Abstract: The Hydrogen-induced embrilttlement of cold supporting roll steel 70Cr3Mo was studied by means of slow tensile of specimen with various hydrogen contents. The results show: (1)with the increase of hydrogen contents in the steel and the retardation of strain rate, its plasticity drops sharply till almost wholly lost when hydrogen was 6ml/100g and strain rate was down to 3×10 -5s -1.(2)The hydrogen content of the steel to free flack or hydrogen-included embitterment is limited to 3.0 or 1.48ml/100g respectively .(3)The flack is slow tensile test specimen revealed similar elliptical freckles and sharp boundaries. The micro morphology is Tran granular quasi-cleavage consisting of clear leering ridges and tiny, winding quasi-cleavage pleases.

Key words: 白点, 缓慢拉伸, 冷轧辊钢