Experimental Study On Mechanical Properties Of Stainless Steelwires For Bridges

The composite system bridges such as cable-stayed bridges and suspension bridges are widely used in recent years,and the corrosion problems of stainless steel wires for bridges have always been a hard technical problem today. Suspension cables play an important part in bridge structure because it is the main load-bearing part for bridge. However,as the corrosive suspension cables always working under the high stress state,coupled with the long-term effects of environment and load,which makes the corrosion and fracture of suspension cables has always been the major safety risk in bridge construction.At present,it is difficult for traditional protection technologies to solve the corrosion problems of steel wires(steel strands)fundamentally,and the method that using stainless steel wires for suspension cables instead of steel wires(steel strands)is more accepted. The method can solve the corrosion problems of steel wires(steel strands)fundamentally,which helps the bridge construction development healthy a lot in long term.As the main material of suspension cables for bridge,the stainless steel wire should work with the characteristics of not only stainless and corrosion resistant property,but also excellent mechanical property. Therefore, this thesis carried out experimental studies on mechanical properties of stainless steel wires:(1)Make a scientific summary on influence factors of mechanical properties of stainless steel wire,including the chemical composition of materials,mold material and lubrication condition,drawing speed and temperature,drawing passes and area reducing rate,pre-tension,the time and temperature of thermal treatment,annealing time.(2)Do tensile tests at room temperature on stainless steel wires of different drawing passes,area reducing rates and the temperatures of thermal treatment. Through the tests,the yield strength,tensile strength,elastic modulus,elongation after fracture of stainless steel wires were educed and preliminary compared,arrival at the conclusion that the tensile strength and the yield strength increasing while the area reducing rate decreasing, and the thermal treatment can improve the comprehensive properties of stainless steel wires.(3)By analyzing the influencing factors to results of tensile test at room temperature on stainless steel wires,arrival at the conclusion that the tensile strength and elastic modulus of samples increasing with the increasing of tensile testing speed, but the speed of tensile test has unclear influence on the area reducing rate decreasing of stainless steel wires.(4)Do fatigue performance test on stainless steel wires and produce the result that most of samples have a fatigue test number more than 4 million,but there are still some samples cannot meet the national regulatory requirements(2 million),which indicating that the quality stabilities of samples still need to be improved.(5)Do relaxation test on stainless steel wires and produce the result that the 1000 h relaxation rate of sample calculated by computer is basically the same as the linear regression,which can reflect the relaxation properties of stainless steel wires.