Full Description
This paper which deals partly with interesting or novel applications of high-strength, low-alloy steels in the automotive field and partly with the superior mechanical properties and corrosion resistance of such steels has been presented in part before but it has not been published. Some of it was given before the Annual Convention of the Truck Body and Equipment Association. A great deal of the material which was available to me on the subject of high-strength steels dealt with operating costs of motor vehicles under a wide variety of uses. It is of course easy to understand why reduced license fees, reduced tire wear and reduced gasoline consumption are of prime importance especially to fleet operators but it seemed to me that many of the fundamental aspects of materials engineering had been either overlooked or ignored in favor of this type of cost study. Therefore, I decided not to talk about costs, at least in that fashion, but to concentrate on the engineering characteristics of the steel as I see them.These are the characteristics of the various metals which should be of prime importance to the automotive and allied industries because they are faced with placing on their products a trademark, which, in America, carries all the prestige and sales value of the hallmarks of earlier days. A product made of high-strength, low-alloy steel can carry your house name proudly. That should be of importance to the purchaser, too.The term high-strength, low-alloy steel embraces a group of 15 or more different, chemical compositions as made by nearly as many steel producers. Because all of those steels are proprietary, attempts to standardize on one or two chemical compositions have been largely unsuccessful. Moreover, in some cases the chemical composition of successful high-strength steel has arisen out of conditions surrounding the wholly owned or leased raw material sources of a single plant or company. To meet such chemical composition limits might work a hardship on other plants. Then, too, if the chemical limits of a standard were made sufficiently wide to cover the product of the majority of producers, the consumer would have little assurance that the steel would perform consistently in fabrication and use.But the fact that there exists a group of steels which do vary substantially one from the other in chemical composition yet consistently meet a standard set of mechanical property values, and which can be fabricated by standard methods by means of standard tools, gives the consumer a latitude in selecting steel which is, I think, unprecedented.Many of these steels are completely interchangeable with one another, or with the balance of the group. Some possess certain virtues in greater or lesser degree than others, yet all are outstanding in the field for which they were created-weight reduction.High-strength, low-alloy steels are available in any section which is available in plain carbon steel but, of course, all sections are not produced by any one company. In addition to the standard steel mill sections which are available, there is also available a nailable floor section and all types of Yoder mill sections. It is of decided economic and technical advantage to make use of the very wide variety of rolled special shapes which the steel industry makes available.During 1953 the automotive industry consumed 323,452 tons of high-strength, low-alloy steel or about 43% of the total production in the following major categories: structural shapes, 2342 tons; plates, 18,950 tons; bars and bar-size shapes, 802 tons; sheets-hot rolled, 213,569 tons; sheets-cold rolled, 74,736 tons; strip-hot rolled, 9282 tons and strip-cold rolled, 3771 tons. This represents an increase of 65% over 1952.In order to secure the superior mechanical properties which high-strength steels possess, manufacturers make use of combinations of several alloying elements and deliberately reduce the quantity of carbon present in the steel in order to enhance formability and weldability. In most cases the total alloy content, including manganese, will be around 2 to 3%.
View larger 