H. Najafi

[ 1 ] - Mechanical Properties of Dissimilar Welds between AISI 4130 and GOST09ch16N4B

Mechanical properties of dissimilar weld joints between GOST09ch16N4B (a martensitic stainless steel) and AISI 4130 thin sheets made by gas tungsten arc welding (GTAW) were studied using ER410NiMo and ER100S-G filler metals in post weld heat treated conditions. Heat treatment cycles consisted of austenitization at 900, 950 and 1000 °C for 1 h and this was followed by oil cooling and tempering a...

[ 2 ] - Hot tensile properties of 9Cr-2WVTa reduced-activation ferritic/martensitic steel

Reduced-activation ferritic/martensitic steels have been developed by replacing molybdenum by tungsten and niobium by tantalum in commercial elevated-temperature Cr–Mo steels to reduce half-life of radioactive isotopes. The objective of this study was to investigate tensile properties of a reduced-activation ferritic/martensitic steel (9Cr-2WVTa) in normalized-tempered (NT) and quenched-tempere...

[ 3 ] - بررسی تغییر خواص استحکامی و سختی فولادH13طی خزش کوتاه مدت

تغییر در خواص استحکامی و سختی آلیاژها عامل اصلی در تغییر نرخ کرنش طی خزش است. بنابراین، اندازه گیری این خواص و مطالعه ارتباط آنها با مقاومت خزشی دارای اهمیت می‌باشد. در این پژوهش، ارتباط بین داده‌های سختی و مقاومت به خزش فولاد H13 طی خزش کوتاه مدت مورد مطالعه قرار گرفته است. آزمون‌های خزش تا شکست و نیز کرنش 1% در بازه دمایی C 600 ـ500 و تنش MPa 5/926 ـ872 انجام شد. سختی‌سنجی بر روی کلیه نمونه‌...

[ 4 ] - تاثیر افزودن نایوبیم و دمای آستنیته بر ریزساختار و خواص مکانیکی حاصل از فرآیند مارتنزیتی یک فولاد کم‌کربن

در این پژوهش تاثیر افزودن نایوبیم و دمای آستنیته بر خواص مکانیکی و ریزساختار فولادی کم‌کربن پس از اعمال فرآیند مارتنزیتی مورد بررسی قرار گرفته است. نمونه‌ها پس از ریخته‌گری و نورد داغ؛ در دماهای 900، 1000، 1100 و C 1200 به‌مدت یک ساعت آستنیته و سپس در آب کوئنچ شدند که حاصل آن ریزساختار مارتنزیتی (همراه مقدار کمی فریت ویدمن‌اشتاتن) بود. بیشینه سختی در نمونه حاوی نایوبیم آستنیته‌شده در دمای C 1...

[ 5 ] - Welding of 304L Stainless Steel to 409 Stainless Steel with GMAW Process Using ER316LSi and ER309LMo Filler Metals

Dissimilar welding of AISI 304L austenitic stainless steel to AISI 409 ferritic stainless steel with GMAW process usingtwo Ar-O2 and Ar-CO2 shielding gas mixtures was studied. ER316LSi and ER309LMo filler metals were chosen by considering 5 and 15% delta ferrite according to the Schaeffler equations and diagram. Based on the observations, both filler metals accompanied by Ar-2%O2 shielding gas ...

[ 6 ] - Welding of 304L Stainless Steel to 409 Stainless Steel with GMAW Process Using ER316LSi and ER309LMo Filler Metals

Dissimilar welding of AISI 304L austenitic stainless steel to AISI 409 ferritic stainless steel with GMAW process usingtwo Ar-O2 and Ar-CO2 shielding gas mixtures was studied. ER316LSi and ER309LMo filler metals were chosen by considering 5 and 15% delta ferrite according to the Schaeffler equations and diagram. Based on the observations, both filler metals accompanied by Ar-2%O2 shielding gas ...

[ 7 ] - Effect of Oxide flux powders of SiO2, MoO3 and CuO on the diffusion depth, microstructure and microhardness of GTAWed precipitation hardening martensitic 17-4PH steel

In this investigation the effect of oxides powders of SiO2, MoO3 and CuO on the depth of penetration, microstructure and hardness profile of GTAWeld precipitation hardening martensitic 17-4PH was assessed. Samples were taken from 17-4PH steel sheet with the dimensions of 150*50 mm and with the thickness of 5 mm, and were welded by oxide powder of SiO2, MoO3 and CuO. Results showed that using ox...

[ 8 ] - Effect of Oxide flux powders of SiO2, MoO3 and CuO on the diffusion depth, microstructure and microhardness of GTAWed precipitation hardening martensitic 17-4PH steel

In this investigation the effect of oxides powders of SiO2, MoO3 and CuO on the depth of penetration, microstructure and hardness profile of GTAWeld precipitation hardening martensitic 17-4PH was assessed. Samples were taken from 17-4PH steel sheet with the dimensions of 150*50 mm and with the thickness of 5 mm, and were welded by oxide powder of SiO2, MoO3 and CuO. Results showed that using ox...