DP800 çeliğinin ılık sıcaklık U eğme prosesinde geri esneme ve şekillendirme sonrası mekanik özelliklerinin incelenmesi

Abstract

Geri esneme, şekillendirilmiş ürünlerin montajı sırasında sorunlara yol açması ve zaman ve enerji kaybına yol açması nedeniyle bükme işleminin en istenmeyen sonuçlarından biridir. Bükme işleminden önce sac metali ısıtmak, geri yaylanmanın istenmeyen etkilerini hafifletmek için endüstride yaygın olarak kullanılan bir uygulamadır. Ancak, birçok durumda, sıcak veya ılık bükme işleminin bükülmüş ürünlerin mekanik özellikleri üzerindeki sonuçları tam olarak dikkate alınmamaktadır. Bu çalışmada, sıcak bükme işleminde, baskı plaka kuvveti ve yağlama gibi proses parametrelerinin DP800 çeliğinin geri yaylanma davranışı üzerindeki etkileri incelenmiştir. Ayrıca, bükülmüş numunelerin şekillendirme sonrası mekanik özellikleri araştırılmıştır. Bunun için, DP800 çelik saclar dört farklı sıcaklıkta (25 "℃", 200 "℃", 300 "℃", 400 "℃"), üç farklı baskı plaka kuvveti (25bar, 75bar, 125 bar) ve iki farklı yağlayıcı (grafit ve teflon) kullanılarak şapka biçiminde bükülmüştür. Elde edilen sonuçlara göre, baskı plaka kuvvetinin azaltılması ve daha iyi bir yağlayıcı (teflon) uygulanmasının daha düşük bir geri esneme elde etmede önemli bir etkiye sahip olduğu anlaşılmıştır. Ek olarak, sıcaklığın artırılması geri esnemeyi olumlu etkilerken, ılık sıcaklıklarda bükülmüş sacların şekillendirme sonrası mukavemetlerinin önemli bir azalma göstermediği görülmüştür.

Keywords

• Geri esneme, DP800,
• Ilık şekillendirme
• Geliştirilmiş Yüksek Mukavemetli Çelik
• U-bükme

Project Number

2021.06.05.1178

Evaluation of Springback and Post-Formed Mechanical Properties of DP800 Steel in Warm-Hat-Shaped Bending Process

Abstract

Springback is one of the most undesired outcomes of a bending process since it creates problems during the assembly of formed products and leads to waste time and energy. Heating the sheet metal before the bending process is an application that is widely used in the industry to alleviate the undesired effects of springback. However, in many cases, the consequences of a warm or hot bending process on the mechanical properties of bent products are not thoroughly considered. In this study, the effects of the warm bending process combined with the process parameters such as blank-holder force and lubrication on the springback behaviour of DP800 steel have been examined. Additionally, the post-mechanical properties of the bent specimens have been investigated. For this, sheets of DP800 steels have been bent to a hat-shaped product at four different temperatures (25 ℃, 200 ℃, 300 ℃, 400 ℃), by using three different blank-holder force (25bar, 75bar, 125 bar), and two different lubricants (graphite and teflon). According to the results, it has been shown that reducing the blank-holder force and applying a better lubricant (teflon) has had a considerable effect in attaining a lower springback. Additionally, while increasing the temperature has positively impacted the springback, it has been found that the post-mechanical strength of bent sheets at warm temperatures has not shown a significant reduction.

Keywords

• Springback
• DP800
• Warm forming
• Advanced high strength steels
• Hat-shaped bending

Supporting Institution

Any external funding or organizational support received for the study should be detailed here. If the study received no external funding, it can be stated as: “This research received no external funding.”

Project Number

2021.06.05.1178

Ethical Statement

This study does not involve human or animal participants. All procedures followed scientific and ethical principles, and all referenced studies are appropriately cited.

Thanks

For this work, the authors gratefully acknowledge the financial support provided by the Duzce University Research Fund [Project No: 2021.06.05.1178].

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