I suspect that most American lawyers and law students regard express warranty as neither more nor less than a term in a contract, a term that is subject to conventional contract rules on formation, interpretation, and remedy. Assume, for example, that a buyer sends a purchase order to a seller and the purchase order specifies the delivery of 300 tons of "prime Thomas cold rolled steel." The acknowledgment also describes the goods to be sold as "prime Thomas cold rolled steel." Every American lawyer would agree that there is a contract to deliver such steel and furthermore would conclude that the seller makes an express warranty that the steel delivered would conform to that description and that the seller would be liable for breach of its contract if it failed to deliver steel that conformed to that description. So we would say that the description is an express warranty and that the express warranty is neither more nor less than a term in a contract.
White, James J. "Freeing the Tortious Soul of Express Warranty Law." Tul. L. Rev. 72, no. 6 (1998): 2089-111.