Abstract
(i) When we introduce the idea of sliding resistance and resistance to rupture and use the hypothese of the greatest shearing stress as in the 1st report, we can apply. Woodvine's theory for the bending properties in the (two surface) case of hardened steel. But in this case we must take care of the case break point, which often appears after some plastic d eformation.
(ii) Case hardened steel is not especially rich in velocity sensibility for its charpy value is almost equal to the energy of rupture by statical bending test.
(iii) The case hardened layer on the surface of the greatest bending load is most resistant for sliding.
(iv) In the specimens of (_??_=Const), the impact value per unit area of the high height specimens are superior to those of low height.
(v) We can apply the two layer theory by Woodvine in the all surface case hardened steels.
(vi) In the notched specimen, there is a stress concentration around the notch part. Thus, the case depth which brings on the rupture of separation type moves to the shallow depth.
(vii) This tendency to the rupture of separation type moves to the bigger notch in the lower temperature.
(viii) With the increase of impact velocity, the notch sensitivity does not increase in the case of hardened steel.
(ix) In the high height specimen with the standard notch, its impact energy (E/bh2) is abosrbed much more than that of the lower height specimen.
