The Effect on Retained Austenite Volume Fraction of Sample Preparation Processes in Water Quenched AISI 52100 Steel

Abstract

Sample preparation is one of the main steps in metallographic examinations and the sample preparation processes give rise to changes in the determination of volume fraction of any phases can cause to failure at the interpretation of a study. In this study, effect of applied load during metallographic sample preparation process on the volume fraction of retained austenite of the water quenched AISI 52100 was investigated. Metallographic examination samples were prepared under different loads (20N, 40N, 80N, 100N) were examined by optical and SEM microscopes. The retained austenite volume fraction was calculated by direct comparison method from the XRD analysis. Surface roughness was determined via a profilometer in order to reveal the effect of surface roughness on XRD patterns. Hardness measurements were performed to determine the probability of applied load that may transform retained austenite into martensite and rise in macro hardness after this transformation. No significant phase transformation was observed in the retained austenite phase volume fraction of metallographic examination samples prepared under different loads on retained austenite volume fraction measurements by the XRD method and. It is thought that a large amount of martensite volume fraction applies compressive stress on the retained austenite owing to low retained austenite volume fraction (<%10) is the reason for not being observed phase transformation.

Keywords

• AISI 52100 steel,Volume Fraction of Retained Austenite,XRD,Metallographic Sample Preparation

Su Verilmiş AISI 52100 Çeliğinde Metalografik Numune Hazırlama İşlemlerinin Kalıntı Östenit Hacim Oranına Etkisi

Öz

Metalografik incelemelerde numune hazırlama işlemleri malzeme karakterizasyonunda temel basamaklardan biri olup, numune hazırlama işlemlerinin mikroyapıyı oluşturan fazların kararlılığında değişkenliğe sebebiyet vermesi yapılan deneysel çalışmanın yorumlanmasında hatalara neden olabilmektedir. Bu çalışmada, su verilmiş AISI 52100 çeliğinde metalografik numune hazırlama işlemlerinde (zımpara+polisaj) uygulanan yükün kalıntı östenit hacim oranına etkisi araştırılmıştır. Farklı yükler (20N, 40N, 80N, 100N) altında hazırlanan numuneler optik mikroskop, SEM ile incelenmiş ve XRD analizleri yapılmıştır. Kalıntı östenit miktarı XRD analizinin doğrudan karşılaştırılması yöntemiyle hesaplanmıştır. Yüzey pürüzlülüğünün XRD desenlerine etkilerini belirlemek amacıyla yüzey pürüzlülüğü ölçümleri yapılmıştır. Uygulanan yükün kalıntı östeniti martensite dönüştürme ve bu dönüşüm sonrasında makro sertlikte artış ihtimalini değerlendirmek amacıyla sertlik ölçümleri gerçekleştirilmiştir. Bu çalışmalar sonucunda farklı yükler altında hazırlanan metalografi inceleme numunelerinin optik mikroskop, SEM ile mikroyapı incelemeleri ve XRD analizleri kalıntı östenit hacim oranında dikkate değer bir farklılığın oluşmadığını göstermiştir. Kalıntı östenit faz hacim oranında değişimin gözlemlenmemesinin sebebi olarak kalıntı östenit hacim oranının az olması (<%10) sebebiyle fazla miktardaki martenzit hacim oranının östenit üzerine uyguladığı yüksek basma gerilmesi olduğu düşünülmektedir.

Anahtar Kelimeler

• AISI 52100 çeliği,Kalıntı Östenit Hacim Oranı,XRD,Metalografik Numune Hazırlığı

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