Additionally, the zinc coating was removed using HCL acid in order to investigate the effect of the coating. The microstructure, tensile shear strengths, and fracture properties of adhesive bonding (AB), resistance spot welding (RSW), and adhesive weld bonding (AWB) joints of the coated and uncoated DP 600 steel were compared. In addition, a mechanical-electrical-thermal coupled model in a finite element analysis environment was utilised. The thermal profile phenomenon was calculated by simulating this process. The results of the tensile shear test indicated that the tensile load bearing capacity (TLBC) values of the coated specimens among the three welding methods were higher than those of the uncoated specimens. Additionally, the tensile strength of the AWB joints of the coated and uncoated specimens was higher than that of the AB and RSW joints. It was determined that the fracture behaviours and the deformation caused were different for the three welding methods.
关键词:
advanced high strength steel
,
DP600
,
adhesive weld bonding
,
microstructure
,
deformation
,
fracture
Fatih Hayat
材料科学技术（英文）
In this study, resistance spot weldability of 180 grade bake hardening steel (BH180), 7123 grade interstitial free steel (IF7123) and 304 grade austenitic stainless steel (AISI304L) with each other was investigated. In the joining process, electrode pressure and weld current were kept constant and six different weld time were chosen. Microstructure, microhardness, tensile-shear properties and fracture types of resistance spot welded joints were examined. In order to characterize the metallurgical structure of the welded joint, the microstructural profile was developed, and the relationship between mechanical properties and microstructure was determined. The change of weld time, nugget diameter, the HAZ (heat affected zone) width and the electrode immersion depth were also investigated. Welded joints were examined by SEM (scanning electron microscopy) images of fracture surface. As a result of the experiment, it was determined that with increasing weld time, tensile shear load bearing capacity (TLBC) increased with weld time up to 25 cycle and two types of tearing occurred. It was also determined that while the failure occurred from IF side at the BH180+IF7123 joint, it occurred from the BH180 side at the BH180+AISI304L joint.
关键词:
Resistance spot welding
Fatih Hayat
,
Hüseyin Uzun
钢铁研究学报(英文版)
Grade A (GA) and high strength steel DH36 ship steels possessing different chemical compositions were used, and strength properties of GA steel and DH36 steel were compared. Additionally, 4 types of dual phase (DP) steels with different martensite volume fractions (MVFs) were produced from GA steel by means of heat treatment and they were compared with other steels through conducting microstructure, microhardness, tensile and impact tests. The fracture surfaces of specimens (DH36, GA and DP steels) exposed to tensile and Charpy impact tests were investigated by scanning electron microscope. Furthermore, it was found that the specimens quenched from 800 and 900 ℃ had better strength than DH36 steel. The tensile test results indicated that the tensile strength of DP steel water quenched from 900 ℃ was 3 times that of GA steel and twice that of DH36 steel.
关键词:
Grade A ship steel
,
DH36 ship steel
,
dual phase steel
,
martensite
,
mechanical property
,
fracture
