The Research Of Cast Steel Shot’s Ervin Life And Influencing Factors In Centrifugal

With the development of science and technology, and the increasing of people’s conscious for the environmental protection, a large number of steel that was dealt with the original acid are largely replaced by shot blast cleaning. In order to reduce the release of waste acid and waste water, the use of steel pill dosage increases further. At present, the cast steel shot is the most widely used metal abrasive for blast cleaning and shot penning, and it is applicable for blast cleaning and shot penning of the metallic surface in the fields,such as auto industry, ship building, rolling stock, aero craft, bridge, container, mechanical manufacturing and steel structure etc.This essay focuses on the research of the Ervin life of the cast steel shot and its-influenced factors. Firstly we studied the Ervin life tester by splitting and its principle is; Then we studied as-cast low chromium alloy cast steel shot by tempering heat treatment(450℃～650℃), and the heat treatment process were analyzed in low chromium alloy cast steel shot, the influence of microstructure, hardness, Ervin life search optimal temperature and holding time of tempering process; Ervin life tester is used to analyze the high carbon、low carbon、low chromium alloy cast steel shot and S260～S550five kinds of grain size of low chromium alloy cast steel shot; According to the analysis of the wear failure mechanism of low chromium alloy cast steel shot.The results are that:Ervin life tester by splitting and its principle is imitation of shot blasting machine design, through the impact to cast steel shot a high velocity impact hardness of target, realize the blast simulation, throwing device of rotational speed, shape, size, surface hardness, impact size and hardness of target material is the main parameter Ervin life testing machine, its value directly affects the size of the cast steel shot Ervin life.As-cast (a quenching) low chromium alloy cast steel shot microstructure for thick plate martensite retained austenite;When the as-cast low chromium alloy cast steel shot directly tempering process, the higher tempering temperature from450℃to650℃, gradually transforms the microstructure from the coarse martensite tempered troostite and tempered sorbite, tempered sorbite by axial ferrite and fine granular cementite; Cast steel shot the hardness of HRC from62.8to29.3HRC; Cast steel shot Ervin life gradually increases; Comprehensive analysis of the microstructure, hardness, Ervin life and actual production efficiency and cost into consideration, the best tempering temperature is600℃,20min insulation. From high to low three kinds of cast steel shot that are discovered in Ervin life were low chromium alloy cast steel balls, low carbon cast steel shot, high carbon cast steel shot. Ervin life results showed that within a certain range, with the increase of particle size, cast steel shot Ervin life gradually increased. We found that the main wear failure forms of cast steel pill by surface spilling, heart crack, three kinds of brittle fracture, and they are made up by three failure modes, not a single form of some kind of failure. Ervin life testing machine cycles and microstructure defects of cast steel shot itself affects the wear failure forms, surface spalling occurs in the whole failure process of cast steel shot, the heart of cracking occurs after the cycle, the more the better the quality of the cast steel shot. When the crack of cast steel pill or porosity is larger, the brittle fracture happended, and the heart crack will also resulted in brittle fracture.