Investigation effect of resistance spot welding parameters on dissimilar DP1000HF/CP800 steel joints

Recently, advanced high strength steels (AHSS) have gained importance especially in automobile industry due to excellent tensile and elongation properties. Dual phase and complex steels are among prominent members of the AHSS family. DP steels contains martensite within the ferrite matrix while the CP steels contains bainite, retained austenite, martensite and ferrite. The tensile strength of these steels can reach up to 1200 MPa. Also, new grades of the DP steels offer high formability with high tensile strength. In this work, resistance spot weldability of dissimilar CP800 and high formability grade of DP1000HF steel joint were investigated. Tensile-shear tests, weld nugget diameters and electrode indentation depths were evaluated with microstructural examinations. A weld lobe was determined in the light of obtained findings and standards. According to the results, SCHAZ of the DP1000HF is the weakest region of the joint affecting the tensile-shear strength. Maximum tensile-shear strength was 26380 N at 25 cycle welding time and 9.44 kA welding current where diameter of the weld nugget was measured as 9780 µm. Interfacial fracture separation mode was generally obtained below weld nugget diameter of 7500 µm. CP800 exhibited less electrode indentation depth compared to DP1000HF. The difference in electrode indentation depths between CP800 and DP1000HF was increased by raising the heat input. © 2022, Indian Academy of Sciences.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPESWe would like to thank the National Council for the Improvement of Higher Education, Brazil (CAPES) for providing a scholarship to the first author. This study was supported by the Federal University of Grande Dourados, Dourados, MS

The Frequency of HLA Class I and II Alleles in Turkish Childhood Acute Leukaemia Patients

In this study, blood samples were taken from 200 patients with childhood acute leukaemias, including acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML), and from 100 healthy volunteers (controls). The frequency of the human leucocyte antigen (HLA)-DRB1*04 allele was significantly higher, and the frequencies of the HLA-A23 and HLA-B7 antigens were significantly lower, in patients with ALL compared with controls. Among patients with AML, the frequency of the HLA-B49 antigen and the HLA-DRB1*15 allele were significantly higher, whereas the frequencies of the HLA-A11 and HLA-B38 antigens were significantly lower compared with controls. The frequency of the HLA-DRB1*04 allele was also significantly higher in male patients with ALL and AML, whereas the HLA-DRB1*13 allele was found significantly less frequently in male AML and female ALL patients than in controls. To date, this is the only study to evaluate the associations between HLA molecules and leukaemia in a Turkish population with acute childhood leukaemia