Hardenability
15CrMo steel of Cr, Mo, C and other Brazing Alloy elements, the increase in carbon equivalent, so that the hardenability of the steel tendency is more obvious, weldability deteriorates. Under specific cooling rate in the weld thermal cycle, the weld and heat affected zone are likely to form a crack-sensitive tissue.
Reheat cracking
15CrMo heat resistant steel containing Cr, Mo, Mn and Si, and other carbide forming elements, and have a certain degree of superheat zone reheat cracking tendency. Prevention measures are:
(1) strictly control the content of the base metal and weld materials of Mn and Si alloying elements;
(2) selection of plastic Welding Material is higher than the base metal;
(3) an appropriate increase in the temperature between the preheat temperature and layer Road;
(4) using a small line of energy, limit the width of the overheated zone, inhibiting grain coarsening;
(5) try to shorten the the reheat cracking sensitive temperature interval holding time in the heat treatment process;
(6) the rational design of joint form to reduce the structure of the binding.
Temper brittleness
Harmful residual elements such as higher levels of P, S, and joints long the temperature range of 370 ~ 565 ℃ run, will lead to temper brittleness.