EFFECT OF CARBON ON THE TOUGHNESS AND FRACTURE MODE OF Fe-P ALLOYS.

Abstract

Charpy impact tests hardness measurements, optical and transmission electron microscopy were performed on alloys (P, 0. 05, 0. 1, 0. 5 and 1. 0 mass %) containing various amount of carbon (0. 001 to 0. 18 mass %). The fracture surface was examined to measure the degree of segregation of phosphorus and carbon. Phosphorus increases the ductile-brittle transition temperature both in intergranular and transgranular fracture mode, carbon tends to suppress the intergranular fracture. The optimum carbon concentration to improve toughness is 0. 01%.