Ferritik Çeliklerde Kırılma Tokluğunun Saptanmasında Farklı Bir Yaklaşım

Year 2020, Volume: 10 Issue: 4, 887 - 899, 15.10.2020

Halil Aytekin , Yelda Akçin , Melih Özçatal

https://doi.org/10.17714/gumusfenbil.704032

Abstract

Günümüzde, malzeme seçimi, geleneksel olarak malzemenin akma
dayanımına göre yapılmaktadır. Ancak burada, parça dizaynı veya geometrik
unsurlardan kaynaklanan gerilim konsantrasyonları dikkate alınmamaktadır. Bu
şartların değerlendirilmesi, sadece malzemenin kırılma tokluğu ile mümkündür.
Kırılma tokluğunun saptanmasında, metalik malzemeler için, ASTM E-399 standardı
geliştirilmiştir. Bu standart uyarınca, düzlemsel deformasyon durumuna (gevrek
kırılma) uygun olarak hazırlanmış olan numuneler test edilir. Özellikle
ferritik çeliklerde, bu durum büyük boyutlu numuneler üzerinde deney
yapılmasını gerektirir ve böylece söz konusu çeliklerin kırılma tokluğunun
saptanması zorlaşır. Bununla birlikte, bazı alternatif yöntemler
geliştirilmiştir. Başlıca yöntemler, J-İntegral ve COD yöntemleridir.
J-İntegral yönteminin yüksek toleransının sınır şartlarını belirlemek için ASTM
E-1921 standardı geliştirilmiş ve Master Curve (MC) kavramı ortaya atılmıştır.
Bu yöntemlerin olumsuz yanı, oldukça yüksek tolerans göstermesidir. Bu çalışmada,
kırılma tokluğunun saptanmasında yeni bir yöntem incelenmiş ve literatürde yapılmış
çalışmalar derlenerek, yeni bir yaklaşım ile yöntemin geliştirilmesi
amaçlanmıştır.

Keywords

Akma Dayanımı, ASTM E1921 Standardı, ASTM E399 Standardı, Kırılma Tokluğu

Supporting Institution

Afyon Kocatepe Üniversitesi

Project Number

17.TEKNOLOJİ.02

Thanks

Bu çalışma, 17.TEKNOLOJİ.02 proje numarası ve “Ferritik Çeliklerde Kırılma Tokluğunun Saptanmasında Farklı Bir Yaklaşım” ismiyle Afyon Kocatepe Üniversitesi Bilimsel Araştırma Projeleri Koordinasyonu (BAPK) tarafından desteklenmiştir.

A Different Approach to the Determination of the Fracture Toughness in Ferritic Steels

Abstract

Nowadays, the material
selection is conventionally made according to the yield strength of the
material. However, stress concentrations from geometric factors or component
design are not considered. The evaluation of these conditions is only possible
with fracture toughness of the materials. ASTM E-399 has been developed for the
determination of fracture toughness of the metallic materials. According to
this standard, samples suitable to the plane deformation (brittle fracture) are
tested. Especially in ferritic steels, this condition requires testing on
large-sized samples, and thus, it is difficult to determine the fracture
toughness of these steels. However, some alternative methods have been
developed into this standard. The major methods are J-integral and COD methods.
ASTM E-1921 standard was developed in order to determine the boundary
conditions of the high tolerance of J-integral method, and Master Curve (MC)
concept was proposed. The disadvantage of these methods is that they show quite
high tolerance. In this study, a new method has been investigated in the
determination of the fracture toughness. The similar studies in the literature
have been compiled, and developing of the method with a new approach was
purposed.

Keywords

Yield Strength, ASTM E1921 Standards, ASTM E399 Standards, Fracture Toughness

Project Number

17.TEKNOLOJİ.02

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