Research on Hardness for Low-Alloy Steel after Fire Damage

Abstract

In chemical processing plants and petroleum refineries, the pressure vessels and pipelines suffered often from fire accidents and thus resulted in the metal materials were in overheating state. Elevated temperature could cause the changes in metallographic structure and have unfavorable effects on material mechanical properties. In order to understand better the influence laws of overheating on metallographic structures and material mechanical properties, the methods of theoretical analysis and experimental research were used and the effects of thermal exposure temperature, duration time and cooling rate on microstructure and mechanical properties of low-alloy steel 12MnNiVR, were studied systematically. In the paper, mechanical testing (hardness test) are carried out to understand changes in the mechanical properties that would be observed in the metal exposed to elevated temperatures during a fire accident. The study can provide basis data for the material properties database of metal material suffered from fire accident, and afford technical supports in the key technologies on fire damage FFS (Fitness-For-Service) integrity assessment.