مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

ریزساختار و خواص مکانیکی فولاد دوفازی تولید شده توسط نورد نامتقارن و آنیل میان بحرانی کوتاه‌مدت

نوع مقاله : پژوهشی اصیل

نویسندگان
دانشگاه صنعتی نوشیروانی بابل
چکیده
در پژوهش حاضر با استفاده از روشی نوین، فولاد دوفازی با استحکام بالا و انعطاف پذیری مطلوب از فولاد ساده کربنی با 16/0% کربن، تولید شد. با استفاده از آستنیته کردن، کوئنچ، نورد سرد نامتقارن و آنیل میان بحرانی در دماهای C˚770 و C˚800 و زمان های کوتاه نگهداری 1 و 5 دقیقه، فولاد دوفازی با ساختار فریت-مارتنزیت به دست آمد. به دلیل اعمال کرنش برشی یکنواخت از طریق نورد سرد نامتقارن، توزیع یکنواختی از فاز مارتنزیت در صفحات RD-TD و RD-ND مشاهده شد. با افزایش زمان نگهداری، کسرحجمی مارتنزیت در دمای C˚770 از 8 به 12 درصد و در دمای C˚800 از 10 به 33 درصد به ترتیب در زمان‌های 1 و 5 دقیقه رسید. با افزایش دما و زمان آنیل میان بحرانی مقدار مارتنزیت افزایش و سختی و استحکام بهبود یافت. نمونه تولید شده در دمای C˚800 و زمان 5 دقیقه، خواص مکانیکی عالی از جمله سختی HV 244 و استحکام MPa 1020 و انعطاف‌پذیری 5/12% را از خود نشان داد. همچنین به دلیل بالا بودن کسرحجمی مارتنزیت و در پی آن کاهش کربن محتوی آن، سختی این فاز کاهش یافته و در نتیجه تغییرشکل پلاستیک قابل توجه و کرنش‌سختی بالایی را از خود نشان داد. سطح شکست اکثر فولادهای دوفازی تولید شده عمدتا شامل دیمپل بود که نشان دهنده‌ی رفتار شکست نرم است.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Microstructure and mechanical properties of dual-phase steel produced by asymmetric rolling and short-term intercritical annealing

نویسندگان English

Fatemeh Yaghoobi
Roohollah Jamaati
Hamed Jamshidi Aval
Babol Noshirvani University of Technology
چکیده English

In the present study, using a new method, dual-phase (DP) steel with high strength and good ductility was produced from plain carbon steel with 0.16% carbon. The DP steel with ferrite-martensite structure was obtained using austenitizing, quenching, asymmetric cold rolling, and intercritical annealing at temperatures of 770 and 800 °C and short holding times of 1 and 5 min. Due to the application of uniform shear strain through asymmetric cold rolling, a uniform distribution of the martensite phase was observed in the RD-TD and RD-ND planes. By increasing the holding time, the volume fraction of martensite increased from 8% to 12% at 770 °C and from 10% to 33% at 800 °C for the holding times of 1 and 5 min, respectively. Hardness and strength improved with increasing temperature and time of intercritical annealing. The sample produced at a temperature of 800 °C and a time of 5 minutes showed excellent mechanical properties such as 244 HV hardness and 1020 MPa strength and 12.5% ​​ductility. In addition, due to the high volume fraction of martensite and the consequent reduction of its carbon content, the hardness of this phase decreased and as a result, it showed significant plastic deformation and high strain hardening. The fracture surface of all produced DP steels mainly included dimples, which indicates ductile fracture behavior.

کلیدواژه‌ها English

Dual-Phase Steel
Asymmetric rolling
Intercritical annealing
Microstructure
Mechanical properties
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