KVA STAINLESS™ processing can be used to produce martensitic stainless steel seam-welded tubes with consistent properties throughout, replacing costly high-performance specialty alloy tubing while maintaining performance and reducing both production and material costs.
Continuous production of longitudinally seam-welded tubing has proven to be the lowest cost, most consistent method of making structural pipe and tube out of any alloy material. High production speed, excellent dimensional control, and wide availability of finished sizes make continuous roll-formed seam-welded tubing very attractive.
Unfortunately, many materials, including martensitic stainless steel are not compatible with the high-speed welding and forming that continuous roll-formed tubing entails. In these cases, tube drawing and hot extrusion processes have been used to successfully produce seamless pipe and tube. These batch methods require many intermediate thermal processing treatments - which are inherently slow and very costly - and have limited the widespread economical use of martensitic stainless steel high strength tubular shapes.
Additionally, other high strength steels and advanced alloys cannot be made into seam-welded tubing without a significant loss of strength in the weld and heat-affected zone (HAZ). The end result is a non-uniform product, which may be prone to failure or splitting in the weld or HAZ either during forming or in service.
KVA STAINLESS™ martensitic stainless steel seam-welded tubing offers stable pricing as martensitic alloys are not subjected to the volatile pricing spikes due to material surcharges and can benefit any market segment where component weight, strength and corrosion resistance are critical issues; providing a superior alternative to conventional alloys. KVA STAINLESS™ seam-welded tubing can replace seamless martensitic stainless steel tubes, expensive austenitic stainless steel tubing, exotic titanium alloy tubing, or specialty ultra high strength steel tubes, welded or seamless. Additionally, fully martensitic alloys can be used to produce KVA STAINLESS™ seam-welded tubing; in contrast to current methods utilizing reduced carbon - and reduced strength - modified weldable martensitic grades.
KVA STAINLESS™ processed MSS tubing exhibits a more uniform weld metal macrostructure than conventionally processed seam-welded tubing with less chromium carbide dispersion and segregation. Additionally, after a simple air-quench and temper heat treatment, which can easily be implemented in-line to the tube production process, a uniform, homogenous microstructure is obtained in the weld, HAZ and base metal - functionally equivalent to costly seamless tubing.
Similar to low-alloy steels, maximum strength and hardness of seam-welded martensitic stainless steel tubing primarily depends on carbon content. Low carbon martensitic stainless steel grades, such as AISI type 410, have tensile strengths in excess of 200 ksi (1400 MPa) in the fully hardened condition. Tensile strengths in excess of 300 ksi (2100 MPa) are possible in the higher alloyed martensitic stainless steel grades of KVA STAINLESS™ seam-welded tubing.
Recognizing the need for low-cost, high strength structural tubing, KVA STAINLESS™ founder, Mr. Ed McCrink, and development staff has implemented their patented welding and thermal processing technology to enable seam-welded martensitic stainless steel tubing. These technologies are the result of decades of metallurgical and thermal processing R&D and know-how. KVA STAINLESS™ proprietary, simple to implement methods have overcome conventional difficulties, without resorting to lower-carbon, lower strength alloys and enables the production of ductile, tough and reliable low-cost martensitic stainless steel seam-welded tubing.