Materials - 4340 Steel - Stress Corrosion and Effects of Banding - Literature Survey. Part II: Effects of Banding

摘要

Banding is caused by segregation of the alloying elements in ingots during solidification. During subsequent hot working operations the segregation is aligned in the direction of working and results in a banded appearance of the microstructure. The diffusion rates of the alloying elements in steel control the homogenization of the ingot, chromium and molybdenum homogenizing readily and nickel very slowly. The increase in properties by homogenizing does not warrant the involved process of homogenizing, then refining the resulting large grain size. The fact that design can orient the plane of maximum stress in a direction parallel to the working direction of the stock or forging, it is felt, has lead to the economic infeasibility of performing the very involved and costly task of homogenization. This behoves the designer to take as much advantage of controlling grain flow as possible. (Author)