Super Mold Steels V3N

After screening assessment on the production performance, process performance is also better steels welcomed by mold manufacture and use of units of the mold service life even more than the level of similar mold at home and abroad, such as Beijing University of Iron and Steel Technology Daye steel mills in the development of the Co superhard high speed steel W12Cr4Mo3V3N (V3N) the performance is excellent, the People’s Republic of China by the National Invention Award, the patent of the People’s Republic of China (91102252), V3N mold performance than the current ordinary high-speed steel increased by 2 to 10 times, equivalent to the international market with high speed steel, containing 10% Co has successfully promote the use of the tool and die production, can increase exponentially life.

V3N Composition and Performance Characteristics

W12Cr4Mo3V3N (referred to V3N) is tungsten - molybdenum nitrogen-containing cobalt super-hard high-speed steel, of V3N of chemical composition c: 1.21%; W: 11.88%; Mo: 2.95%; Cr4.00%; V: 2.87%; : 0.075% novel superhard high speed steel v3n component design features are:

High C: C cold work die steel strength and toughness, wear resistance have a decisive impact. The carbon content is increased, the increase in compressive strength and wear resistance. Therefore, impact resistance and high tensile cold work die steel, high carbon content.

High V: V strong grain refinement, strongly improve the wear resistance and red hardness and secondary hardening ability. Too much obvious deterioration the malleability and grinding.

Containing N: N grain refinement, but also precipitation strengthening, and the mechanical properties and weldability are good.

The main technical performance: v3n steel with high hardness, good wear resistance, high red hardness and toughness, cold work die steel effect is very significant. The steel and cobalt high speed steel, inexpensive and easy to process, can be obtained by appropriate heat treatment, high hardness (HRC67 to 70), high red hardness (625 ° C for 4 hours, HRC63 to 65) and high wear resistance, toughness and flexural strength of not less than ordinary high-speed steel, mold edge collapse and crack early damage can be overcome.

V3N Steel Mold Process

Mold heat treatment methods and processes choose the same mold working conditions, failure mode and the performance of the different requirements. You should continue to improve the heat treatment equipment, improved heat treatment process, so that the strength of the material, the toughness of the best fit, and strictly follow the heat treatment process, control the heating temperature, time, cooling rate, in order to ensure the performance of the mold.

1. Forging. V3n steel contains a lot of carbides and secondary carbides, if retained in quenching organization, will dramatically reduce the life of the mold. Only through change the forging of raw materials, crushed carbide, for it was a small, uniform morphology is distributed in the steel matrix, to improve the overall mechanical properties.

V3n steel poor thermal conductivity, forging billet heating should be fully preheated, initial forging temperature of 1170 ° C, the final forging temperature of 950 ° C, the device can be used 250kg (small pieces) and 400kg air hammer, light hammer Fighter, in the middle with a heavy hammer fight, the last flick slow play, forging asbestos powder box after removing the slow cooling after annealing.

2. Forging Annealing. Isothermal annealing can be used or 860oC annealing 4 hours. High hardness after forging, isothermal or annealing, machining can be carried out smoothly, work high hardness after quenching the workpiece forming grinding more difficult, can be used praseodymium niobium corundum and chromium produced by the grinding wheel.

V3N steel at 1220 ° C to 1230 ° C quenching, due to the presence of unmelted carbides, low hardness of the Department of the quenching temperature; when quenching at 1260 ° C to 1270 ° C, significant grain is too large, overheating. Select 1230 to 1240 ° C quenching temperature both carbides and alloying elements fully dissolved into the austenite, whilst maintaining a smaller grain size (10 to 10).

V3N super-hard high speed steel die parts 1220 to 1230 ° C after tempering at 550 ° C four times, the hardness can be controlled in HRC64 ~ 67 specific size according to the size of the part to be adjusted from the heat treatment process to achieve an ideal hardness and strength with V3N super-hard high-speed steel after quenching more residual austenite, it was determined about 25% to 30%, must be minimized to reduce, for a number of high-temperature tempering of martensite transformation. 4 high-temperature tempering, most of the retained austenite to martensite, resulting in secondary hardening effect. V3N steel secondary hardening effect of temperature 30 ~ 40 ° C higher than the average high-speed steel, this feature is very valuable, indicating that higher red hardness v3n steel.

By cryogenic treatment, the retained austenite to martensite and fine carbide precipitation, hardness and wear resistance of the mold parts will further improve the wear resistance can be increased by 40% and shorten the tempering time to save energy , but also significantly improves the mold life.

The cryogenic treatment process of high-speed steel mold: mold into a holding tank except oil → a few times into the liquid nitrogen (196 ° C) → insulation soaked 2.5h → remove the mold quickly placed in a 60 ° C to 70 ° C hot water.

V3n Steel Application and Effect of Cold-Working Die

V3N superhard cold work die life than the Cr12MoV, Cr12 common mold life expectancy increased by 3 to 5 times higher than the current ordinary high-speed steel, 2 to 10 times, more significant economic benefits, v3n steel mold performance equivalent to the international market now 10% Co-containing high-speed steel.

The factory silicon steel die original CrWMn, Cr12MoV chrome steel production, but hard surface such as silicon steel brittle, so the mold large amount of wear and tear, V3N steel production mold, the economic effect.