Hochschild, Kohn & Co., the 84-year-old Baltimore department store, last week took a big step into the Baltimore-Washington "common market" by opening its first Washington-area store.

The new store, Hochschild's 10th, is located in Bowie's Free State Mall on Annapolis Road. It will carry only ready-to-wear clothing and accessories for men, women and children. Most Hochschild's are full-service department stores.

"We believed for our type of store," said Leroy Danielczyk, senior vice president for finance and operations for the firm. "The Bowie-Crofton area is one where we feel we can meet the needs of the customer.

"We are expansion-minded, but we're no longer adding the huge stores."

The new Bowie location has about 20,000 square feet of retail space, compared to Hochschild's old 160,000-square-foot Columbia store, which in 1976 was sold to the Hecht Co. Danielczyk said Hochschild's would consider returning to Columbia "if the opportunity presented itself."

Hochschild executives have completed negotiation of a lease for another Hochschild's in the Carrolltown Mall in Carroll County. Danielczyk said occupancy of that store is scheduled for about March 1982.

Other sites under consideration by Hochschild, Kohn, according to Danielczyk, include Salisbury and Cambridge in Maryland and out-of-state locations in the Delaware Valley.

Hochschild, Kohn, which closed its former flagship store in downtown Baltimore in the late 1970s, is owned by Supermarket General Corp., of Woodbridge, N.J.