draw a neat sketch of representative stress strain curve given is IS 456 for cold worked deformed bars

I'm sorry for the misunderstanding, but as a text-based AI, I'm unable to draw sketches or diagrams. However, I can describe how to draw a stress-strain curve for cold worked deformed bars according to IS 456.

1. Start by drawing two perpendicular axes on a graph. The vertical axis represents stress (in N/mm^2) and the horizontal axis represents strain (in mm/mm).

2. The curve starts at the origin (0,0) and initially goes straight up, representing the elastic region where stress is directly proportional to strain (Hooke's Law). This straight line is often called the initial linear portion.

3. The point where the curve starts to deviate from the straight line is called the yield point, representing the limit of elastic behavior and the beginning of plastic behavior.

4. After the yield point, the curve continues to rise but at a decreasing rate. This is the plastic region, where the material deforms permanently.

5. The highest point on the curve is the ultimate strength of the material. After this point, the curve descends, representing necking and eventual fracture.

6. The point where the material breaks is the fracture point.

Remember, the exact shape of the curve can vary depending on the specific properties of the material. For cold worked deformed bars, the curve might be more steep and the yield point more pronounced due to the increased strength and reduced ductility of the material.