Effect Of Modification On The Microstructure And Properties Of Lead-free Casting Brass

In this paper, lead-free silicon brass, bismuth brass and tin brass as the research object, through the organization of test methods, performance testing, heat treatment, corrosion and scissel chip test, study the boron refining agent, composite refining agent and industrial refining agent on the micro structure and properties of the experimental materials, the conclusion is:the B refinement processing, when the boron content is0.002%, the silicon brass lead-free organization best refinement effect; with the increase of boron content, the tensile strength and hardness lead-free silicon brass was increased and then decreased, the elongation decreased to different extent, section shrinkage rate increased in different degree; when the boron content of anti the strongest corrosion0.008%silicon brass, corrosion depth minimum, about175μm. When the boron content is0.004%, the best lead-free organization bismuth brass refinement effect; different boron addition thinned, tensile strength, hardness and bismuth brass elongation and contraction rate increased at different degree, boron addition is0.004%, Bi brass has better comprehensive properties when the boron content is0.01%; at best, anti dezincification corrosion resistance, corrosion depth is only about315μm.Lead free silicon brass and bismuth brass respectively by No.6and No.4, the composite refining agent treatment, the best refinement effect, the best performance, anti dezincification corrosion is the best. For detailed treatment with boron and compound refining agent, can significantly improve the cutting performance of lead-free silicon brass and bismuth brass.Boron refining lead-free silicon brass at400～500℃, β phase size smaller; with the increase of heat treatment temperature, the tensile strength of the material is increased and then decreased, and hardness, elongation and contraction of small range, comprehensive mechanical properties of lead free silicon brass heat treatment at500℃is better, more than400℃with heat treatment improves the corrosion depth temperature significantly smaller. Leadless bismuth brass boron refining, after heat treatment at400℃organization is relatively small,500℃-600℃β phase obviously increased after heat treatment. After heat treatment at400℃, material and has high and dezincification corrosion properties of the best mechanical properties.After composite refining process, the size of lead-free silicon brass on β phase is smaller by heating at600℃; with the increase of temperature, the tensile strength decreased first and then increased, elongation increases first and then decreases, the corrosion layer depth decreases. Leadless bismuth brass after heat treatment at400℃, the organization is relatively small; with the increase of temperature, the tensile strength of the material increases, the corrosion layer depth increased firstly and then decreased.Industrial Refining on lead free silicon lead-free bismuth brass have certain refinement refinement effect, the mechanical properties are improved significantly, but the industrial refining agent on these two kinds of material restraining zinc corrosion has little effect. Industrial refiner added0.02%to lead free tin brass microstructure refinement was. Industrial refiner of different addition amount on lead free tin brass strength, hardness and elongation are considerably improved. Industrial refiner added0.02%,0.2%, the corrosion resistance of lead free tin brass has increased significantly, and the corrosion depth respectively:256.5μm,268.5um.