Effect of initial exposure temperature on the deuterium retention and surface blistering in tungsten

•Exposure temperature in the initial stage strongly affects the subsequent deuterium behavior in tungsten.•Initial exposure at 420 K significantly inhibits the formation of intergranular blisters and leads to a reduction in the size of intragranular blisters.•Initial exposure at a relatively high temperature of 600 K leads to a reduction in the size of intergranular blisters and reduces deuterium retention by ∼ 34 %.•The gradient distribution of deuterium over a larger depth leads to the intergranular cracks more prone to propagate along sloping grain boundaries.