Composite Forging Extrusion Swing Process Achieved with Hydraulic Press

Literature Overview

This study examines the innovative application of hydraulic presses to achieve a combined forging-extrusion-swing process, a multi-step metal forming technique that integrates multiple deformation mechanisms into a single operational cycle. The literature describes how a conventional hydraulic press platform can be adapted to perform sequential and overlapping deformation modes, producing complex-shaped components with improved material flow and reduced defect incidence. The approach is particularly relevant to bimetal product manufacturing where precise control of interface bonding and cross-sectional geometry is critical.

Core Technical Principles

The composite process combines three fundamental deformation mechanisms within one hydraulic cycle:

Forging: Bulk plastic deformation under compressive loads to establish initial shape and refine grain structure.
Extrusion: Forward or backward material flow through a constrained die to achieve high reduction ratios and elongated grain orientation.
Swing: Rotational deformation applied to the workpiece during or after primary forming to homogenize microstructure and eliminate directional defects.

The hydraulic press provides the necessary tonnage (typically 1000–8000 tonnes depending on component size) while the tooling design ensures that each deformation phase transitions smoothly into the next. The key innovation lies in the die geometry and ram programming that allows the swing action to be superimposed on the forging-extrusion sequence without requiring separate equipment.

Process Parameters and Optimization

Parameter	Typical Range	Effect on Quality
Preheating temperature	1050–1200°C (for carbon steel)	Controls flow stress and recrystallization behavior
Forging reduction ratio	30–60%	Determines initial densification and grain refinement
Extrusion ratio	2:1 to 8:1	Influences fiber orientation and surface finish
Swing angle	90°–360°	Affects microstructural homogeneity
Ram speed (forging phase)	5–20 mm/s	Controls strain rate and adiabatic heating
Ram speed (extrusion phase)	10–50 mm/s	Influences die life and surface quality
Swing speed	0.5–3 rad/s	Must be coordinated with material flow rate
Die temperature	200–400°C	Reduces friction and prevents cold cracking

The optimization study demonstrates that the transition between forging and extrusion phases must be carefully timed to avoid stress concentration at the interface between deformed and undeformed regions. A dwell time of 2–5 seconds between phases allows stress relaxation and prevents crack initiation.

Integration with Bimetal Product Manufacturing

For bimetallic components, this composite process offers significant advantages over conventional methods. When applied to clad plate products or bimetallic bars, the combined deformation refines the interface between the base and overlay materials, reducing the risk of interface delamination under subsequent thermal cycling. The swing component is particularly beneficial for eliminating the "fish-tail" pattern that commonly appears in extruded bimetallic products, where differential flow between the two materials creates localized stress concentrations.

In practice, the process has been applied to produce:

Bimetallic shafts with stainless steel overlay for chemical processing
Nickel-alloy lined wear parts for mining equipment
Composite structural sections for pressure vessel components requiring localized corrosion resistance

Common Defects and Countermeasures

Defect Type	Root Cause	Countermeasure
Interface cracking	Differential thermal expansion during cooling	Implement controlled cooling rate below 50°C/min
Surface folding	Excessive swing speed relative to extrusion rate	Reduce swing speed to 0.5–1.5 rad/s
Grain coarsening	Overheating during prolonged dwell	Limit total cycle time to under 120 seconds
Non-uniform overlay thickness	Asymmetric die wear	Implement die rotation between cycles
Residual stress concentration	Rapid quenching after forming	Apply post-forming stress relief at 600–650°C for 2 hours

Study Insights and Engineering Implications

The literature demonstrates that the composite forging-extrusion-swing process represents a paradigm shift from sequential single-operation forming to integrated multi-deformation manufacturing. The hydraulic press serves as a versatile platform that, with appropriate tooling and control programming, can replace multiple specialized machines. This consolidation reduces capital expenditure, floor space requirements, and handling operations between stages.

From a quality assurance perspective, the process requires rigorous FMEA (Failure Mode and Effects Analysis) at the process design stage. The interaction between deformation modes creates failure modes that are not present in individual operations. For example, the combination of high strain rate during extrusion followed by rotational deformation during swing can create shear bands that act as crack initiation sites if the strain path is not properly managed.

The approach also has implications for weld overlay pressure vessel fabrication. Components pre-formed using this composite process exhibit more uniform grain orientation and reduced residual stress, which translates to improved weldability and reduced risk of hydrogen-induced cracking during subsequent overlay welding operations. This connection between forming and welding process design is an area where cross-disciplinary thinking can yield significant quality improvements.

The process parameters identified in the literature provide a solid starting point for engineering trials, but each specific application requires tailored optimization based on material combination, component geometry, and service requirements. The key takeaway is that multi-deformation processes, when properly engineered, can produce components with superior metallurgical quality compared to traditional single-operation methods, particularly for bimetallic applications where interface integrity is paramount.