Grain Size Effect on Crack Nucleation and Growth in Long-Life Fatigue of Low-Carbon Steel

2009 ◽  
pp. 135-135-39 ◽  
Author(s):  
S Taira ◽  
K Tanaka ◽  
M Hoshina
Keyword(s):  
Grain Size ◽  
Carbon Steel ◽  
Size Effect ◽  
Crack Nucleation ◽  
Low Carbon Steel ◽  
Nucleation And Growth ◽  
Grain Size Effect ◽  
Low Carbon ◽  
Long Life ◽  
Crack Nucleation And Growth

scholarly journals Effect of Carbon Partitioning, Carbide Precipitation, and Grain Size on Brittle Fracture of Ultra-High-Strength, Low-Carbon Steel after Welding by a Quenching and Partitioning Process

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 747 ◽  
Author(s):  
Farnoosh Forouzan ◽  
M. Guitar ◽  
Esa Vuorinen ◽  
Frank Mücklich
Keyword(s):  
Grain Size ◽  
Carbon Steel ◽  
Weld Zone ◽  
Low Carbon Steel ◽  
High Strength ◽  
Precipitate Size ◽  
Low Carbon ◽  
Quenching And Partitioning ◽  
High Level ◽  
The Impact

To improve the weld zone properties of Advanced High Strength Steel (AHSS), quenching and partitioning (Q&P) has been used immediately after laser welding of a low-carbon steel. However, the mechanical properties can be affected for several reasons: (i) The carbon content and amount of retained austenite, bainite, and fresh martensite; (ii) Precipitate size and distribution; (iii) Grain size. In this work, carbon movements during the partitioning stage and prediction of Ti (C, N), and MoC precipitation at different partitioning temperatures have been simulated by using Thermocalc, Dictra, and TC-PRISMA. Verification and comparison of the experimental results were performed by optical microscopy, X-ray diffraction (XRD), Scanning Electron Microscop (SEM), and Scanning Transmission Electron Microscopy (STEM), and Energy Dispersive Spectroscopy (EDS) and Electron Backscatter Scanning Diffraction (EBSD) analysis were used to investigate the effect of martensitic/bainitic packet size. Results show that the increase in the number density of small precipitates in the sample partitioned at 640 °C compensates for the increase in crystallographic packets size. The strength and ductility values are kept at a high level, but the impact toughness will decrease considerably.

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