Abstract: A process for increasing surface hardness of a heat-hardenable steel disk, along an annular band intermediate the disk central and edge portions, is disclosed. The process contemplates selecting a first position on the surface of the intermediate annular band. The process contemplates next rapidly heating at the first position a minor portion of the disk surface in relation to the remainder of the disk so as to cause the minor portion to increase in temperature to an elevated temperature ranging from 1400 to 1600 degrees Fahrenheit in a time period of 0.3 to 0.7 seconds. The disk is heated in a manner such that substantially no heat diffuses from the thus-heated portion of the disk to the remainder thereof. The process next contemplates rapidly terminating the heating step to allow the remainder of the steel disk to serve as a heat sink to rapidly cool the thus-heated portion from the elevated temperature to less than 1000 degrees Fahrenheit in 0.

Abstract: A bolt for attaching an earth engaging plow component to a plow frog has an improved head configuration represented by planar surfaces having inclined angular displacement similar to the slope of the truncated cone portion of the plow bolt head.