اثر فرآیند مارتمپرینگ پله ای و ناهمسانگردی بر میزان تابیدگی و اعوجاج فولاد ابزارگرم کار نورد سرد شده

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانش آموخته کارشناسی ارشد دانشگاه آزاد کرج - مهندس شرکت مالیبل سایپا

2 دانشیار دانشکده مهندسی مواد دانشگاه علم و صنعت ایران

3 استادیار گروه مهندسی مواد و متالورژی دانشکده فنی و مهندسی-دانشگاه اراک

چکیده

در این تحقیق نقش ناهمسانگردی ساختاری ناشی از نورد سرد بر میزان تابیدگی و اعوجاج یک فولاد ابزار گرم کار مورد استفاده در قالب سازی قبل و بعد از عملیات حرارتی سخت کاری مورد مطالعه واقع شد. برای عملیات سخت کاری از فرآیند مارتمپرینگ پله ای استفاده شد. میزان تابیدگی در سه وضعیت شامل پس از ماشین کاری، پس از تنش گیری و پس از مارتمپرینگ از طریق فاکتور تختی مورد سنجش واقع شد. به منظور بررسی تاثیر ناهمسانگردی بر میزان اعوجاج فولاد، بسته به جهت نورد نمونه هایی در سه وضعیت هندسی تهیه شدند. میزان تابیدگی در نمونه ها قبل از مارتمپرینگ بسیار ناچیز و تابع جهت گیری نمونه ها نبوده و یک خاصیت همسانگرد می باشد. نتایج نشان داد که انجام مارتمپرینگ موجب اعوجاج فولاد شده و این تابیدگی بسته به هندسه نمونه برداری متفاوت است که مبین آن است که تابیدگی در فولاد سخت شده یک خصوصیت ناهمسانگرد است. کمترین اعوجاج مربوط به نمونه هایی بود که عمود بر جهت نورد تهیه شده بودند. اندازه گیری سختی نمونه ها نشان داد که برخلاف تابیدگی، سختی قبل و بعد از سخت کاری یک ویژگی همسانگرد و مستقل از جهت نمونه برداری است.

کلیدواژه‌ها


عنوان مقاله [English]

Influence of the Step Martempering and Anisotropy on the Distortion Value a Cold Rolled Hot Work Tool Steel

نویسندگان [English]

  • Jamaleddin Fereshtekheslat 1
  • Seyed hossein Razavi 2
  • ashkan nouri 3
3 Assistant professor- department of materialas science and metallurgy-Arak university
چکیده [English]

In this investigation, the role of the structural anisotropy due to cold rolling on the distortion value of hot work tool steel employing in moulding before and after the hardening heat treatment was studied. For the hardening treatment, was used a step martempering process. Distortion amount was calculated by flatness factor in 3 states; after machining, after stress relief treatment and after martempering. For purpose of the consideration of the anisotropy effect on the steel distortion, were prepared samples dependent on the rolling direction in 3 geometrical states. Before martempering, the distortion value of the samples is very low and negligible. It is also independent on the sampling direction. Thus it is an isotropic characteristic. Results revealed that distortion is induced in the martempered steel. It is also significantly different in various directions of sampling. It is implied that in the hardened steel, distortion is an anisotropic property. The lowest distortion is belonging to sample which is perpendicular to the rolling direction. Hardeness measurement showed that this specification is an isotropic property in both before and after hardening and is not affected by the geometrical direction of sampling.

کلیدواژه‌ها [English]

  • Heat treatment
  • Martempering
  • Distortion
  • Structural anisotropy
  • Flatness

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