Study on the Quenching Structure of a Plain Carbon Steel (5th Report) : On Formative Condition of Low Carbon Martensite

It was generally believed that the mechanical properties of carbon steel were remarkably changed by heat treatment. But, generally speaking, in the case that the carbon content was below 0.2% it was difficult to expect the effect of heat treatment. In this paper, the present investigators, therefore, made a study of the effect of the quenching temperature and coolant on formatitive condition of low carbon martensite in the mild steel with carbon 0.07% preceded by normalizing at appropriate temperature through means of hardness, impact and metallography test. A summary of the results is shown below : (1) Except for spindle oil, in order to produce the maximum quench hardening effect it is necessary to quench after keeping 10 minutes about 900℃, and it is unconcerned in coolant. (2) 10% NaCl solution is best for coolant. (3) Factors affected on Charpy's impact value on the quenched mild steel are not hardness but its structure and austenite grain size.

Depth Perception

Multiple Cues

Cue Integration

Adaptation

Strong Fusion Model