A: First of all, I am not sure S7 is the right choice for the impact tool you described. My suggestion is either S5 or H13. Both also have good impact properties, and the S5 does not have as much alloy content as the S7, which contains over 3.2 Cr and 1.4 Mo and 0.3 V. This grade (S7) is good for warm working or shearing. H13 is a stainless grade that has excellent impact properties and heat resistance, but its hardness capability is not as high as S5. If no heat is involved with the impact tool, then S5 should do just great.

For more than 40 years H. James Henning held key technical positions in the forging industry, including as director of technology for the Forging Industry Association, and as president of Henning Education Services, a Columbus, OH, firm specializing in customized education and training in forging technologies.

Guidelines and recommendations offered in this column are based on information believed to be reliable and are supplied in good faith but without guarantee. Operational conditions that exist in individual plants and facilities vary widely. Users of this information should adapt it, and always exercise independent discretion in establishing plant or facility operating practice.