A forging method for preventing cracks in hot forging of mn18cr18n steel retaining ring

Abstract

The invention relates to a forging method for preventing cracks from being generated by the hot forging of a Mn18Cr18N steel protecting ring, which belongs to the technical field of the hot-forging formation of alloy steel. Used devices comprise a boss, a bottom die, a cylinder die, a punching head and a leaking disk. The forging method for preventing the cracks from being generated by the hot forging of the Mn18Cr18N steel protecting ring is characterized in that the forging method comprises the following steps: (1) placing the boss in a conical hole of the bottom die and placing the boss and the bottom die at the inner bottom of the cylinder die together; (2) sleeving a wrapping sleeve outside a blank tightly and heating the wrapping sleeve and the blank to 950 to 1200 DEG C together; (3) placing the blank and the wrapping sleeve which are heated in the cylinder die, and carrying out impact extrusion on the blank from the top by using the punching head so as to reach the designed depth, wherein the difference delta of the outer diameter of the wrapping sleeve and the inner diameter of the cylinder die is equal to 0.03D to 0.10D; (4) removing the boss and replacing by the leakingdisk; (5) stamping the blank continuously by using the punching head, and stamping off burrs at the bottom of the blank; and (6) quitting the punching head and taking out an annular forged piece so as to finish the operations of punching and forming. The forging method for preventing the cracks from being generated by the hot forging of the Mn18Cr18N steel protecting ring has the following advantages that: (1) a clearance is remained between the wrapping sleeve and the cylinder die, so that the cracks generated at the surface of the forged piece can be prevented, and the tonnage of required equipment can also be decreased; and (2) crystal grains inside the forged piece can be thinned.

Description

technical field [0001] The invention belongs to the technical field of alloy steel hot forging, and in particular relates to a forging method for preventing cracks from hot forging of Mn18Cr18N steel retaining rings. Background technique [0002] The retaining ring is one of the large key parts of thermal power equipment. It not only bears huge centrifugal force during high-speed rotation, but also bears thermal loading stress, alternating stress, and bending stress. It requires sufficient strength, good toughness, Uniform mechanical properties, minimum residual stress, and the guard ring works in a strong magnetic field and a corrosive atmosphere. Therefore, it is also required to be non-magnetic and have high stress corrosion resistance. At present, the method of forging retaining ring parts at home and abroad generally adopts the process of heating and forging a ring blank from a steel ingot, and then making a forging through a process of solid solution treatment and cold...

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Problems solved by technology

For example, ZL200510012565.2 "A Method and Die for Making Hot Forging Ring Blank of Generator Guard Ring" has many outstanding advantages compared with the fre

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