اتصالات بین فولاد زنگ نزن سوپر دو فازی و فولاد HSLA

Effect of heat input on microstructure and mechanical properties of

dissimilar joints between super duplex stainless steel and high strength low alloy steel

اثر حرارت ورودی بر ریزساختار و خواص مکانیکی اتصالات غیر مشابه بین

فولاد زنگ نزن سوپر دو فازی و فولاد کم آلیاژ با استحکام بالا

ABSTRACT

In the present study, microstructure and mechanical properties of UNS S32750 super duplex stainless steel (SDSS)/API X-65 high strength low alloy steel (HSLA) dissimilar joint were investigated. For this purpose, gas tungsten arc welding (GTAW) was used in two different heat inputs: 0.506 and 0.86 kJ/mm. The microstructures investigation with optical microscope, scanning electron microscope and X-ray diffraction showed that an increase in heat input led to a decrease in ferrite percentage, and that detrimental phases were not present. It also indicated that in heat affected zone of HSLA base metal in low heat input, bainite and ferrite phases were created; but in high heat input, perlite and ferrite phases were created. The results of impact tests revealed that the specimen with low heat input exhibited brittle fracture and that with high heat input had a higher strength than the base metals.

 

مشخصه یابی ریزساختارها و انحراف جهت گیری رشد دندریت فاز Al2Cu

Characterization of microstructures and growth orientation deviating

of Al2Cu phase dendrite at different directional solidification rates

مشخصه یابی ریزساختارها و انحراف جهت گیری رشد دندریت فاز Al2Cu

در نرخ های انجماد جهت دار مختلف 

ABSTRACT

At different directional solidification rates (10, 20 and 100 mm/s), microstructures and growth orientation variations of Al2Cu dendrite in Al-40%Cu alloy were characterized. When solidification rates were ranged from 10 to 100 mm/s, three-dimensional microstructure of Al2Cu dendrite changed from faceted L-shaped patterns to non-faceted complex dendrite morphology in transverse section. By the macro and micro orientation analysis characterize methods, [001] growth direction of Al2Cu dendrites with different morphologies was determined. The deviation angle between [001] direction and the heat flow direction was increased with solidified rate increasing. The experimental results showed that the regular solidified microstructure and growth orientation along the heat flow direction could be well controlled under lower directional solidification rate.