Solid State Diffusion Bonding of Superplastic Duplex Stainless Steel with Carbon Steel

Abstract

Solid state bonding between superplastic duplex stainless steel with carbon steel under low pressures is studied for the objectives to understand bonding behaviors and to determine mechanisms controlling bonding through the activation energy analysis. Experiments were carried out by combining several bonding parameters such as bonding temperatures, bonding pressures and surface roughness. Bond quality was evaluated by its tensile strength. Bonding strength increased with temperature, time and pressure but decreased with surface roughness. Sound bonds comparable to that of the parent metal were obtained at considerably short bonding time and low and 220 s bonding time, producing the parent metal strength with around 1% of deformation ratio. Changes in microstructures and hardness were observed across the bonding interface, due to diffusion of atoms, mainly C, from the carbon steel side to the duplex stainless steel side. A hard carburized layer formed at the DSS side and a soft decarburized layer at the carbon steel side. From the value of activation energy and experimental data, bonding was controlled mainly by two mechanisms, which were the superplastic deformation at the early stage and the diffusion of carbon at the second stage.

Effect of Powder Particle Sizes on the Development of Ultra Hard Surface Through Superplastic Boronizing of Duplex Stainless Steel

“…To the authors' knowledge, this is the highest hardness value obtained through boronizing of ferrous alloys. As explained in the previous work (9) , through superplastic deformation of the DSS substrate's surface asperities, diffusion of boron atoms into the surface can be accelerated. The initial pressure applied not only superplastically deformed the surface asperities of substrate but also compacting the boron powder so that less void or space exists between them.…”

“…The solution treated DSS was then cold-rolled to a plate through a reduction area of 75%. Figure 2 shows fine microstructure of the thermo-mechanically treated DSS after reheated at boronizing temperature of 1223 K. Under this temperature condition, superplastic elongation of 1050% has been achieved (9) . Specimens were cut from the thermo-mechanically treated plate to a dimension of 10 X 10 X 8 mm.…”

Comprehensive Study of the Deformation Behavior during Diffusion Bonding of 1.4301 (AISI 304) as a Function of Material Width and Aspect Ratio

“…Diffusion bonds of high-alloy austenitic steels are possible in a wide range of process parameters. Different authors report temperatures ranging from 850 to 1100 • C, contact pressures of 2 to 15 MPa and dwell times on temperature not exceeding 60 min [16][17][18]. However, for microstructured devices made from several layers, the experience of the authors showed that longer dwell times led to improved bonding results.…”

Boronization and Carburization of Superplastic Stainless Steel and Titanium-Based Alloys

“…Diffusion taking place on interface is important to consider the strength of SPF-DB. An example, in which diffusion affects the fracture strength of bonded materials by SPF-DB, is mentioned in this section [ 8 , 9 ].…”