The phrase "a steep grade" is correct and usable in written English.
It can be used to describe a slope or incline that is significantly steep, often in the context of roads, hills, or terrain.
Example: "The hikers struggled to ascend the mountain due to the steep grade of the trail."
Alternatives: "a steep slope" or "a sharp incline."
They were looking for a steep grade to test one of their new models.
A steep grade that also traverses a flowing creek bed leads to a fork in the road.
I forget about it even going up a steep grade with concrete construction barriers, which I normally dread for fear the car will ricochet.
As Mr. Rittner led us up a steep grade, he explained that all this sand was deposited at the end of the Ice Age.
Yet the A8L managed to feel a bit sluggish when merging into traffic at 45 m.p.h. or climbing a steep grade in high elevations.
They reduced a steep grade by adding six switchbacks, each anchored with a massive keystone that they found, unearthed and replanted.
As the hill dropped off at a steeper grade, her still-moving feet lifted away from the grassy slope.
I always marvel at the way the stretch of Interstate 5 called the Grapevine winds its way down a very steep grade for six miles before it dumps you into Virtual Indiana.
While significantly longer than the more direct Ridge Route (modern Interstate 5), Tehachapi Pass is lower than Tejon Pass along the Ridge Route, with a longer, less steep grade on the descent into the Central Valley.
The long, steep grade offered an opportunity to move the shifter to "B" — for braking — putting the hybrid drive system into a mode that enhances the car's regenerative energy gathering, banking electrons in the nickel-metal-hydride battery for later use.
The course led into the mountains at a steep 12 percent grade, higher than the maximum incline on most treadmills.
