THE STRUCTURES AND PROPERTIES OF ROLLED 0.18-PERCENT PLAIN CARBON-STEEL STRIP PRODUCED BY LIQUID DYNAMIC COMPACTION

Liquid dynamic compaction (LDC), a spray deposition process which yields as-deposited sprayed densities of 96+/-3% against a water cooled mild steel substrate, was applied to the production of low (0.18 wt.%) carbon, plain carbon steel sheet and strip. Resultant as-deposited materials showed fully crystallized, fine grained (10 to 40 mum, on average) structures. Cooling rates during solidification were about 10(3) K/s and solid state cooling rates were 10(1) to 10(2) K/s depending on spray forming variables. The as-spray-deposited plates were warm rolled to full density at 700-degrees-C (873 K) in the ferrite plus carbide region and hot rolled at 1050-degrees-C (1323 K) in the austenitic state. Less than a 70 per cent reduction was required to achieve full density in 2 to 3 passes. The resultant grain sizes of 1 to 10 mum were a function of the total reduction, with emphasis on the reduction in the final pass. A variety of simple heat treatments were utilized, resulting in increases of 25 to 50 per cent in yield and ultimate tensile strength values at high levels of ductility as compared to properties of the same grade of steel produced by ingot technology, continuous cast thick slabs, and plates spray deposited against preheated substrates.