| Forging cannot only control the size and shape of product flexibly and conveniently, which possesses a small machining allowance, but also improve the cast structure of ingot so that the material becomes dense and toughness is increased, therefore technology is widely applied to various processing areas. Design of Si-Mn-Cr-Balloy steel is optimized on the basis of traditional Si2Mn3, at the same time a certain amount of alloying elements Cr, B, etc are added in order to obtain a low-alloy high-strength wear-resistant steel. Because it has excellent mechanical properties and low cost, so the material has also been widely used in various fields. Combining these two points, it is particularly important in the forging process through controlling the recrystallized structure of Si-Mn-Cr-Balloy steel with forging technology.However, in actual production our understanding is not clear for the thermal processing characteristics of new steel, and technology system of process is not perfect and defects are prone to produce such as surface cracks, internal cracks, so it affects the forging molding of products eriously. Generally these problems can be solved by thermal processing drawings, therefore it has great theoretical significance and practical value explore the Si-Mn-Cr-B-based alloy high-temperature plastic deformation characteristics with thermal processing drawings. On the Gleeble 1500D thermal/mechanical simulation testing machine, flow different deformation conditions curves and high temperature deformation microstructure were obtained under different deformation conditions(T:950-1200℃,ε:0.01-5s-1)by thermostatic constant strain rate compression test. According to the data obtained by compression tests, a flow stress model Si-Mn-Cr-B-based alloy and recrystallization model were established and forging process experiments were carried on at work shop. At the same time, it provides the theoretical basis for the optimization of process parameters, the principles of general process developing and the possible range of process parameters.Firstly, single-pass compression was carried on by thermal simulation compression test, and compression test data were obtained in order to study the flow stress behavior of material. Flow stress increases with the decrease of deformation temperature and the increase of strain rate, and its true stress-true strain curve shows a dynamic recovery and dynamic recrystallization. Parameters were obtained and flow stress constitutive equation, the percentage of dynamic recrystallization model and the theory of dynamic material model (DMM) were established, and thermal processing drawing with strain of 50%was constructed.Secondly, quantitative analysis was carried on to the material by metallurgical test, and average grain size of Si-Mn-Cr-B alloy was measured with different deformation conditions, and the average grain size was studied with different conditions. The results show that:the grain size decreases with the increase of strain rate; increases with the increase of temperature; with the increase of amount of compression, dynamic recrystallization is more obvious, grain size becomes smaller, and the grain becomes uniform. Meanwhile, dynamic recrystallization grain size model was created with the parameters of the material.Finally, original blank size Φ110×186 cylinders forging was forged on the air hammer by experimental research methods, and final forging was a ball of Φ150. Determining the optimum forging process by theoretical and experimental parameters:its initial forging temperature range is 1000～1050℃, final forging temperature range is 900～950℃, air hammer forging force is 750kg～1000kg, upsetting forging ratio is 1.2 to 1.5.
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