抄録
The cause, reality and preventive method of surface flows of Ni-Cr-Mo high strength steel of rolled bars of 18mm dia. were studied. Summary of the experiment is as follows:-
1) The most remarkable of the surface cracks are traced back to the local failure of the material due to the concentrated over-stress during rolling.
2) Most of the failure of rollings occur at inside of the parts bent and compressed inward by missqueezing or with the next calibre.
3) Reality of the most remarkable surface flows is the remains of the broken and oxidized parts of the material.
4) Peeling-off of the blooms has not the final and definite effect as the method of preventing the flows of the product.
5) Lowering of the rolling temperature scarcely affects the occurrence of flows.
6) The preventive method of the remarkable flows in the steel concerned should be pointed to exclude any chance of local bending inside during the pass through calibres. Prevention of even the slight mis-squeezing should be most noted.
7) Moreover, the experimental data of some effects of the occurrence and elimination of surface flows were also described.
