Hot tear defects a horror for steel foundries-with case studies supported by AutoCAST CAD simulations
This study presents an in-house experience of the dangerous effect of hot tear in steel castings and its practical remedies. This is also a detailed guideline of step by step analysis of hot tear defects and some tactful solution of this problem supported by AutoCAST simulation software. This paper is based on industrial case studies of export items (American Bogie Castings) and covers all possible causes generating hot tear and highlights some practical approaches to get rid of this defect and improve quality and save cost as this defect causes a lot of rejections or rework before use under stress conditions. In steel castings contraction takes place during solidification and hot tears are initiated at a temperature within the solidification range of the alloys, that is some time before the solidus temperature is reached. Further opening and extension of tear can however occur at lower temperature due to continuing lower contractions. Generally two conditions are necessary for hot tearing: (a) There must be resistance to contractions; (b) There must be variable temperature gradients within the casting section. The low collapsibility of cores/mould materials, higher percentage of sulphur and phosphorous, excessive large feeders used causing obstructions during contractions, faulty design of castings i.e. wide variations in wall thicknesses, too high pouring temperatures etc. causing hot tears in steel castings are discussed here along with remedial measures.
hot tears solidus and liquidus temperatures solidification range chromite sands tie rods anti cracker ribs/ cooling brackets alpha set / ester cured core making system simulations
Tapan Roy
Steel Foundry Division, TEXMACO LTD., Belgharia, Kolkata - 700056, India
国际会议
The 11th Asian Foundry Congress(第11届亚洲铸造会议 AFC-11)
广州
英文
1-6
2011-11-12（万方平台首次上网日期，不代表论文的发表时间）