The temperature control springs made of nickel-titanium alloys are widely used in the temperature control valve core. At lower temperature，Martensite phases occurs in the nickel-titanium alloy springs，and the Martensite phases will change into Austenite with the temperature going up. The recovery force, which can be used for driving, is engendered. We annually provide approximately 300,000 pieces of nickel-titanium alloy springs to the purchaser. The phase transformation temperature and recovery stress of nickel-titanium alloy springs is according to the requirement of purchaser.