Effect of Cold Working on the Mechanical Properties of a Medium Carbon Low Alloy Steel

Missile and rocket motor cases are often fabricated by welding process. The replacement of welded hardware with the flow formed construction eliminates many problems associated with welded joints. Data on the cold workability of the material in different heat treatment conditions is essential for the flow forming of the material. The cold workability of a 0.3C-CrMoV grain refined steel processed by air melting and electroslag refining was studied in annealed and Q&T conditions through cold rolling process. The effect of heat treatment on the strength properties of the rolled materials was also studied. The observed behaviour is explained in the light of the results of the microstructural characterization.

Examination of the Mechanical Properties of Steel S460 for Fire

To establish a basis for calculating the load-bearing capacity of steel members made of S460 in a fire, corresponding to EN 1993-1-2, the mechanical properties of the micro-alloyed grain refined steel S460 under high temperatures have been examined. Two different types of steel have been considered: a normalized rolled S460 N and a thermo-mechanically rolled S460 M, that differ in their chemical composition and the temperature control during the hot-rolling process. On the basis of transient warm-creep tests, constitutive laws have been derived for the temperature range 20-900°C. The testresults show an increased strength of S460 M at elevated temperatures in comparison to S460 N. This is a result of the strain hardening caused by the thermo-mechanical rolling and the reduction of the creep-velocity caused by niobium- and titanium-precipitations. The data derived from the tests show that the stress-strain curves given in EN 1993-1-2 for S460 overestimate both the strength and the stiffness of the examined S460 N.