Quantification of Compositional and Residual Stress Efects on Lattice Strain in Dual-phase Stainless Steels by Means of Diferential Aperture X-ray Micro-difraction

Residual stress is an important factor for evaluating the deformation and failure of engineering materials. Diffraction-based measurement assumes that the full measured lattice strain tensor contributes to residual stress according to Hookers Law. The present work focuses on the lattice strain determination of individual grains in a dual-phase stainless steel （DPSS） by means of differential-aperture X-ray micro-diffraction （DAXM）. The results show that the residual stress only takes part of the responsibility of the total measured lattice strain. In fact, the compositional variation inside the material was found to cause greater strain gradient in both ferrite （c~） and austenite （~） phases in DPSS. Therefore, quantification of compositional and residual stress effects on lattice strain was conducted in order to evaluate the true residual stress inside engineering materials.

Effect of hot rolling and cooling process on microstructure and properties of 2205/Q235 clad plate

The 2205/Q235 clad plate was fabricated by vacuum hot rolling with symmetrical assembling pattern of Q235/2205/2205/ Q235.The flow stress behavior and processing map of 2205 duplex stainless steel (DSS)were investigated by hot compressive tests on a Gleeble-3800 simulator.Then,thermal-mechanical coupled nonlinear finite element models of vacuum hot rolling and subsequent cooling process were established.From the simulation results,the influence of rolling reduction and rolling speed on hot deformation state of 2205 DSS in the assembled slab was disclosed and the optimal rolling parameters were presented.Meanwhile,the cooling rate of 2205 DSS under different cooling conditions and thicknesses of the clad plate was obtained.According to the numerical simulation results,pilot experiments were successfully carried out on a laboratory scale.The material universal testing machine,optical microscope,scanning electron microscope and energy-dispersive spectrometer were used to evaluate the mechanical properties and microstructure of bonding interface and 2205 DSS matrix for different rolling reduction and cooling processes.The results showed that with symmetrical assembling pattern,the approximate thermodynamic conditions can be established for 2205 DSS to avoid cracks in hot rolling process.When the rolling reduction increased from 10 to 40%,the shear strength of the bonding interface is increased from 120 to 530 MPa,and the uniform two-phase microstructure of 2205 DSS and satisfactory' mechanical properties can be obtained with cooling rate higher than 10℃/s between 1050 and 500℃ after rolling.