Residual Stresses in Green Bodies of Steel Powder and Their Relaxation during Heat Treatment
2000 (English)In: 20th ASM Heat Teating Society Conference,2000, ASM International, 2000, 435-440 p.Conference paper (Refereed)
Stresses and residual stresses have been measured in rectangular bars after compaction under 400 and 530 MPa after the removal of the pressure and in three positions: The bar completely inside the die, the bar partially outside and the bar completely free. The stresses have been measured by X-ray and neutron diffraction. It was found that stresses around 35 MPa in compression on the top surface prevail when the bar is inside the die and it is reduced to half when the bar is partly outside and even more when completely outside the die. However on the side surfaces considerable compressive residual stresses exist in the free bar in a thin surface layer and tensile residual stresses below this layer. It is proposed that plastic deformation of the side surface during ejection is a major cause for the residual stresses. Heat treatment at 450°C decreases the residual stresses. Two different powders have been used: Höganäs ASC 100.29 with lubricant added and Höganäs Distaloy AE without lubricant. The presence of lubricant reduces the residual stresses. Direct current potential drop, DCPD, measurements have also been carried out and are discussed together with the residual stress data.
Place, publisher, year, edition, pages
ASM International, 2000. 435-440 p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-30164Local ID: 15650OAI: oai:DiVA.org:liu-30164DiVA: diva2:250985
20th ASM Heat Teating Society Conference, 9-12 October 2000, St. Louis, Missouri, USA