Will IronOCR read captcha codes?

This is possible, but not guaranteed.

Most CAPTCHA generators are deliberately designed to fool OCR software and some even use "Failing to be read by OCR Software" such as Tesseract as a unit test.

Captcha code are by definition very difficult for OCR engines to read. The resolution is very low and each character is specifically organized with different angles and gaps from the others, along with the inclusion of variable background noise.

Grayscale images with background noise removed are more successful than color images, but can still prove a challenge: