Sünek dökme demirde çentik mukavemet oranının çoklu doğrusal regresyon modeli ile tahmini

Abstract

Bu çalışmada, alaşımlı sünek dökme demirde matris yapısı ve çentik kök yarıçapının çentik mukavemet oranına olan etkisi çoklu doğrusal regresyon analizi ile incelenerek bir model oluşturulması hedeflenmiştir. Bu amaçla, dökme demirde ferritik, perlitik/ferritik, perlitik, temperlenmiş martensitik, alt beynitik ve üst beynitik matris yapıları elde etmek için çeşitli ısıl işlemler uygulanmıştır. Matris yapıların sertliğini ve 0,2 akma dayanımını belirlemek için sertlik ve çekme testleri uygulanmış ve bunlar regresyon analizinde bağımsız değişkenler olarak ele alınmıştır. Ayrıca, 0,05-0,8 mm çentik kök yarıçapı aralığına sahip çevresel V çentikli numuneler üzerinde çekme testleri uygulanmış ve elde edilen çentikli çekme dayanımları regresyon analizinde üçüncü bağımsız değişken olarak kullanılmıştır. Sertlik, 0,2 akma dayanımı ve çentik kök yarıçapı bağımsız değişkenleri ile çentik mukavemet oranını tahmin etmek için çoklu regresyon analizi yardımıyla bir model geliştirilmiştir. Analiz sonucunda, 0,886 değerinde ayarlanmış bir R2 değeri elde edilmiştir. Bu sonuç, tahmin edilen çentik mukavemet oranı değerlerinin %88,6'sının sertlik, 0,2 akma dayanımı ve çentik kök yarıçapı ile değiştirilebileceğini açıklamaktadır. Elde edilen model ile, matris yapılarda yalnızca minimal farklar sergileyen tatmin edici çentik mukavemet oranları öngörülmüştür.

Keywords

• Sünek dökme demir
• matris yapı
• regresyon analizi
• çentik mukavemet oranı.

Prediction of notch strength ratio of a notched tensile ductile iron using multiple linear regression model

Abstract

This study aims to create a model by examining the effect of the matrix structure and notch root radius on the notch strength ratio (NSR) in an alloyed ductile cast iron through multiple linear regression analysis. For this purpose, several heat treatments were applied to obtain ferritic, pearlitic/ferritic, pearlitic, tempered martensitic, lower bainitic, and upper bainitic matrix structures in cast iron. Hardness and tensile tests were applied to determine the hardness and 0.2 yield strength of matrix structures, which were then considered independent variables in the regression analysis. Additionally, tensile tests were conducted on circumferentially V-notched samples with a notch root radius range of 0.05-0.8 mm, and the notch radius was used as the third independent variable in the analysis. A model was developed by multiple regression to predict the NSR with the aid of the hardness, 0.2 yield strength, and notch radius independent variables. The analysis had an adjusted R2 value of 0.886, which explains that 88.6 % of predicted NSR values can be varied by the hardness, 0.2 yield strength, and notch root radius. The model predicted satisfactory NSR values in matrix structures, exhibiting only minimal residuals.

Keywords

• Ductile iron
• matrix structure
• regression analysis
• notch strength ratio.

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