high strength levels have been developed for air-
 craft landing gear. The stainless steels .
 provide good corrosion resistance and are
 useful in applications requiring strength at
 elevated temperatures .

 Today's steel line pipe, because of greater
 strength and larger diameter, enables use of
 greater pressure to transmit 60 percent more gas
 than was possible a decade ago with the same
 tonnage of pipe. The new A-36 grade of structural
 carbon steel has a yield point 9 percent greater
 than that of the A-7 grade which was the standard
 for many years. This higher yield point allows
 an increased design stress of about 10 percent in
 both bridges and buildings and will result in
 significant savings in the cost of fabricated and
 erected structures.(43)

 The effects of improved quality have been twofold.

First, because proportionately more special steels are

being used today, and because these are higher cost

steels, more value is added per ton of metal in the

production of steel itself. Second, the increased

quality of steel of all grades has decreased the amount

of steel needed per unit of final product and also has

increased the durability of the product so produced.

Increased durability has allowed machines to be operated

longer and at higher speeds, thus increasing the amount

of product produced per machine and per unit of metal

used in the machine's construction.

 The trend toward increased value of production

per ton of metal also has been accentuated by the

changing nature of metals markets, and this influence


 4American Iron and Steel Institute, The
Competitive Challenge to Steel, p. 14.