The author discusses the different types of material used in the production of the Liberty engine, the physical properties of the finished parts and the heat-treatments used in making them, applying the information as set forth to the automobile, truck and tractor industries. Under their several heads the different engine pans are discussed with close attention to details. Chemical analyses are given for each part and approved heat-treating temperatures are indicated. Quenching, direct and indirect, water and oil cooling, hard spots, warpage, scaling and hair-line seams are treated. The advantages and disadvantages of the Izod impact test are stated briefly.
After discussing the various engine parts, the author makes definite recommendations for the use in detail of the materials discussed, with many hints, warnings, suggestions and comments along lines of practice and closes the paper with a statement that if the proper authority be given to the metallurgical engineer as to the handling of the steel from the time it is purchased until it is assembled into finished products, mild-analysis steels can be used and quality guaranteed. It was only through careful adherence to the fundamental principles outlined that it was possible to produce 20,000 Liberty engines without a failure of a single engine from defective material or heat-treatment.