Research And Development Of A New Kind Free-cutting Stainless Steel For Ball Pen Point

At present,our country has become the world's production and export country in pens manufacture,but it is not powerful.The yield of the ball-point pen that are middle and low grade are the greatest in various types of pens of our country,and most of the high ball-point pen that have a large gap with foreign ball-point pen,the key factor is the quality of ball-poin,that is the ball point structure,processing quality.The structure of ball-point pen is complex,and the machining are carried out in fully automated production lines,and production processes are numerous,and cutting speed is fast,and the accuracy of assembly and processing is high,therefore,it must have properties that are high free-cutting,broken chip,high surface finish and less tool wear for the ball-point pen material.At present,it mainly use free-cutting stainless steel for high-grade ball-point pen material,which is research and producted very little in domestic and mainly depend on imports,and therefore it is urgent and necessary to research and develop free-cutting stainless steel for ball-point pen.This article,in view of this situation,a new type of S-Pb free-cutting ferritic stainless steel for ball-point pen by researched and developed by Nanjing Jinlianan metallurgial and electromechanical Ltd and us through studying the domestic and foreign test results and combined with knowledge of the principles.In this paper,the intermediate frequency furnace and ESR smelting,hot maching, and cold maching technology of a new type of free-cutting stainless steel for ball-point pen were sumarized detailedly.a variety of test and analysis means were used to research the smelting and maching technics,and reveal the influence of the steel performance(cutting performance,chip morphology,surface coarseness grade,etc.) to different inclusions charicteristic(type,morphology,size,amout and distributing),and illustrate the relation between steel smelting,processing technology,inclusion morphology,and performance,and thereby the optimized maching technology were put forward.The test showed that the free-cutting phase of tested steel are mainly MnS,Pb,and Te phase.MnS inclusions in hot rolled bar are small and oval,and distribute uniformly. After hot machining the horizontal MnS inclusion of the free-cutting stainless steel are oval,and vertical MnS inclusion have a discontinuous distributin along with rolling direction of the steels by the form of chains.Pb,Te and its mixture phase are small granules and disturibute in steel matrix or on both sides of MnS.The Cr and Mo carbide phase in the steel is brittle,and coexist with MnS,they are broken and have a discontinuous distributin along with rolling direction of the steels by the form of chains, which is important to improve inclusion morphology and the strength of steel matrix. The cutting performance of the S-Pb free-cutting stainless steel better than the S free-cutting stainless steel and SUS 304 stainless steel,and the bigger cutting dosage can be choosed and producticity are advanced.The microstructure of the tested steel wire rod are smaller and more evenly distributed and more than the SF20T steel wire rod which is imported,and their performance are dosed,and they have good microstructure and free-cutting performance,and their performance can be meet the requiement of production and use,and achieve the level of foreign steels.The tested steel is a special free-cutting steel,which is used for ball-point pen,and instrument,the part have a high corrosion resistance and nonmagnetic,and high maching precision and high maching performance,etc.So it have a good market prospect to research and develop the free-cutting stainless steel for ball-point pen.