Improved mild steel for structural purposes

Abstract

THE majority of structures is usually constructed from steels with yield points not more than 17 t.s.i. but the recent developments in this field have led to structural steels with yield points between 20 t.s.i. and 40 t.s.i. Additions of about 2% allo- ying elements can produce appreciably higher yield strength. These low alloy steels show good impact properties and render them suitable for use at temp-eratures down to -50°C or even lower.The improvement in yield, tensile and impact properties are not achi- eved at the expense of weldability because carbon, the principal cause of welding trouble, is maintain- ed at a very low level. The type of steels to be dis-cussed has a low carbon I'5 Mn base with very small quantity of alloying elements, and it would not be improper to term them as improved mild steel. By making use of strengthening mechanisms in mild steel containing residual alloying addition, it would be possible to use a cheaper steel in structures needing a more highly alloyed steel, and a significant reduction in cost can be achieved. Also, by replacing mild steel with this improved variety, thinner sections can be used in structures and this would increase the payload of vehicle and a consequent reduction in freight cost.