There is no impeachment process for members of Congress. However, the members themselves can vote to expel a member. The only 5 members ever expelled are all DemocRats. Three of them were Confederates, so that doesn’t really count.
A Senator was impeached by the House in 1797, but the Senate didn't want to have the House impeaching Senators, so the Senate expelled him instead, setting a precedent for future Congresses.
The Founders wanted representatives to have some freedom from changing public opinion, so they didn't support any recall procedure.