1.Design a dual phase contains 50 wt% of ferrite and 50 wt% martensite. The martensite should contain 0.6 wt% of C. Your answers should include: the steel's composition, the temperature for heat treatment and how to heat treated steel to get the required structure.

2. The fatigue crack growth rate of a high strength steel with a plane strain fracture toughness of 80 MPa/m obeys the Power law: da/dN=1.62x10^-12(deltaK)^3.2. a is the crack length. N is the loading cycle number and deltaK is the stress intensity factor range. Once each five minutes, the steel was loaded in tension t0 500 MPa and in compression to -60 MPa. Suppose the dimensionless parameter for the stress intensity calculation is Y=1 and the compressive stress is not inducing crack propagation. Find the maximum allowable initial crack length if the plate is expected to survive 10 years.