"square corners" is a perfectly correct and usable phrase in written English.
For example, you could use it in a sentence like this: "The edges of the painting frame had been sanded down, leaving the wood with smooth, square corners."
Square borders, square corners.
High compressive stress concentrations are found to exist at the four square corners.
Early cartes pre-18700) tond to have square corners, as here.
His grave was dug precisely, by hand, and a mourner admired its craftsmanship and square corners.
Early cartes tend to have square corners, as here, and display little or no advertising.
The rounded corners suggest a date before 1900, when square corners again became popular.
Mr. Kalmár essentially stripped Artists Space and left it almost bare, revealing as never before the beautiful bones of the big square corner loft in SoHo that has been its home since 1993.
A second, square corner living space adjoins the first, which in turn connects to the kitchen with a complete wall of windows looking out onto the twin building across the street.
Mr. Snow has yet to attain master status with the British walling association, which would require him to build a perfectly round pillar as well as an exquisitely square corner, among other features, as part of his examination.
As part of the effort to simplify our visual style, the design team recently decided to go back to our square corner roots.
As this passage indicates, the Mohists regard fa (models) as similar to tools used to guide and check the performance of skilled tasks, such as sawing a square corner or drawing a straight line.
