Research On The Basic Chemical Components And Alloying Treatment Of Machine Tool Bed Casting With High Strength And Low Stress

It becomes an important means of gaining high strength,high elastic modulus,low stress lathe bed to improve machining precision of lathe and maintain stable accuracy based on the inherent structural characteristics of lathe bed and requirements of the high performance of the guideway.This paper is to control carbon equivalent,Si/C and Mn/S synthetic parameters and to finish low alloying or micro alloying processing,thus the stable bulk production of high carbon equivalent,high silicon carbon ratio,high elastic modulus,low stress HT300 high-end CNC machine with low-cost will be realized under the condition of production,with high-end CNC machine tools as the object,on the premise of improving carbon equivalent,through reasonable equipping of the four elements of C,Si,Mn,S.It is illustrated through the statistical analysis of a large number of production data that the increase of silicon carbon ratio plays a very weak role in the ascension of the action of the elastic modulus for HT300,high carbon equivalent(CE is greater than 3.8).When silicon carbon ratio is more than 0.6,the action of the elastic modulus will be reduced with the increase of silicon/carbon ratio,and the effect which silicon carbon ratio lays on the promotion of strength and hardness is obvious.In order to achieve better mechanical properties,silicon/carbon ratio should remain at around 0.6.Modulus of elasticity,strength and hardness of gray cast iron are reduced with the increase of manganese/sulfur ratio in 7?15.A low alloying processing with an add of 0.5%copper or the micro alloying treatment through SiBaSb inoculation has obvious improvement on the mechanical property of HT300.HT300 is mainly composed of graphite A and pearlite.The content of graphite A is 85%?95%and the content of pearlite is 95%?98%.The austenite dendrite quantity is between 20%?30%.If its graphite quantity is less and the form is small and curly with high degree of dispersion of pearlite layer and a number of austenite dendrite,it is more advantageous to have higher mechanical properties of castings.The stress of the optimized casting with high carbon equivalent and decreases significantly.It can be fallen by 42%When the carbon equivalent increased from 3.64 to 3.77.To give full play to the potential of the material performance,the first thing is to deal with the proportion of the four elements:the carbon,silicon,manganese and sulfur,making the silicon/carbon ratio in the range of 0.57?0.63,the manganese sulfide range in 9?13 for high carbon equivalent(CE = 3.75%?3.75%).The high-end CNC machine tool lathe bed casting and high strength gray cast iron with high carbon equivalent material can be achieved by adding 0.4%?0.6%Cu in low alloying,or by adding 0.015%?0.025%Sb in micro alloying processing.