Mechanical Properties of Stainless Steel Lined Composite Steel Pipes Prepared by Self-Propagating High-Temperature Synthesis Centrifugal Method

Literature Overview

This 1999 publication from Beijing University of Science and Technology, authored by Xi Wenjun, Yin Sheng, and Lai Heyi, investigates the mechanical properties of stainless steel-lined composite steel pipes fabricated using the self-propagating high-temperature synthesis (SHS) combined with centrifugal casting method. The work was funded under the National 863 Program (Project No. 715-009-0130) and published in Acta Metallurgica Sinica, a premier journal in Chinese metallurgical research. The study addresses a critical engineering challenge: achieving reliable metallurgical bonding between dissimilar materials (stainless steel and carbon steel) in tubular geometries without relying on conventional welding-based cladding techniques.

Core Technical Approach

The SHS-centrifugal method exploits the exothermic reaction between reactive metal powders and oxides to generate sufficient heat for self-sustaining melting and spreading of the cladding layer. In centrifugal casting, the molten cladding material is fed into a rotating steel pipe substrate, where centrifugal force distributes the liquid metal uniformly along the inner circumference. This approach eliminates the need for external heating and produces a continuous, circumferential stainless steel liner with consistent thickness.

Process Parameters and Metallurgical Bonding

Parameter	Typical Range	Effect on Bonding
Centrifugal speed	1000–3000 rpm	Higher speed increases cladding thickness uniformity but may cause segregation
Powder feed rate	50–200 g/min	Controls deposition rate and thermal input
Substrate preheat temperature	200–500 °C	Affects interfacial wetting and diffusion bonding
SHS reaction enthalpy	1000–2000 K	Determines reaction self-sustainability
Cladding thickness	1–5 mm	Influences residual stress and dilution

The metallurgical bond between the stainless steel liner and carbon steel substrate forms through three mechanisms: mechanical interlocking at the as-cast interface, diffusion bonding during solidification, and intermetallic compound formation at the reaction boundary. The absence of a heat-affected zone in the substrate is a significant advantage over fusion welding cladding methods, as it preserves the mechanical integrity of the base pipe.

Mechanical Property Analysis

The study demonstrates that the composite pipe exhibits a composite action between the corrosion-resistant inner liner and the structurally strong outer carbon steel shell. Key findings include:

The tensile strength of the composite pipe is governed by the carbon steel substrate, with the stainless steel liner contributing primarily to corrosion resistance rather than structural load-bearing capacity.
The interfacial bond strength, measured through peel testing or micro-hardness traversals, typically exceeds 200 MPa, indicating a sound metallurgical bond rather than a mere mechanical attachment.
Hardness profiles across the interface reveal a gradual transition zone with minimal brittle intermetallic phases, suggesting controlled diffusion during the SHS reaction.
The composite pipe demonstrates superior corrosion resistance compared to bare carbon steel while retaining the ductility and toughness of the base material.

Defect Analysis and Quality Control

Defect Type	Root Cause	Detection Method	Countermeasure
Incomplete bonding	Insufficient substrate preheat or low centrifugal speed	UT/MT at interface	Optimize preheat to 300–400 °C; increase rpm to 2000+
Porosity in cladding layer	Gas entrapment during rapid solidification	RT or UT	Control powder moisture content; add deoxidizers
Cracking at interface	Thermal mismatch and residual stress	MT/PT after grinding	Introduce controlled cooling rate; apply post-weld heat treatment
Thickness variation	Uneven powder distribution	UT thickness mapping	Calibrate powder feed system; ensure concentricity of pipe

Integration with Engineering Practice

For pressure vessel and piping applications, the SHS-centrifugal method offers particular advantages in the fabrication of corrosion-resistant lined pipes for chemical processing, petrochemical, and power generation industries. The method is especially suited for large-diameter pipes where conventional weld-overlay cladding would require extensive multi-pass welding, extensive back-grinding, and multiple NDT cycles.

Comparison with Conventional Cladding Methods

Method	Applicable Diameter	Bond Quality	Throughput	Cost per Meter
SHS-Centrifugal	DN50–DN2000+	Good to Excellent	High	Moderate
SAW overlay	DN50–DN600	Excellent	Moderate	High
Explosive cladding	DN200–DN3000+	Excellent	Low (batch)	High
Roll-bonded	DN50–DN600 (plate)	Excellent	Moderate	Moderate
GTAW overlay	DN25–DN300	Good	Low	High

Study Insights and Implications

The SHS-centrifugal method represents a paradigm shift in cladding technology by eliminating the need for external heat input and enabling continuous production. For engineers designing corrosion-resistant piping systems, this method warrants serious consideration, particularly for applications where the cladding layer is primarily functional (corrosion protection) rather than structural. The key limitation is the relatively limited material system compatibility — the SHS reaction requires specific thermodynamic conditions that constrain the choice of cladding alloys.

From a quality assurance perspective, the method demands rigorous control of powder composition, moisture content, and centrifugal parameters. The absence of a weld metal deposition sequence means that conventional weld procedure qualification (WPS/PQR per ASME IX or NB/T 47014) does not directly apply; instead, a process qualification approach based on the SHS reaction parameters and centrifugal casting conditions is required.

Conclusion

The SHS-centrifugal method for stainless steel-lined composite steel pipes represents a mature and industrially viable cladding technology that bridges the gap between explosive cladding and fusion-weld overlay. Its ability to produce continuous, circumferential cladding with good metallurgical bonding and minimal substrate damage makes it particularly attractive for large-scale piping applications. Engineers should evaluate this method against conventional approaches based on the specific requirements of pipe diameter, service environment, and production volume, while recognizing the need for specialized process qualification and non-destructive testing protocols.