Effects of Different Dissolution and Aging Heat Treatments on Metallographic and Mechanical Properties of NiTi Based Sheets

Sinan Aksöz; Rıdvan Arslan; Nimet Kardeş Sever; Bülent Bostan

Makale detayları

Effects of Different Dissolution and Aging Heat Treatments on Metallographic and Mechanical Properties of NiTi Based Sheets

Yazarlar:

Sinan Aksöz | Rıdvan Arslan | Nimet Kardeş Sever | Bülent Bostan

Yayıncı:

Gazi University

Ana Başlıklar:

Mühendislik

Dergi:

Politeknik Dergisi Vol.26 Issue 2, pp.693-700

Belge Tipi:

Makale

Yayın Tarihi:

5/2023

Belge Dili:

Türkçe

Document ID (Org No.):

2001295579

pISSN:

2147-9429

Anahtar kelimeler:

Özet:

 In this study; 1-mm-thick NiTi sheets showing phase transformation at 45ºC and 80ºC were used. First, three-point bending tests were performed to investigate the bendability. Later, solution heat treatments were applied to the samples taken from the bent sheets for 1 hour at 750ºC, 800ºC, 850ºC and 900ºC respectively. Aging heat treatment was applied for 15, 30, 45, 60, 75 and 90 minutes min. at 300ºC to these samples. Optical Microscope, Field Emission Scanning Electron Microscopy FESEM, Element Dispersion Spectroscopy EDS and MAPPING MAP analyses were carried out to examine the effects of the heat treatment parameters. Macro hardness data were taken to examine the mechanical effects after each heat treatment. Moreover, the mechanical behavior of the material under load was investigated by Dynamic Mechanical Analyses DMA. As a result, mechanical properties hardness and storage modulus have been improved by aging heat treatments. The highest hardness value was measured as 414HV after solution heat treatment at 900ºC and aging heat treatment at 300ºC for 75 minutes on the sample showing phase transformation at 80ºC. Furthermore, an increase in storage modulus and a decrease in tanδ value occurred. To benefit from super elastic properties of NiTi alloys, the necessity of using temperatures above the transformation temperatures was observed with the storage modulus measurements. Storage modulus value under transformation temperature was 21500MPa while it was measured as 28500MPa after the transformation was completed for the sample with 45C transformation temperature.

 In this study; 1-mm-thick NiTi sheets showing phase transformation at 45ºC and 80ºC were used. First, three-point bending tests were performed to investigate the bendability. Later, solution heat treatments were applied to the samples taken from the bent sheets for 1 hour at 750ºC, 800ºC, 850ºC and 900ºC respectively. Aging heat treatment was applied for 15, 30, 45, 60, 75 and 90 minutes min. at 300ºC to these samples. Optical Microscope, Field Emission Scanning Electron Microscopy FESEM, Element Dispersion Spectroscopy EDS and MAPPING MAP analyses were carried out to examine the effects of the heat treatment parameters. Macro hardness data were taken to examine the mechanical effects after each heat treatment. Moreover, the mechanical behavior of the material under load was investigated by Dynamic Mechanical Analyses DMA. As a result, mechanical properties hardness and storage modulus have been improved by aging heat treatments. The highest hardness value was measured as 414HV after solution heat treatment at 900ºC and aging heat treatment at 300ºC for 75 minutes on the sample showing phase transformation at 80ºC. Furthermore, an increase in storage modulus and a decrease in tanδ value occurred. To benefit from super elastic properties of NiTi alloys, the necessity of using temperatures above the transformation temperatures was observed with the storage modulus measurements. Storage modulus value under transformation temperature was 21500MPa while it was measured as 28500MPa after the transformation was completed for the sample with 45C transformation temperature.

 In this study; 1-mm-thick NiTi sheets showing phase transformation at 45ºC and 80ºC were used. First, three-point bending tests were performed to investigate the bendability. Later, solution heat treatments were applied to the samples taken from the bent sheets for 1 hour at 750ºC, 800ºC, 850ºC and 900ºC respectively. Aging heat treatment was applied for 15, 30, 45, 60, 75 and 90 minutes min. at 300ºC to these samples. Optical Microscope, Field Emission Scanning Electron Microscopy FESEM, Element Dispersion Spectroscopy EDS and MAPPING MAP analyses were carried out to examine the effects of the heat treatment parameters. Macro hardness data were taken to examine the mechanical effects after each heat treatment. Moreover, the mechanical behavior of the material under load was investigated by Dynamic Mechanical Analyses DMA. As a result, mechanical properties hardness and storage modulus have been improved by aging heat treatments. The highest hardness value was measured as 414HV after solution heat treatment at 900ºC and aging heat treatment at 300ºC for 75 minutes on the sample showing phase transformation at 80ºC. Furthermore, an increase in storage modulus and a decrease in tanδ value occurred. To benefit from super elastic properties of NiTi alloys, the necessity of using temperatures above the transformation temperatures was observed with the storage modulus measurements. Storage modulus value under transformation temperature was 21500MPa while it was measured as 28500MPa after the transformation was completed for the sample with 45C transformation temperature.

 Bu çalışmada 45ºC ve 80ºCde faz dönüşümü gösteren 1 mm kalınlığında NiTi saclar kullanılmıştır. Öncelikle, eğilebilirliği incelemek için üç nokta eğme testleri yapılmıştır. Bundan sonra bükülmüş saclardan alınmış numunelere sırasıyla; 750ºC, 800ºC, 850ºC ve 900ºCde 1 saat çözündürme ısıl işlemleri uygulanmıştır. Bu numunelere sırası ile 300ºCde 15, 30, 45, 60, 75 ve 90 dakika dk. süreyle yaşlandırma ısıl işlemi uygulanmıştır. Isıl işlem parametrelerinin etkilerini incelemek için Optik Mikroskop, Alan Emisyon Taramalı Elektron Mikroskobu FESEM, Element Dağılım Spektrometresi EDS ve Haritalama MAP analizleri gerçekleştirilmiştir. Mekanik etkileri incelemek için her bir ısıl işlemden sonra makro sertlik verileri alınmıştır. Ayrıca Dinamik Mekanik Analiz DMA ile malzemenin yük altındaki mekanik davranışı incelenmiştir. Sonuç olarak, yaşlandırma ısıl işlemi sayesinde mekanik özellikler sertlik ve depolama modülü iyileştirilebilmiştir. En yüksek sertlik değeri, 80C dönüşüm sıcaklığına sahip numunede, 900Cde çözündürme ve 300Cde 75 dk. yaşlandırma sonrası 414HV olarak ölçülmüştür. Ayrıca, depolama modülünde artış, tanδ değerinde ise düşüş meydana gelmiştir. NiTi alaşımlarının süper elastik özelliklerinden faydalanabilmek için, dönüşüm sıcaklıklarının üzerindeki sıcaklıkların kullanılması gerekliliği depolama modülü ölçümleri ile görülmüştür. 45C dönüşüm sıcaklığına sahip numune için dönüşüm sıcaklığı altında depolama modül değeri 21500MPa iken dönüşüm tamamlandıktan sonra  28500MPa olarak ölçülmüştür.

Makale detayları

Effects of Different Dissolution and Aging Heat Treatments on Metallographic and Mechanical Properties of NiTi Based Sheets

Yazarlar:

Sinan Aksöz | Rıdvan Arslan | Nimet Kardeş Sever | Bülent Bostan

Yayıncı:

Gazi University

Ana Başlıklar:

Mühendislik

Dergi:

Politeknik Dergisi Vol.26 Issue 2, pp.693-700

Belge Tipi:

Makale

Yayın Tarihi:

5/2023

Belge Dili:

Türkçe

Document ID (Org No.):

2001295579

pISSN:

2147-9429

NiTi alloys

heat treatment

hardness

storage modulus

microstructureNiTi alaşımlar

ısıl işlem

sertlik

depolama modülü

mikroyapı

Sayı

Makale detayları

Yazarlar: Sinan Aksöz | Rıdvan Arslan | Nimet Kardeş Sever | Bülent Bostan

Yayıncı: Gazi University

Ana Başlıklar: Mühendislik

Dergi: Politeknik Dergisi Vol.26 Issue 2, pp.693-700

Belge Tipi: Makale

Yayın Tarihi: 5/2023

Belge Dili: Türkçe

Document ID (Org No.): 2001295579

pISSN: 2147-9429

Sayı

Yazarlar:

Sinan Aksöz | Rıdvan Arslan | Nimet Kardeş Sever | Bülent Bostan

Yayıncı:

Gazi University

Ana Başlıklar:

Mühendislik

Dergi:

Politeknik Dergisi Vol.26 Issue 2, pp.693-700

Belge Tipi:

Makale

Yayın Tarihi:

5/2023

Belge Dili:

Türkçe

Document ID (Org No.):

2001295579

pISSN:

2147-9429