The Research Committee Report on Evaluation of Delayed Fracture Properties for Spring Steels Second Activity Part 1 —Maximum Diffusible Hydrogen in Actual Environment and Standardizing Chemical Analysis Method of Hydrogen—

Abstract

Though there are many activities to define delayed fracture method by professors, professional engineer and any specialists, there is still no standardized delayed fracture test method, and Automotive OEMs have their own ideas and test methods for reasons of the above. Considering background of the recent high hardness spring design, we need to prepare standardized test method to prevent delayed fracture risk in the future. Therefore, the research committee have been in action to standardize delayed fracture test method simulated automotive environment. The issues to be solved are as bellows, First issue is to establish hydrogen analysis method to separate hydrogen occurred in the rust remained on material surface.

Second issue is to estimate maximum hydrogen content entered from automotive environment.

Third issue is to confirm an evaluation method to occur delayed fracture by grasping the coil spring simulated fracture pattern in the market.

4th issue is to establish an evaluation method used test piece to be reproduced fracture pattern in the market.

This study reports experiment results for the first and second issues as in September 2019.