Use of hypereutectoid high-speed steel 11M5F for the production of cutting and cold-stamping tools in the Avtovaz Joint-Stock Company

Abstract

The development of low-alloy high-speed steels that reduce the production cost of cutting tools and dies can present practical interest for plants and small enterprises manufacturing tools for their special purposes. The present paper gives the results of an investigation of hypereutectoid low-alloy high-speed steel 11M5F and a widely used steel of grade R6M5. The basic and technological properties of these steels are compared, and the results of industrial tests of cutting, thread-rolling, cold-stamping tools and tools for semihot deformation operating under various conditions are described.Volzhskii Automobile Plant (AvtoVAZ) devotes a great deal of attention to the study of new high-speed steels, including low-alloyed ones, with the aim of introducing them into the production process. Specifically, we studied native and imported powder high-speed steels R6M5F3-MP, R6M5K5-MP, R12M3F2K8-MP, KHA-30 (Cobe-Steel, Japan). After comparative tests steel R6M5F3-MP has been introduced into the production of large-size cutting tools at the Dneprospetsstal' Plant instead of R6M5K5.When studying the properties of low-alloy tungsten-free steels I~P973, I~KS0, I~K41, and I~K42 we established that their basic characteristics (heat resistance, secondary hardness in the treatment for a grain size of at most No. 10) and the technological properties (grindability, stability of the properties after the heat treatment) are greatly inferior to those of standard R6M5 steel. This conclusion has been confirmed convincingly by the results of production tests of cutting pieces, namely, the endurance of tools of steels i~K41 and EK42 did not exceed 0.12 -0.9 of the endurance of tools of standard R6M5 steel.However, the financial situation at machine-building plants requires measures for reducing the production expenses, including the use of low-alloy high-speed steels.The authors of [I] have conducted comparative tests of the basic properties of the most widely used low-alloy steels and established that the main operational characteristics of steel R6M5 correspond to those of steels IlR3AM3F2, R2M5, and 11M5F.However, it should be noted that steel 11R3AM3F2 has a worse grindability and adaptability to manufacture than steel AvtoVAZ Joint-Stock Company, Volzhskii, Russia.R6M5. For example, in milling of steel IlR3AM3F2 the tools wear 25-30% more intensely than in milling steel R6M5, the efficiency of the operation being decreased by 25% [3].The evaluation of the concentration of the main carbideforming elements in the solid solution and the insoluble carbides and of the amount of carbides in the considered steels (Table 1 [ 4]) has shown that the concentration of W, Mo, and V in the solid solution of steels llR3AM3F2 and I~K41 (I~K42) after quenching is much lower and the amount of carbides just lower than in quenched steel R6M5.Consequently, steels llR3AM3F2 and I~K41 (I~K42) theoretically cannot possess basic properties at the level of steel R6M5, which proves the results of independent studies