| Abstract Scope |
Introduction:
A variety of unintended factors influence the results of Charpy V-notch impact testing of steels. A few of these factors consist of the stability of the pendulum foundation, placement of the sample before impact, consistency in the location of the notch, and the condition of the pendulum. Although little research has been conducted on the implications of notching methods, it is an essential factor that warrants investigation. Notching causes localized plastic deformation, which can potentially affect impact energy results. Geometric inconsistencies within the notch may also influence the final toughness, particularly from sample to sample. It is currently unknown whether specific notching methods cause more plastic deformation or geometrical inconsistencies than others. Even if it is assumed that the notching method affects the impact energy readings, it is crucial to determine how much the average impact energy varies between each technique. The objective is to discover which notch creation method for Charpy V-notch minimizes general inaccuracy while maximizing consistency between notches made using the same process. The industry goal of comparing various notching methods is to identify the optimal strategy for notching specimens, particularly minimizing sample-to-sample variance.
Experimental Procedures:
Low carbon steel bars were used for the Charpy V-notch impact testing, specifically AISI 1018, with a carbon content of 0.08 weight percent and a Brinell hardness number of 172. The bars were sectioned and machined to meet the ASTM E-23 criteria for Charpy V-notch sample dimensions, and only one surface of each block was machined while the rest remained in the as-received rolled condition. The samples were stored in a dry environment among desiccants before, during, and after notching until testing. Industrial participants were asked to notch the samples using their most commonly used method, and the notches were created on the machined side to avoid adding the influence of a machined surface. Each organization's individual method was followed to maintain consistency in notching. The methods investigated were grinding, machining, electrical discharge machining, and broaching. Thirty samples were notched using each method and then sent back for testing. The notch surfaces were analyzed and imaged before being broken, and any geometric inconsistencies were documented using a Keyence VHX-7000N 4K Ultra-High Accuracy Digital Microscope and ZeGage plus 3D Optical Profiler. An Instron CEAST 9350 drop tower with the standard 8mm tup radius was used to break the specimens, and the impact testing was performed at room temperature with a loading rate programmed to be the same as using the standard pendulum. The test procedure was measured using an optical encoder to record velocity and a load cell to measure force. CEAST's data acquisition system captured real-time data, and impact energy was automatically calculated based on force-displacement measurements. Post-test fracture surfaces were analyzed using the microscope and profilometer. The amount of plastic strain experienced by the samples was determined by measuring the difference in their dimensions before and after breaking. The final impact data set underwent statistical analysis, which included evaluating both the overall impact data and the variance between notch data.
Results and Discussion/Conclusion:
To be determined. Once the results are in, I will send an updated abstract containing the Results and Discussion, and Conclusion sections.
Keywords:
Charpy V-notch, Impact Energy, Plastic Deformation, Manufacturing Methods, Low Carbon Steel, Industrial Standards, Mechanical Testing |