Investigation of Weldability of 25% Recycled Al6016 Series Sheet Metal Materials Used in Automotive by Friction Stir Spot Welding

Abstract

In this study, joint samples were obtained from 2 mm thick Al6016 (AL6-HDI-TZ-U) series sheets produced with a recycling rate of 25%. A special fixture was designed for the test samples and integrated into the universal mold milling machine and joints were made. The joint tool tip geometry was selected as 2379 material with a 10-degree conical, 2.9 mm height, and 15 mm shoulder diameter and the surface hardness was increased to 62-65 HRC. The welding waiting time was kept constant as 4 s. The joints were made by friction stir spot welding at 6 different speeds as 600, 1200, 1800, 2400, 3000, 3600 rpm. The heat inputs of the jointed test sample connections were calcu-lated and hardness test, tensile shear test and macro and microstructural analyzes were examined. The joints made at speeds of 600, 1200, 1800, 2400, 3000, 3600 rpm were successful, the finest grain structure was found in the SZ region and the coarsest grain structure was found in the HAZ region at all speeds. The highest tensile shear load was observed as Rm:109 MPa at 600 rpm. The highest hardness values were determined as 108 ± 2, 101 ± 3, 95 ± 3 and 87 ± 5 HV0,1 for BM, SZ, TMAZ and HAZ at 600 rpm, respectively. Brittle fracture mode was observed in joints at speeds of 600 and 1200 rpm, while ductile fracture mode was observed at other speeds. The joining zone was defined as the dynamically recrystallising stir zone (SZ), thermo-mechanically af-fected zone (TMAZ), heat-affected zone (HAZ) and base metal (BM).

Keywords

• Al6016
• friction stir spot welding
• recycled material
• C2379

Otomotivde Kullanılan %25 Geri Dönüştürülmüş Al6016 Serisi Sacların Sürtünme Karıştırma Nokta Kaynağı ile Birleştirilebilirliğinin İncelenmesi

Abstract

Bu çalışmada, geri dönüştürülme oranı %25 olarak üretilen 2 mm kalınlığındaki Al6016 (AL6-HDI-TZ-U) serisi saclardan birleştirme numuneleri elde edilmiştir. Test numuneleri için özel fikstür tasarlanarak üniversal kalıpçı freze tezgahına entegre edilmiştir ve birleştirmeler yapılmıştır. Birleştirici takım ucu geometrisi 10 derece konik, yüksekliği 2.9 mm, omuz çapı 15 mm olacak şekilde 2379 malzeme olarak seçilmiş ve yüzey sertliği 62-65 HRC’ye çıkartılmıştır. Kaynak bekleme süresi 4 sn olarak sabit tutulmuştur. Birleştirmeler 600, 1200, 1800, 2400, 3000, 3600 rpm olarak 6 farklı devirde sürtünme karıştırma nokta kaynağı yapılmıştır. Birleştirilen test numune bağlantılarının ısı girdileri hesaplanarak sertlik testi, çekme kesme testi ile makro ve mikroyapısal analizleri incelendi. 600, 1200, 1800, 2400, 3000, 3600 rpm hızlarda yapılan birleştirmeler başarılı oldu, tüm hızlarda SZ bölgesinde en ince tane yapısı, HAZ bölgesinde en kalın tane yapısı olduğu tespit edilmiştir. 600 rpm de en yüksek çekme kesme yükünü Rm:109 MPa olarak görüldü. En yüksek sertlik değer-leri, 600 rpm'de BM, SZ, TMAZ ve HAZ için sırasıyla 108 ± 2, 101 ± 3, 95 ± 3 ve 87 ± 5 HV0,1 olarak tespit edildi. 600 ve 1200 rpm hızlardaki birleştirmelerde gevrek, diğer hızlarda sünek kırılma modu görülmüştür. Birleştirme bölgesi, dinamik olarak yeniden kristalleşen karıştırma bölgesi (SZ), termo-mekanik olarak etkilenen bölge (TMAZ), ısıdan etkilenen bölge (HAZ) ve ana metal (BM) olarak tanımlanmıştır.

Keywords

• Al6016
• sürtünme karıştırma nokta kaynağı
• geri dönüştürülmüş malzeme
• C2379

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