i ve some experiment with AISI304 Plate by Cold WorkingRolli

i ve some experiment with AISI304 Plate by Cold Working(Rolling reducing in thickness from 8mm to 4mm,50% reduction). We have some data about hardness, HRB before=83,and after Rolling=111.8HRB...is it correct?
another question are :
- it turn from non magnetic to strong-magnetic, why was it?
- does it transform the phase from Austenitic to Martensite?how come?
- then we continuing the speciments (after Rolling)with Heating it in 2 temperatures condition :
@400 degree C
@800 degree C
what would be happen to its characteristitcs from those 2 speciments heated?
*we also do metallography on each speciments
thankyou

regards
atkin

Solution

1-The hardness values were found to increase with cold rolling. The cause of the change in hardness with cold rolling reduction may be attributed to the effect of the increased dis-location density, and the formation of strain-induced martensiteintroduced by cold deformation.So the given data is correct!

2-The main elements of austenitic stainless steel are nickel, chromium, manganese which divided to 200 and 300 series; the materials are non-magnetic normally but after cold processing will become magnetic. 304 could be general use and have great corrosion resistance, processing and welding properties.