On the application of the forming limit diagrams for quality control of blanks for wheelbarrow of ASTM A1008 carbon steel

Abstract

The effectivity of the forming limit diagrams in manufacturing wheelbarrow by deep-drawing is shown because of the high material scrap rate which reduces productivity. Several chemical, mechanical testing and microstructural analysis were performed to examine sheet quality and their impact on these diagrams. Chemical analysis revealed that Steel 1 and Steel 3 sheets fulfilled the specification without assuring adequate forming process. However, the higher titanium content of Steel 2 improved its formability since it promoted the formation of fine precipitates, thus refining the grain size. This steel had the highest ASTM grain size number G (9.11), which is the lowest average grain size (13 µm) compared to the other steels, which had G values in the range 8.7 to 9.11. Moreover, Steel 2 sheets had the greatest plastic strain ratio (rm = 1.80), the highest strain-hardening exponent (n = 0.250), the lowest anisotropy ∆r = 0.31), yielding better results in deep-drawing strain distribution, the highest forming limit strain (28%) and the highest uniform elongation zone, favoring that failure sites did not occur.

Keywords

• ASTM A1008 carbon steel
• Forming limit diagram
• Plastic strain ratio
• Quality control
• Strain-hardening exponent