In most engineering designs, fracture toughness, a property describing how cracked objects resist fractures, is a chief property in most applications. Stress intensity factor (K), examines the linear-elastic fracture toughness of the sample under observation when its crack begins to grow. KIc denotes the fracture toughness, with SI units of Pa or ksi. Plastic-elastic fracture toughness is the energy the crack requires to grow. JIc is a symbol that denotes energy and has units of J/cm2 or lbf-in/in2. Ic denotes that the crack is opening normally, that is, it is opening at the right angle of the tensile stress as the sample crack deeply grows to withstand both shear and tear forces.
Understudy is two samples A and B, analysis of the toughness factor and the energy required to grow cracks in this sample will give a quantitative expression of the sample’s resistance to fragile fracture in the presence of a crack. Samples with high fracture toughness undergo ductile fracture while those with small fracture toughness undergo brittle fractures. Analysis of how thickness affects the toughness of these samples. The original crack length of A is 10.165mm while that of B is 10.511mm. The a0/W ratio is 0.523 for A and 0.541 for B. The results do not meet the validity criteria.
The results show that the thickness affects the fracture toughness with temperature has no significant effect on the material fracture toughness, as it undergoes heat treatment before the experiment. Determination of the tensile factor may fail because of the design of the sample’s material. This causes the crack length to vary from one notch to the other. The thicker sample has a lower fracture toughness than the thinner sample. The sample fracture shows significant plastic deformation along the plastic zone. Yielding occurs near the boundary of the plastic zone at the surface.
Sample A has a fracture under plastic conditions thus does not give a valid toughness factor. Sample B, which is thicker than sample A gives a valid toughness structure of 115.18Mpa. This shows that the thicker the sample the more valid the toughness factor is than that of sample B. This condition varies with temperature; at higher temperatures, the thickness of the sample would have extremely little effect on the fracture toughness. A constant temperature gives a reliable comparison of this factor for samples. Strain fracture toughness happens to cracks that are close to the linear force and displacement behavior. Plastic-elastic has higher values of toughness. There is an assumption of any pop-ins giving less than 1% displacement. The other significant pop-ins calculate K1c and CTOD values, as they give more information in the experimental analysis of sample A and sample B.
Analysis of samples A, B, and calculations of Crack Tip Opening Displacement values (CTOD) show that the samples had different values depending on their thickness. There are more visible large cracks growth in sample A and a smaller one in B. The crack length is about half of the full extension in each case.
The Crack Tip Opening Displacement was under investigation for both sample A and sample B. Sample A gives higher values, in the analysis than that of A. The appropriateness of this was a measure of the effect of thickness of the fracture toughness of the sample. Sample A and sample B’s effects on fracture toughness depend on their thickness and the stress applied to them. At higher values of thickness, the fracture toughness is at a constant level but lower than that of thinner materials. The energy requirements to grow the crack, which is the J-integral, is higher in sample A than in B, this shows that the thicker the sample the lesser the energy required for cracks growth. The test’s temperature was constant at 25ºC and had little effect on the experiment.
Pop-ins are more significant in the thinner samples than in the thicker samples. In a thinner sample, deformation occurs earlier before the plateau of the deformation curve causing pop-ins to be less than 5%, which is less significant. They are crucial when calculating the J-integral; thus, a higher J-integral is present in thinner samples than thicker samples. There is an observation of a linear relation between load line displacements (q) between line (W–a0) that supports the concept of a constant Crack Tip Opening Displacement during “steady-state crack” propagation. If a comparison, between the strain and stress curves for the two samples, thicker sample handles comparatively lower values of strain and stress than the thinner one, thus leaving a conclusion that thinner sample A handles twice as much fracture toughness than sample B.
In conclusion, the lack of a valid K1C value shows that fractures in this experiment occurred under elastic-plastic conditions. It is also clear that the thickness of a “475ºC Embrittled” Duplex Stainless Steel has a high effect on the fracture toughness. An observation throughout the analysis reveals that thickness has a significant impact on the fracture toughness at room temperatures such as room temperature. Thicker materials have lower fracture toughness than thinner materials, thus sample A has higher fracture toughness than that B. Therefore, thickness affects the fracture toughness of “475ºC Embrittled” Duplex Stainless Steel.