How does the workpiece obtain a microfluidic structure with excellent performance?
Annealing will make the steel soft, and the quenching will make the steel hard. In contrast, if the "normalization" treatment is applied, the layered wave iron structure can be obtained, which can effectively improve the machinability and wear resistance of the steel. Sex, at the same time, it has the advantages of no cracks, less deformation and convenient operation. However, normalization is a difficult heat treatment technique because it is cooled by air cooling, which is affected by many factors, such as different cooling effects in summer and winter, different workpiece sizes, air cooling rates, and even wind blowing. It also affects the cooling rate. Therefore, the normalization process uses various methods to maintain uniformity, and can use sunshades, curtains, potholes, fans, and the like.
Difference between normalization and annealing
Normalization treatment is heated to A3 point or above Acm point 40~60 °C for a period of time, so that the steel structure becomes a uniform Worth field structure, and then cooled to room temperature in a static heat treatment program. For the hypoeutectoid steel, the grain refinement can be obtained with good strength and toughness; for the hypereutectoid steel, the ferritic carbon iron can be prevented from forming a network precipitate on the iron grain boundary of the Worthfield. To reduce the toughness of the material.
The main purpose of the complete annealing treatment is to soften the steel and improve the machinability of the steel. The heat treatment procedure is to heat up to 20~30 °C (sub-eutectoid steel) above A3 point or 30~50 °C above A1 point for a period of time to form After the complete Worth field structure (or the Worth field plus the snowy carbon body structure), the wave body is fully deformed at 50 ° C below the A1 point, and the softened steel is obtained. In addition, the stress relief annealing is cooled to room temperature after heating for a period of time from 450 to 650 ° C below the transformation point, which can eliminate the residual stress generated in the steel during cutting, stamping, casting and welding.
How to eliminate the residual stress of the workpiece?
The stress relief annealing is to cool to room temperature after heating for a period of time from 450 to 650 ° C below the transformation point, which can eliminate the residual stress generated in the cutting, stamping, casting and welding process of the steel. For carbon steel, the reference heating temperature is 625 ± 25 ° C; for alloy steel, the reference heating temperature is 700 ± 25 ° C. The holding time will also vary. For carbon steel, the holding time is 1 hour for every 25mm thickness. For alloy steel, the holding time is 2 hours for every 25mm thickness, and the cooling rate is 25mm every time. Cooled at a cooling rate of 275 ° C / hour or less.
How to prevent heating deformation?
To prevent the occurrence of heating deformation, it is preferable to heat slowly and carry out preheat treatment. Generally, when selecting the preheating temperature, the preheating temperature can be selected according to the following criteria: (1) The preheating temperature is below the metamorphic point, for example, the ordinary steel is about 650~700 °C, and the high speed steel is 800~850. °C or so. (2) The preheating temperature is about 500 °C. (3) Two-stage preheating, first preheating at about 500 °C, and after preheating for a period of time, the preheating temperature is raised to below the A1 metamorphic point. (4) Three-stage preheating
