- With the development of the automobile, machinery and other industries, higher and higher requirements are put forward for the materials used in the manufacture of various types of fasteners. The most effective measure is the high strength of bolt steel, and with the increasingly facing energy crisis. Non-tempered steel, which saves energy, reduces consumption, and simplifies the production process, will be used more and more. At present, the steel for high-strength U-bolts used for fixed leaf springs on trucks is mostly conventional quenched and tempered steel, such as 40Cr, 35CrMo, 45Mn2 and other medium carbon steels, which need to undergo spheroidizing annealing, pickling phosphating, cold drawing , rolling, forming, quenching and tempering, dehydrogenation annealing and other processes, energy consumption, long production cycle.
Scholars from Yunnan University studied the effects of cold-drawn surface reduction rate and aging treatment on the microstructure and mechanical properties of a bainitic cold-worked non-tempered steel. The steel was used to prototype 10.9 U-bolts. The results show that the strength of the material increases significantly with the increase of the cold drawing rate. When the cold drawing reduction rate is 26%, the tensile strength reaches the maximum value of 1134 MPa, which is due to the reduction rate of 26. At %, the strain hardening index n value peaks. After aging treatment at 100-500 °C, the strength of the steel increases first and then decreases. After aging treatment at 300 °C, the tensile strength and yield strength peak respectively, due to the change of precipitation behavior of carbide at different aging temperatures. The change in strength, the 300 ° C aging carbide precipitation size is small and the density is high, so the strength is high. The optimal process is formulated from the research results, and the performance of the trial-made bolts meets the requirements of the 10.9-class U-bolt of the truck, which can realize industrial production.
Wire Thread Insert is a new type of Inside screw fastener, generally it made of the cold rolled stainless steel wire which is with high strength, high precision and precise smooth surface. it is an Internal and external thread concentric body with high precision. When The wire screw suit is ready, it can form an internal thread with high precision and also can meet the corresponding standards. Its performance is superior to the internal thread which is formed directly by the tap.
Wire Thread Insert
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